Clasificación de leucemias - OMS 2008
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Clasificación de leucemias - OMS 2008 Clasificación de leucemias - OMS 2008 Presentation Transcript

  • World Health Organization Classification of Tumours Hamilton SR. Aartonen LA (Eds.): World Health Organization Classificationof Tumours, Pathology and Genetics of Tumours of the Digestive System (3rd edition) . IARC Press: lyon 2000 ISBN 92 832 2410 8 Fletcher C.D.. Unni KK., Mertens F. (Eds,): World Health Organization Classification 01 Tumours. Pathology and Genetics 01 Tumours of Soft Tissue and Bone (3rd edition). IARC Press : lyon 2002 ISBN 92 832 2413 2 Tavassoli F A.. Devilee P.(Eds.): World Health Organization Classification 01 Tumours. Pathology and Genetics of Tumours of the Breast and Female Genital Organs (3rd edition). IARC Press: lyon 2003 ISBN 92 832 2412 4 Eble J.N., Sauter G.• Epstein J E., Sesterreon l.A. (Eds.) World Health Organization Classification of Tumours. Pathology and Genetics of Tumours althe Urinary Systemand Male Genital Organs (Jrd ed ition) fARe Press : lyon 2004 ISBN 92 832 2415 9 Travis wo., Brambilla E., Muller· Hermelink H.K ., Harris C.C. (Eds.): World Health Organization Classification 01 Tumours. Pathology and Genetics of Tumours of lung P1eu"a. Thyrrus and Heart (3I"dedilon), IARC Press : lyon 2004 ISBN 92 832 2418 3 Delellis A.A., lloyd A.V, Heitz, P.U., Eng C. (Eds.): World Health Organization Classification of TlJTlOUrs. Pathology and Genetics ot TlJTlOUrs of Endocrine Organs(3rd edition). IARC Press: lyon 2004 ISBN 92 832 2416 7 Barnes L , Eveson J.W , Reichart P" Sidransky 0 (Eds.): World Health OrganizationClassification of Tumours. Pathology and Genetics of Head and Neck Tumours (3I"d edition) . IARC Press: lyon 2005 ISBN 92 832 24 17 5 leBoit P.E.. Burg G , Weedon D., Sarasm A. (Eds.): World Health Organization Classification of Tumours. Pathology and Genetics of Skin Tumou rs (3rd edition). IARC Press: lyon 2006 ISBN 92 832 2414 0 louis D.N" Ohgaki H., WiesUerD.O., Cavenee WK (Eds.): World Health Organization Classification of Tumours. Tumours of the Central Nervous System (4th edition ). IARC, lyon 2007 ISBN 92 832 2430 2 This book and all other volumes of the series can be purchased from: From all countries WHO PRESS World Health Organization 20 Avenue Appia 1211 Geneva 27 Switzerland www.who intlbookord ers/ Tei. +41 22 791 3264 Fax +41 22 791 4857 bcokoroersewno.ot From USA I Canada WHO Publications Center 5 Sand Creek Road Albany, NY 1205-1400 Tel. +15184369686 Fax. +1518436 7433 Renouf Publishing Co. lid http://www.renoufbooks.comJ From USA: Tel.+18885517470 From Canada: Tel. + 1 866 767 6766 Fax +18885517471 Fax +16137457660
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  • • I WHO OMS International Agency for Research on Cancer (IARC) 4th Edition WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues Edited by Steven H. Swerdlow Elias Campo Nancy Lee Harris Elaine S. Jaffe Stefano A. Pileri Harald Stein JOrgen Thiele James W. Vardiman International Agency for Research on Cancer Lyon, 2008
  • World Health Organization Classification of Tumours Series Editors Fred T. Bosman, M.D. Elaine S. Jaffe. M.D. Sunil R. Lakhani. M.D. Hiroko Onqaki, Ph.D. WHO Classification of Tumours of the Haematopoietic and Lymphoid Tissues Editors Sleven H. Swerdlow, M.D. Elias Campo. M.D. Nancy Lee Harris, M.D. Elaine S. Jaffe, M D. Stefano A. Pileri. M.D. Harald Stein, M.D. JOrgen Thiele, M.D. James W. Vardiman, M.D. Layout Sebastien Antoni Marlen Grassinger Pascale Collard Printed by Participe Present 69250 Neuville s/SaOne, France Publisher International Agency for Research on Cancer (IARC) 69008 Lyon. France
  • • This volume was produced with support from the Associazione S.P.E.S. Onlus, Bologna Friends of Jose Carreras International Leukemia Foundation Leukemia Clinical Research Foundation MEDIC Foundation National Cancer Institute, USA National Institutes of Health Office of Rare Diseases, USA University of Chicago Cancer Research Center The WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues presented in this book reflects the views of a Working Group that convened for an Editorial and Consensus Conference at the International Agency for Research on Cancer (fARC), Lyon October 25-27. 2007. Members of the Working Group are indicated in the List of Contributors on pages 369-374.
  • Published by the International Agenc y for Research 00 Cancer (IARC), 150 cours Albert Thomas, 69372 Lyon ceoex 08, France C International Agency for Research on Cancer, 2008 Distributed by WHO Press, World Health Organization , 20 Avenue Appia, 1211 Geneva 27, Switzerland (Tel: +41 22 791 3264; Fax: +41 22 791 4857; e-mail: bookordersOwholnt). PubliCations Of the World Health Organization enjoy copyright crotectco in accordance with the proviecos of Protocol 2 of the Universal Copyright Coeventoo. All rights reserved. The designatiOns employed and the presentation otthe material in this publicatiOn do not imply the expression ot any opiniOn whatsoever on the part of the secretarial 01 the WOOd Health OrganiZatiOn concerning the legal status 01 any country , territory. city. or area or 01 its authonltes, or concerning the delimitatiOn 01its frontiers or ccooca-ee. The mootion ol scecac companies or 01certain manufacturers' products does not imply that they are encIornedor fecorrmellded by the World Health Organization in preference to others of a smilar nature that are not mentioned Errors and omissions excepted, the rwnes 01proprietary products are distmguished by initial capnatjetters. The authors alone are responsible fOf the views expressed in this pubhcatlQfl. The copyright of figures and charts remains with the authors (see source 01charts and photographs. page 376--379) Format for bibliographic citations: Swerdlow S.H., Campo E., Harris N,L., Jaffe E.S" Pileri S.A., Stein H" Thiele J , Vardiman J.w. (Eds.): WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, IARC: Lyon 2008 IARC Ubrary Cataloguing in Publication Data WHO Classification of Tumours of Haematopo ietic and Lymphoid Tissues Edited by Swerdlow S.H.. Campo E., Harris NL , Jaffe E.S.• Piled SA, Stein H., Thiele J.. Vardiman JW. 1. Haematopoiehc System Neop lasms - genetics 2. Haematopoielic System Neop lasms - pathology I. Swerdlow. Steven H. ISBN 978-92-832-2431-0
  • Contents WHO Classifjcatioo 9 Summary table 10 Introduction to the classification of tumours of haematopoietic and lymphoid tissues 14 Introduction and overview of the classification of the myeloid neoplasms 17 2 Myeloproliferative neoplasms 31 Chronic myelogenous leukaemia. BCR-ABL 1positive 32 Chronic neutrophilic leukaemia 38 PoIycythaemia vera 40 Primary myelofibrOsis 44 Essenliallhrombocythaemia 48 Chronic eosinophilic leukaemia.NOS 51 Mastocytosis 54 Cutaneous mastocytosis 57 Systemic mastocytosis 58 Masl cell leukaemia 61 Mast cell sarcoma 61 Extracutaneous mastocytoma 61 Myeloproliferative neoplasm, unclassifiable 64 3 Myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA. PDGFRBOf FGFRl 67 4 MyelodysplasticJmyeloproliferative neoplasms 75 Chronic mveiomonocync leukaemia 76 Atypical ctYonicmyeloid leukaEmia. BCR-ABL1negative 80 Juvenile myelomonocytic leukaemia 82 MyelodysplastiC/myeloproliferalive neoplasm, urclasaifiable 85 5 Myelodysplastic syndromes 87 Myelodysplastic syndromes/neoplasms, overview 88 Refractory cytopenia with unilineage dysplasia 94 Refractory anaemia with ring side roblasts 96 Refractory cytopenia with multilineage dysplasia 98 Refractory anaemia with excess blasts 100 Myelodysplastic syndrome with isolated de l(5q) 102 Myelodysplastic syndrome, uncrasslttabte 103 Childhood myelodysplastic syndrome 104 Refractory cytopenia of childhood 104 6 Acute myeloid leukaemia (AML) and related precursor neoplasms 109 AML with recurrent genetic abnormalities 110 AML with t(8:21 )(q22:q22); RUNX1-RUNX1T1 110 AML with inv( 16)(p 13.1q22) or 1(16:t6)(p 13.1;q22): CBFB-MYH11 11 1 Acute orornveiocvnc leukaemia with t(15:17)(q22:q 12): PML-RARA 11 2 AML with us.11)(p22:q23): MLLT3-MLL 114 AML with t(6:9)(p23 :q34); DEK-NUP214 115 AML with inv(3)(q2 1q26.2) or t(3;3)( q2 1;q26.2); RPNt ·EVI1 116 AML (megakaryoblastic) with t(1;22)(p13;q13): RBM15-MKL 1 117 AML with mutated NPM 1 120 AMLwith mutated CEBPA 122 AML with myelodysplasia-related changes 124 Therapy-related myeloid neoplasms 127 Acu te myeloid leukaemia, NOS 130 AML with minimal differentiation 130 AML withOut maturation 131 AML with maturabon 131 Acute myelomonocytic leukaemia 132 Acute monoblastic and monocytic leukaemia 133 Acute erythroid leukaemia 134 Acute megakaryoblastic leukaemia 136 Acute basophilic leukaemia 137 Acute paomveosrs with myelofibrosis 138 Myeloid sarcoma 140 Myeloid proliferations related 10 Down synd rome 142 Transient abnOrmal myelopoiesis 142 Myeloid leukaemia associated with Dc:rwn syndrome 143 Blastic plasmacytoid dendritic cell neoplasm 145 7 Acute leukaemiasof ambiguous lineage 149 Acute undlHerentiated leukaemia 151 Mixed phenotype acute leukaemia wilh t(9;22)(q34;q 11.2): BCR-ABL 1 151 Mixed phenotype acute leukaemia with t(v:11q23): MLL rearranged 152 Mixed phenotype acute leukaemia , B/myeloid, NOS 152 Mixed phenotype acute leukaemia , T/myeloid, NOS 153 Mixed phenotype acute leukaemia, NOS· rare types 154 Other ambiguous lineage reukaerraes t 55 Natura! killer (NK)-celilympho blastic leukaemia/lymphoma 155 8 Introduction and overview 01 the classification of the lymphoid neoplasms 157 9 Precursor lymphoid neoplasms 167 B lymp hob lastic leukaemia/lymphoma, NOS 168 B lymphoblastic leukaemia/lymphoma with recurrent gene tic abn ormalities 171 B lymphoblastic leukaemiallymphoma with t(9:22)(q34;q 11.2): BCR-ABL 1 171 B lymphoblastic leukaemia/lymphoma with l(v:11q23): MLL rearranged 171 B lympho blastic leukaemiall ymphoma with t(12:21)(p13;q22): TEL-AMLl (ETV6--RUNX1) 172 B lymphoblastic leukaemia/lymphoma with hyperdiploidy 173 B lymphoblastic leukaemiallymphoma with hypodiplOidy (Hypodiploid ALL) 174 B lymphoblastic leukaemiallymphoma with t(5; 14)(q31;q32); IL3-IGH 174 B lymphoblastic leukaemiallymphoma with t(1;19) (q23:P13.3): E2A-PBX1(TCF3-PBXI) 175 T lymphoblastic leukaemiallymphoma 176
  • Enteropathy-associated t-een lymphoma 289 Hepatosplenlc t -een lymphoma 292 Subcutaneous panniculitis-like t-een lymphoma 294 Mycosis fungoides 296 Sezary syndrome 299 Primary cutaneous CD30 positive t-een Iymphoprolilerative disorders 300 Primary cutaneous peripheral t-een lymphomas, rare subtypes 302 Primary cutaneous garnna-della T-cenlymphoma 302 Primary cutaneous COB positive aggressive epidermotrop ic cytotoxic T-celt lymphoma 303 Primary cutaneous CD4 positive small/medium T-cell lymphoma 304 Peripheral t-een lymphoma. NOS 306 Angioimmunoblastic t-een lymphoma 309 Anaplastic large cell lymphoma. AlK positive 312 Anapla stic large cell lymphoma . ALK negative 317 12 Hodgkin lymphoma 321 Introduction 322 Nodular lymphocyte predominant Hodgkin Iymptuna 323 Classical Hodgkin lymphoma. introduction 326 Nodular sclerosis classical Hodgkin lymphoma 330 Mixed cellularity classical Hodgkin lymphoma 331 Lymphocyte-rich classical Hodgkin lymphoma 332 lymphocyte-depleted classical Hodgkin lymphoma 334 13 1rnmunodeficiency-associated Iymphoproliferative disorders 335 Lymphoproliferative diseases associated with primary immune disorders 336 Lymphomas associated with HIV infection 340 Post-nansotanttsmpnooronterauve disorders (PTlD) 343 Plasmacytic hyperp lasia and infectious- rrooooocieose-uke PTlD 345 Polymorphic PTlO 346 Monomorphic PTlO 347 Classical Hodgkin lymphoma type PTLO 349 Other iatrogenic immunodeficiency-associated Iymphoproliferative disorders 350 , • 10 Mature B-ceUneoplasms 179 Chronic lymphocytic leukaemia Ismail Iympt'locytic lymphoma:f 180 s-een prolyrT¢lhocytic leukaemia 183 Splenic B-cell marginal zone lymphoma 185 Hairy cell leukaemia 188 Splenic B-cell Iymphomalleukaemia, unclassiliable 191 Splenic diffuse red pulp small B-ceil lymphoma 191 Hairy cenleckaeme-....anent 192 lymphoplasmacytic lymphoma 194 Heavy chain diseases 196 Gamma heavy chain disease 196 Mu heavy chain disease 197 Alpha heavy chain disease 198 Plasma cell neoplasms 200 Monoclonal gammopathy 01undetermined significance (MGUS) 200 Plasma cell myeloma 202 Solitary plasmacytoma of bone 208 Extraosseous plasmacytoma 208 Monoclonal immunoglobulin deposition diseases 209 Extranodat marginal zone lymphoma of mucosa- associated lymphoid tissue (MALT lymphoma) 214 Nodal marginal zone lymphoma 218 Follicular lymphoma 220 Primary cutaneous follicle centre lymphoma 227 Mantle cell lymphoma 229 Diffuse large B-celllymphoma (DLBCl), NOS 233 T celilhistiocyte-rich large B-cell lymphoma 238 Primary DlBCL of the CNS 240 Primary cutaneous DlBCl . leg type 242 EBV positive DLBCl of the elderly 243 DLBCL associated with chronic inflammation 245 Lymphomatoid granulomatosis 247 Primary mediastinal (thymic) large B-celilymphoma 250 Intravescurer large B-celi lymphoma 252 ALK positive large Been lymphoma 254 Plasmablastic lymphoma 256 large a-ceu lymphoma arising in HHV8-associated multicentric Castleman disease 258 Primary effusion lymphoma 260 Burkitllymphoma 262 B-cel1lymphoma, unclassiliable, with features intermediate between DLBCL and Burkitllymphoma 265 B-ceillymphoma, unctessmebie.with features intermediate between OLBCl and classical Hodgkin lymphoma 267 11 Mature T- and NK-cell neoplasms 269 r-cea prolymphocytic leukaemia 270 t-een large granular lymphocytic leukaemia 272 Chronic Iymphoproliferative disorder of NK cells 274 Aggressive NK cell leukaemia 276 Epstein-Barr virus (EBV) positive t-een Iymphoprolilerative diseases of childhood 278 Systemic EBV+ t-een Iymphoproliferalive disease of childhood 278 Hydroa vacclnrtorrne-uke lymphoma 280 Adull T-ceil leukaemia/lymphoma 281 Extranodal NK/T-cell lymphoma. nasal type 285 14 Histiocytic and dendritic cell neoplasms Introduction Histiocytic sarcoma Tumours derived from langerhans cells Langerhans cell histiocytosis Langerhans cell sarcoma Interdigitating dendrit ic cell sarcoma Follicular dendritic cell sarcoma Other rare dendritic cell tumours Disseminated juvenile xanthogranuloma Contributors Clinical advisory oorrrnittee Source of Charts and photographs References Subject index NOS, no! otherwise specified 353 354 3S6 358 3S8 360 361 363 365 366 369 374 376 300 429
  • - WHO Classification 4th Edition / / - -.,.e" / , ~ ~~...,...,... -~ /,f / -~ ~ _....i? ~.,.~ -
  • WHO Classification of tumours of haematopoietic and lymphoid tissues MYELOPROLIFERATIVE NEOPLASMS MYELODYSPLASTIC SYNDROMES Chronic myelogenous leukaemia, BCR-ABL 1 positive Chronic neutrophilic leukaemia Polycythaemia vera Primary myelofibrosis Essential thrombocythaemia Chronic eosinophilic leukaemia, NOS Mastocytosis Cutaneousmastocytosis Systemic mastocytosis Mast cell leukaemia Mastcell sarcoma Extracutaneous mastocytoma Myeloproliferative neoplasm, unctassitlable 987513 9963/3 9950/3 9961/3 996213 9964/3 974011 9741/3 974 213 9740/3 9740/1 9975/3 Refractory cytopenia with unilineage dysplasia Refractoryanaemia Refractory neutropenia Refractory thrombocytopenia Refractoryanaemia with ring sideroblasts Refractory cytopenia with multitineage dysplasia Refractoryanaemia with excess blasts MyelodysplasUc syndrome associated with isolated del(Sq) Myelodysplasticsyndrome, uncJassifiable Childhood myelodysplasuc syndrome Refractorycytopenia of childhood 9980/3 9991/3 9992/3 9962/3 9965/3 9983/3 9966/3 9969/3 996513 MYELODYSPLASTIC/MYELOPROLIFERAnVE NEOPLASMS 9869/3 9696/3 9666/3 9697/3 986513 9671/3 9911/3 9861/3 9661/3 AML with recurrent genetic abnormalities AML with t(6;21)(q22;q22); RUNXI-RUNX1Tl AML with inv(16)(pI 3.1q22 ) or t(16;16)(pI3.1;q22); CBFB-MYHl1 Acute promyelccytlc leukaemia with t(15;17)(q22;qI2); PML-RARA AML with t(9;11)(p22 ;q23); MLLT3-MLL AML with 1(6;9)(p23;q34); DEK-NUP214 AML with inv(3)(q21q26.2) ort(3;3)(q21;q26.2); RPNI-EV/1 AML (megakaryoblastic) with t(I ;22)(pI 3;qI 3); RBMI5-MKLI AML withmutated NPM1 AML wrlh mutatedCEBPA ACUTE MYELOID LEUKAEMIA (AML) AND RELATED PRECURSOR NEOPLASMS 9965/3 9967/3 9966/3 967613 9946/3 9945/3Chronic myetcmonocytic leukaemia Atypical chronic myeloidleukaemia. BCR-ABL 1negative Juvenile myelomonocyticleukaemia MYELOID AND LYMPHOID NEOPLASMS WITH EOSINOPHILIA AND ABNORMALITIES OF PDGFRA, PDGFRB OR FGFRI Myeloid and lymphoid neoplasms with PD GFRA rearrangement Myeloid neoplasms with PDGFRB rearrangement Myeloid and lymphoid neoplasms with FGFR1 abnormalities 996213 Myelodysplasticlmyeloproliferative neoplasm. unclassifiable 9975/3 Refractoryanaemia with ringsideroblasts associated WIth marked thrombocytosis AML with myelodysplasia-related changes 969513 Therapy-related myeloid neoplasm s 992013 10 WHOctassrtceton
  • Myeloid proliferations related to Down syndrome Transient abnormal myelopoiesis 989811 Myeloid leukaemia associated with Down syndrome 9898/3 Acute myeloid leukaemla",NOS 9861/3 AML with minimal differentiation 987213 AML without maturation 9873/3 AML with maturation 9874/3 Acute myelomonocytic leukaemia 9867/3 Acute monoblastic and monocytic leukaemia 9891/3 Acute erythroid leukaemia 984013 Acute megakaryoblastic leukaemia 99 10/3 Acute basophilic leukaemia 987013 Acute panmyelosis with myelofibrosis 993113 Myeloid sarcoma 993013 B lymphoblastic leukaemia/lymphoma with recurrent genetic abnormalities B lymphoblastic leukaemiaflymphoma with 1(9;22)(q34;ql 1.2); BCR-ABU 9812/3 B lymphoblastic leukaemiallymphoma with t(v;11q23); MLL rearranged 981Y3 B lymphoblastic leukaemiallymphoma with 1(12;21)(p13;q22); TEL-AMU (ETV6-RUNX1) 9814/3 B lymphoblastic leukaemiallymphoma with hyperdiploidy 981513 B lymphoblastic leukaemiallymphoma with hypodiploidy (hypodiploid ALL) 981613 B lymphoblastic leukaemiallymphoma with t(5;14Xq31;q32); IL3-IGH 9817/3 B lymphoblastic leukaemia/lymphoma with t(1;19)(q23 ;p13.3); E2A-PBXl (TCF3-PBX1) 9818/3 T lymphoblastic leukaemia/lymphoma 9837/3 982313 983313 968913 9940/3 9591/3 9591/3 9591/3 9671/3 9761/3 9762/3 9762/3 9762/3 9762/3 9732/3 9731/3 9734/3 Splenic B-cell fymphomalleukaemia, unclassifiable Splenic diffuse red pulp small B-cell lymphoma Hairy eel/leukaemia-variant MATURE B-CELL NEOPLASMS Chronic lymphocytic leukaemia! small lymphocytic lymphoma B-cell prolymphocytic leukaemia Splenic Bccell marginal zone lymphoma Hairy cell leukaemia Lymphoplasmacytic lymphoma waldenstrom macroglobulinemia Heavy chain diseases Alpha heavy chain disease Gamma heavy chain disease Mu heavy chain disease Plasma cell myeloma Solitary plasmacytoma of bone Extraosseous plasmacytoma 9727/3 98 11/3 9807/3 980613 9808/3 9809/3 Mixed phenotype acute leukaemia with t{v;11q23); MLL rearranged Mixed phenotype acute leukaemia, B/myeloid, NOS Mixed phenotype acute leukaemia, Tfmyeloid, NOS Natural killer (NK) cell lymphoblastic !euKaemiallymphoma ACUTE LEUKAEMIAS OF AMBIGUOUS LINEAGE Acute undifferentiated leukaemia 9801/3 Mixedphenotype acute leukaemia with t(9;22)(q34;q 11.2); BCR-ABL1 PRECURSOR LYMPHOID NEOPLASMS B lymphoblastic leukaemiaflymphoma B lymphoblastic leukaemiall ymphoma, NOS Blastic plasmacytoid dendritic cell neoplasm WHOclassification 11
  • - 965313 965213 965113 9663/3 9659/3 9650/3 9718/3 9726/3 9709/3 9709/3 970213 970513 9714/3 970213 970813 970013 970113 9718/1 HODGKIN LYMPHOMA Nodular lymphocyte predominant Hodgkin lymp homa Classical Hodgkin lymphoma Nodular sclerosis classical Hodgkin lymphoma l ymphocyte-rich classica l Hodgkin lymphoma Mixed cellularity classical Hodgkin lymphoma l ymphocyte-depleted classical Hodgkin lymphoma Primary cutaneous CD30 positive F-eel! Iymphoproliferative disorders lymphomatoid papulosis Primary cutaneous anaplastic large cell lymphoma Primary cutaneous qamma-delta r -ceuivmpncma Primary cutaneous COB positive aggressive epidermotropic cytotoxic T-cefl lymphoma Primary cutaneous CD4 positive smalVmedium T-cell lymphoma Peripheral Tccelllympboma, NOS Angioimmunoblastic 'l-cetl Iyrnphoma Anaplastic large cell lymphoma, ALK positive Anaplastic large cell lymphoma, ALK negative Systemic EBV positive T-celllymphoproliferative disease of childhood 9724/3 Hydroa vacciniforme-like lymphoma 972513 Adult T-cell ieukaemia/lymphoma 9827/3 Extranodal NKIT cell lymphoma, nasal type 9719/3 Enteropamy-associated T-cell lymphoma 9717/3 Hepatosplenic T-cell lymphoma 971613 Subcutaneous panniculitis-like T-cell lymphoma Mycosis fungoides Sezary syndrome 983113 9948/3 9678/3 9687/3 968 0/3 9679/3 971213 9737/3 9735/3 9699/3 9699/3 9699/3 9690/3 9690/3 959713 967313 Aggressive NK cell leukaemia MATURE T-CELL AND NK·CELL NEOPLASMS j-cen prolymphocytic leukaemia 9834/3 'f-celllarqe granular lymphocytic leukaemia 9831/3 Chronic Iymphoproliferative disorder of NK..cells Primary effusion lymphoma Burkitt lymphoma B-ceillymphoma, unclassifiable, with features intermediate between diffuse large g-ceu lymphoma and Burkitt lymphoma B-ceil lymph oma , unclassifiable, with features intermediate between diffuse large 8-cell lymphoma and classical Hodgkin lymphoma 9596/3 Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) Diffuse large B-eelllymphoma (OlBCl), NOS 968013 T-ceillhistiocyte rich large B-eelilymphorna 9688/3 Primary DLBCl of the CNS 968013 Primary cutaneous DlBCl. leg type 9680/3 EBV positive OLBCL of the elderly 9680/3 Ol BCl associated with chronic inflammation 968013 l ymphomatoid granulomatosis 9766 /1 Primary mediastinal (thymic) large B-celllymphoma Intravascular large B-cell lymphoma AlK positive large B-cell lymphoma Plasmablastic lymphoma l arge Bccell lymphoma arising in HHV8- associated multicentric Castleman disease 9738/3 Nodal marginal zone lymphoma Paediatric nodal marginal zone lymphoma Follicular lymphoma Paediatric folliculaf lymphoma Primary cutaneous follicle centre lymphoma Mantle cell lymphoma 12 WHO ciassitcenon I ~l.. _
  • HISTIOCYTIC AND DENDRITIC CELL NEOPLASMS Histiocytic sarcoma 9755/3 l angerhans cell histiocytosis 975 1/3 langerhans cell sarcoma 9756/3 Interdigitating dendritic cell sarcoma 9757/3 Follicular dendritic cell sarcoma 975813 Fibroblastic reticular cell tumour 9759/3 Indeterminate dendritic cell tumour 9757/3 Disseminated juvenile xanthogranuloma POST·TRANSPLANT LYMPHOPROUFERATIVE DISORDERS (PTLO) Early lesions P1asmacytic hyperplasia 9971/1 Infectious mononucleosis-like PTLD 9971/1 Polymorphic PTLO 9971/3 Monomorphic PTlO (B- and TINK-cell types)' Classical Hodgkin lymphoma type PTLO'" NOS, not otherwise specified. The italicized numbers are provisiona l codes for the 4th editionof lCD-D. While they are expected to be incorpo- ratedin the next ICD-O edition, they currentty remain subjectto changes. Theitalicized histologic types are provisional entities , for which the WHO Working Group fell there was insufficient evidence to recognize as distinct diseases at this time. "These lesions are classified according to the leukaemia or lymphoma to which they correspond, and are assigned the respectivetCO-G code. WHO classification 13
  • Introduction to the WHO classification of tumours of-haernatopoletlc and lymphoid tissues NL Harris E. Campo E.S. Jaffe SA Pileri H. Stein S.H. Swerdlow J Thiele Jw. Vardiman ... . Why classify? Classification is the lan- guage of medicine: diseases must be described , defin ed and named before they can be diagnosed, treated and studied. A consensus on definitions and terminol- og y is essential for both clinical practice and investigation. A classification should contain diseases thai are clearly defined. clinically distinctive. norKlVerlappi ng (mu- tually excllsive) and that together comprise all known entities (collectively exhaustive). II should serve as a basis lor future inves- tigation. and should be able to incorporate new information as it becomes available. Classification has two aspects: clas s dis- covery - the proces s of identifying cate- gories of diseases, and class prediction - the process of determining which cere- gory an individualcase belongs to. Pamer- ogi sts are critical to both processes. The World Health Organization (WHO) Classification of Tumours of the Haema- topoietic and Lymp hOid Tissues (4th Edi- tion) was a coll aborative project of the European Association for Haematopathol- ogyand the Society lor Hematopathology. It is a revision and update of the 3rd Edi- tion 11039}. which was the first true worldwide consensus classification of baematoiocic malignancies. The update, which began in 2006, had an a-membe r steering committee composed of members of both societies, The Steering Comminee, in a series of meetings and discussions, agreed on a proposed list of diseases and chapters and selected authors. with input from both societies. As with the WHO 3fd edition 18971. the advice of clin - ical haematologists and oncologists was obtained. in order to ensure that the clas- sification will be clinically useful. TwoClin- ical Advisory Committees (CAG). one for myeloid neoplasms and other acut e leukaemias and one for lymphoid neo- plasms. were convened, The mee tings were organized around a series of questions, inc luding disease definitions, nomenclature, grading. and clinical rele- vance. The committees were able to reach consensus on most of the ques- tions posed. and muc h of the input of the 14 Introduction to the classification committees was incorporated into the class ification. Over 130 pathologists and haem atologists from around the world were involved in writing the chapters. A consensus meeting was held at the head- quarters of the IARC in Lyon, France. to make final decisions on the classification and the content of the book. The WHO classification of tumours of the haematopoietic and lymphoid system is based on the principles initially defined in the "Revised European-American Classi- fication of Lymphoid Neoplasms" (REAL). from the Interna tional Lymphoma Study Group (ILSG) 18981. In the WHO classifi- cation, these principles have also been applied to the class ification of myeloid and histiocy tic neoplasms, The gu iding principle of the REAL and WHO classifi- cations is the attempt to define "real" d iseases that can be recognized by pathologists with available techniques. and that appear be distinct clinical enti- ties. There are 3 important components to this process First. recognizing that the underlying causes of these neo plasms are often unknown and may vary, this ap- proach to classifica tion uses all available information - morphology, immunophe- notype, genetic features, and cl inical fea- tures- to define diseases. The relative impo rtance of each of these features varies among diseases, depend ing upon the state of current knowledge, and there is therefore no one "gold standard," by which all diseases are defined . Second. recognizing that the com plexity 01 the field makes it impossible for a single expert Of small g roup to be comptetely authoritative, and that broad agreement is necessary if a classificati on is to be ac- cepted, this ctassrncanon relies on build- ing a consensus among as many experts as possible on the definition and nomen- clature of the diseases, We recognize that com promise is essential in order to arrive at a consensus, but believe that the only thing worse than an imperfect classifica- tion is multiple competing classifi cations. Finally. while pathologists must take primary responsibility for developing a classification, involvement of clinicians is essential to ensure its usefulness and ac- ceptance in daily practice 18971. At the lime of publication of the WHO classi fication (3rd edition), proponents of other classifi- cations of haematologic neoplasms agreed to use the new classification, thus ending decad es of controversy over the classifi- cation of these tumours 147. 478. t 89. 1B9A, 190, 673,7750 , 1344A. 181981, As indicated above , there is no one -gold standard ," by which all diseases are defined in the WHO classification. Mor- pholog y is always important, and many diseases have characteristic or even di- agnosti c morphologic features, Immune- phe notype and genetic features are an important part of the definition of tumours of the naematopolettc and lymphoid tissues, and the availability of this infor- mation makes arriving at consensus defi- nitions easier now than it was when only subjective morphologic criteria were available. lrrmunophenotyping studies are used in routine diagnosis in the vast majority of haematolog ic malignancies, both to determine lineage in malignant processes and to distinguish benign lrom malignant processes. Many diseases have a characteristic immunophenotype. such that one would hesitate to make the diagnosis in the absence of the immune- phenotype, while in others the immuno- onenotvpe is only part of the diagnosis, In some lymphoid and in many myeloid ne0- plasms a specific genetic abnorma lity is the key defining criterion, while etters lack specific known genetic ebnomantes. Some genetic abnormalities, while char- acteri stic of one disease, are not specific (such as MYC. CCND 1or BCl2rearrange- ments or mutations in JAK2). and others are prognostic factors in several diseases (such as TP53 mutations or FLT3-ITO), The inc lusion of jr munoohenotvoc lea- tures and genetic abnormalities to define entities not only provides objective criteria for disease recogni tion but has identified antigens, genes or pathways that can be targeted for therapy; the success of rituximab, an anti-CD20 molecule, in the
  • treatment of. B-cel! neoplasms, and 01 imatinib in the treatment of leukaemias as- sociated with ABL 1 and oth re!lrrange- ments involving tryoene kinase genes are testament to this approach. Finally. some diseases require knowledge of clinical features - age, nodal versus extranodal presentanon. specific anatomic site. and history 01 cytotoxic and other therapies - to make the diagnosis. Most 01 the dis- eases described in the WHO classification are considered to be distinct enti ties; however. some are not as clearly defined, and these are listed as provisional entities, In addition . borderline categories ha....e been created in this edition for cases that do not c learly fit into one category, so that well-defined categories can be kept homogeneous, and the borderline cases can be studied further. The WHO classification stratifiesneoplasms primarily according to lineage: myeloid, lymphoid, and histiocyticfdendritic cell. A normal counterpart is postulaled lor each neoplasm. While the goal is to define the lineage of each neoplasm, lineage plas- ticity may occur in precursor or immature neoplasms, and has recently been identi- fied in some mature haematotymphoid neoplasms , In addition, genetic atooe- rreuues such as FGFR1, PDGFA and PDGFB rearrangements may give rise to neoplasms 01either myeloid or lymphoid lineage associated with eosinophilia; these disorders are now recognized as a separate group. Precursor neoplasms (acute myeloid reukaemes. lymphoblastic Iymphomasfleukaemias, acute reukaerraas 01ambiguo us lineag e, and blastic plas- macytoid dendritic ce ll neoplasm) are considered separately from more mature neoplasms [myeloproliferative neoplasms (MPN). myelodysplastic/myeloproliterative neoplasms, myelodysplastic syndromes , mature (peripheral) B-cell and T/NK-cell neoplasms, Hodgkin lymphoma. and his- Iiocyteldeodritic-cell neoplasms]. The ma- ture myeloid neoplasms are stratified according to their biological features (myeIopl'oIiferative, with effective baereio- poiesis. ....ersus myelodysplastic, with in- effective neematcootesfs. as welt as by genetiC features). Within the mature lym- phoid neoplasms, the diseases are listed broadly accord ing to clinical presentation (disseminated often leukaemic, extran - coat. indolent. aggressive). and to some extent according to stage of differentiation when this can be postulated: the order of listing is in part arbitrary, and is not an integral part of the classification. The 4th edition of the WHO classification incorpo rates new information that has emerged from basic and clinical in....estr- gations in the interval since publication of the 3rd edition. It includes new defining criteria for some disease s, as well as a number of new entities. some defined by genetic criteria - particularly among the myeloid neoplasms- and others by a combination of morphology. immunophe- ootype . and clinical features. The frequent application of immunophenotyping and genetic studies to peripheral blood, bone marrow, and lymph node samp les has also led to the detection of small clonal populations in asymptomatic pe rsons. These include small clones of cells with the BCR-ABL 1 translocation seen in chronic myelogenous leukaemia. small clones of cells with BCL2-IGH rearrangement. and small populations of cells that have the immuoopheootype of chronic lymphocytic leukaemia (e l l ) or follicular lymphoma (monoc lonal B lymphocytosis, follicular lymphoma-in Situ, paediatric follicular hy- perplasia WIth monoclonal B cells). In many case s. it is not clear whether these represent earty involvement by a neoplasm, a precursor iesoo. or an inconsequential find ing. These situations have some analogies to the identification of small monoclonal immunoglobulin components in serum (monoclonal gammopathy of unknown significance), The chapters on these neoplasms include recommenda- tions for dealing with these situations. The recommendations of international con - sensus groups have bee n considered. with regard to criteria for the d iagnosis of e ll, plasma cell myeloma, Waldenstr6m macroglobulinemia, and new subtypes of cutaneous lymphomas, as well as in the development of new algorithms for the diagnosis of MPN . A critical feature of any class ification of diseases is that it be periodically reviewed and updated to incorporate new informa- tion. TheSocietyfor Haematopathology and the European Association for Haemato- pathology now have a more than to-year record of couebceaton and cooperation in this effort. The societies are comm itted to updating and revising the classification as needed. with input lrom clinicians and with the collaboration of the WHO. The experience of developing and updating the WHO classification has produced a new and exciting degree of cooperation and conmunication among patholog ists and oncologists from around the world . which stould facilitate continued progress in the understand ing and treatment of haematotogic manqnaocies . Themullipa- rameter approach to classification, with an emphasis on defining real disease entites. that has been adopted by the WHO classification, has been shown in international studies 10 be reproducible: the diseases defined are clinically dis- ttnct ive. and the uniform definitions and terminology facilitate the interpretation of clinical and translational studies 151, 791. In addition, accurate and precise classifi- cation of d isease entities has facilitated the discovery of the genetic bas is of myeloid and lymphoid neoplasms in the basic science laboratory Introdu ction to the classification 15
  • -, CHAPTER 1 Introduction and Overview of the Classification of the Myeloid Neoplasms • " ) •
  • Introduction and overview of the classification of the myeloid neoplasms J.w. Vardiman A.D. Brunning D.A. Arter M.M.Le Beau A. Porwit A. retten C.D. Bloomfield J. Thiele The WHO Classification of Tumours of the Haematopoietic and Lymphoid Tissues (3rd edition) published in 200 1 reflected a paradigm shift in the approach to clas- sification of myeloid neoplasms {1039). For the first time. genetic information was in- corporated into diagnostic algorithms provided lor the various entities. The pub- lication was prefac ed with a comment pred icting future revisions necessitated by rapidly emerg ing gen elic information. The cu rrent revision is a commentary on the significant new molecular insights mat have become avail abl e since the publi- cation of the last ctass'ncauon. The first entity described in this mono- graph. chronic myelogenous leukaemia (CML) remains the prototype for the iden- tification and classification of myeloid neoplasms This leukaemia is recognized by its c linical and morphologic features, and its natural progression is character- ized by an increase in blasts of myeloid, lymphoid or mixed myeloid/lymphoid immunophenotype. It is always associ- ated with the BCR·ABL 1fusion gene that results in the production 01 an abnormal protein tyros ine kinase (PTK) with en- hanced enzymatic activity. This protein is sut tcrentto cause the leukaemia and also provides a targ et for protein tyrosi ne kinase inhibi tor (PTKI) therapy that has prolonged the lives of thousands of pa- tients with this often tatal illness {6151. This successful integration of cl inical , morphologic and genetic information em- bodies the goal of the WHO classification scheme. In this revision. a combination of clinical, morpholog ic . immunophenotypic and genetic features is used in an anerrcttc define disease entities , such as CML, that are biolog ically homogeneous and clini- cally relevant - the same approach used in the 3rd ed ition of the classification. Although the previous scheme began to open the door to including genetic ab- normalities as criteria to classi fy myeloid neoplasms, this revision firmly acknowl- edges that as in CML, recurring genetic abno rmalities provide not only objec tive criteria for recognition of speci fic entities but also identification of abnormal gene product s or pathways that are potential targets for therapy. One example in this revised scheme is the addition of a new subgroup of mye loid neoplasms (Tabte 1.01) assoc iated with eos inoph ilia and chromosomal ab normalities that involve the oiateiet-oenved growth factor receptor ..' Table 1.01 Themyeloid neoplasms' majorsul:9'OUJlS and dal;U::i tstic features at~ 0..... 8Mctllularity '10 MIrf'OW bluts .- .........., HatrnatopOitsit ...."""" -MPN Usually increased. tbmaJ or sIighlIy """'" G••,,,''''''', En-. VanabIe;008 or Co<m>oo often normalin ET increased: <10%in -- """..-dI'onic phase relabYe/y normal, IifIeage usually """""""", irullallyincreased """""'"MyeIoidIIymphoid Increased Normal or $IigM~ Present Relatively normal Elfectrve Eosinophilia Com~ neoplasmswith increased: <20% irl j~t 5x10ir1.) eosinophiliaand abriof· cnronc phase maliliesof PDGFRA. PDGFRB Of FGFRI MOS "''''as." Nom1al or increased: Preserlt ~lasia inoreor Inel!&Cti'Ie Cytopenia(s) U _ =- ""'. more myeloid lineage ~aror """""'"M''''''PN """'... -,,- """'" Usually oneormae Moy""Y ...... IariabIe. WBC Co<m>oo incl'eased;<20'10 -- ...... ..--......_""rrft'!lal cIyspIaSIa """"....... _>2ll%. "",", MayOf may J'IOl be ........ WllC_ """'- eQPl in some cases ......, """"""'" ore"ect1ve ..-......'l'Illh specific cybJeneIlc -... dyspIaslai'loneor ...-abnorrnaIilies or in -...... ......some cases of erylhroIeukaemia Mf)N, myeloproliferative neoplasms: MDS, myelod)'spla:slic syndromes;MDSlMf)N, myeIodysplasbcJmyeloprolifefalive neoplasms: AMl, ICIJIe myeloid leukaemia; ET, esseflIlaj Ihfombocylhaemia, JMML.ju¥&nile myelomonocytic leukaemia, wec.wniIe bloocI e&II$. 18 Introduction and overview of the c lassification of the myeloid neoplasms
  • ] alpha (PDGFflA) Ofplatelet derived growth factor receptor beta (PDGFRB) genes -a subgroup defined larger9 by genetic events that lead to constitutive act ivation of the receptor tyrosine kinase, PDGFA, and that respond to PTKI therapy {13 1, 466. 8121. Similar examples are found throughout the classification in each major subgroup, and include not only neoplasms associated with rmcroscopr- cally recog nizable chromosomal abnor- malities but also with gene mutations without a cytogenetic correlate as weu. On the other hand . the importance 01 careful clinical, morphological and im- munophenotypic characterization of each myeloid neoplasm and coeretanoo with the genetic findings cannot be over- emphasized. The discovery of activating JAK2 mutations has revolutionized the approach to the diagnosis of the myelo- proliferative neoplasms (MPN) 1163, 1044, 1186,12681. Yet JAK2mutatiQns are not specific for any single clinical or morpho- logic MPN phenotype, and are also reported in some cases 01 myelodysplas- tic syndromes (MDS), myeiooysplasnc/ myeloproliferative neoplasms (MDSlMPN) and acute myeloid leukaemia (AMl). Thus, an integ rate d, multidisciplinary approach is necessary for the classification of myeloid neoplasms. With so much yet 10 learn, there may be some 'missteps" as traditional approaches to categorization are fused with more rrcecuarfy-orentec clessifcatonschemes, Nevertheless, this revi sion of the WHO classification is an attempt by the authors, editors and the clinic ians who served as members of the Clinica l Advisory Com- mittee (CAC ) to provide an "evidence- based" classification that can be used in daily practice for therap eutic decisions and yet provide a flexible framework for integration of new data, Prerequisites for classification ofmyeloid neoplasms by WHO criteria The WHO classification of myeloid neo- plasms relies on the morphologic, cyto- chemical and immunophenotypic features of the neoplastic cells to establish thei r lineage and deg ree 01 maturation and to decide whether cellular prolife ration is q101ogically normal or dysplastic or esecuve or ineffective . The classification is based on cr iteria applied 10 initial spec- imens obtained prior to any definitive ther- apy, including growth lactor therapy, for the myeloid neoplasm. The blast percentage in the peripheral blood , bone marrow and other involved tissues remains of practical impo rtance to categorize myeloid neo- plasms and to judge their progression. Cytogenetic and molecular genetic stud- ies are requ ired at the time of diagnosis not only for recoqr nton 01 specific genet- ically defined entities, but for establiShing a baseline against which futu re studies can be judged to assess disease pro- gression. Beca use of the multidisciplinary approach required to diagnose and clas- sify myeloid neoplasms it is recomnended thaI the various diagnostic studies be correlated with the clinical findings and reported in a single, integ rated report. If a definitive classification cannot be reached the report should indicate the reasons why and provide guidelines for additional studies that may clarify the diagnosis. To obtain consistency, the following guidelines are recommended for the eval- uation of specimens when a myeloid neo- plasm is suspected to be present. It is assumed that this evalua tion will be per- formed with full knowledge of the clinical history and pertinent laboratory data. Morphology Peripheral blood: A perip heral blood (PB) smear should be exa mined and co rre- lated with results of a co mplete blood count. Freshly mad e smea rs should be sta ined with May-Gnmwald -Giernsa or Wright-Giemsa and examined for wh ite blood ce ll (WBC) , red blood ce ll (ABC) and platelet abnormalities It is important to ascerta in that the smears are well- stained, Evaluation of neutrophil granularity is important when a myeloid disorder is suspected; designation of neutrophils as abnormal based on hypog ranular cyto- plasm alone shoul d not be considered unless the stain is well-controlled . Manual 2OO-cell leukocyte di fferentials of PB smears are recommended in patients with a myeloid neoplasm when the WBC count permits. Bone manowaspirate: Bonemarrow (BM) aspirate smears should also be stained with May-GrQnwald-Giemsa or Wright- Giemsa for optimal visualization of cyto- plasmic granules and nuclear chromatin. Because the WHO Classification relies on percentages of blasts and other specific 11111111 111I 1111 1111 111111 4 5 6 F'S!. 1.01 Bone marrow tIeI:Me biopsy, Bone marfOW b'ephinebiopsies should be alleast 1.5em inlength and ollt<w1ed at right angles10 the cortical bone. cells to categorize some eoutes. it is rec- ommended that 500 nucleated BM cells be counted on cellular aspirate smears in an area as close to the particle and as undiluted with blood as possible. Countll"lQ from multiple smears may reduce sam- pling error due to irregular distribution of cells. The cells to be counted include blasts and promonocytes (see definition below) . pronveocvtes. myelocytes, meta- myelocytes, band neutrophils, segmented neutrophils, eosiropnns. basophils, fTlQIlO- cytes , lymphocytes. plasma cells, erythrOid precursors and mast cells. Megakaryo- cvtes. including dysplastic forms. are not included. If a concomitant non-myeloid neoplasm is present, such as plasma ceu myeloma, it is reasonable to exclude those neoplastic cells from the coun t used to evaluate the myeloid neoplasm. If an aspirate ca nnot be obtained due to fibrosis Of ce llular packing, touch prepa- rations of the biopsy may yield valuable cytolog ic information, but differential co unts from touch preparations may not be representative . The differential counts obtained from marrow aspi rates should be compared to an estimate of the pro- portions of cells observed in available biopsy sections, Bone marrow trephine biopsy: The contri- bution of adequate 8M biopsy sections in the diagnosis of myeloid neoplasms can- not be overstated. The trephine biopsy provides information rega rding overall cellularity and the topog raphy, proportion and maturation of baematopolenc cells , and allows evaluation of 8M stroma. The biopsy also provides material for immuno- histochemical studies that may have diagnostic and prognostic importance. A biopsy is essential whenever there is myelofibrosis,and the classificationof sore entities, partiCularly MPN, relies heavily on trephine sections, Thespecimen must be Introduction and overview of the ctassncauoo at the myeloid neoplasms 19
  • adeq uate, Iaken at right angle from the cortica l bone and at least 1.5 cm in length to enable the evaluation of at least 10 par- tially preserved inter-trabecular areas. It should be well-fixed, thinly sectioned at 3-4 micra, and stained with haematoxylin and eosin and/or a stain such as Giemsa that allows lor detailed morphologic eval- uation. A silver impregnation method for reticulin fibres is recommended and marrow fibrosis graded according to the European consensus scoring system 122141, A periodic acid-Schitt (PAS) stain may aid in detection 01 megakaryocytes. Immunohistochemical (IHe) study of the biopsy is often indispensable in the eval- uation of myeloid neoplasms and is dis- cussed belOw, Blasts: The percentage of myeloid blasts is important for dl8gnosis and ctasstcaton of myeloid neoplasms, In the PB the blast percentage should be derived from a 200-cell leukocyte differential and in the 8M from a 500-cell count of cellular 8M aspirate smears as described above. The blast percentage derived 'rom the 8M aspirate should correlate With an estimate of the blast percentage in the trephine biopsy. although large focal clusters or sheets 01blasts in the biopsy should be regarded as possible disease progression. Immunohistochemical staining of the BM biopsy for CD34+ blasts often aids in the correlation of aspirate and trephine biopsy findings, although in some myeloid neo- plasms the blasts do not express CD34, Flow cytometry determination of blast percentage should not be used as a sub- stitute for visual inspection. The specimen for flow cytometry is otten haemoouute. and may be affected by a number of pre- analytic variables. and as noted for the biopsy. not all blasts express CD34. Myeloblasts. monoblasts and megakary<> blasts are included in the blast count. Myeloblasts vary from slightly larger than mature lymphocytes to the size of mono- cvtes or larger. with moderate to abun- dant dark blue to blue-grey cytoplasm. The nuclei are round to oval with finely granul ar chromatin and usually several nucleoli. but in some nuclear irregularities may be prominent. The cytoplasm may contain a few azurophil granules(Fig 1,03), Monoblasts are large cells with abundant cytoplasm that can be light grey to deeply blue and may show pseudopod formation (Fig 1.04 A.S). Their nuclei are usually round with delicate , lacy chromatin and one or more large prominent nucleoli. . , They are usually strongly positive for n0n- specific esterase(NSE)but have noor only weak myeloperoxidase (MPO) activity, Promonocytes are considered as ' rrooo- blast equivalents" when the requisite per- centage 01 blasts is tallied for the diagnosis of acute monoblastic . acute monocytic and acute myerorronocync leukaemia. Promonoc vtes have a deli- cately convoluted. folded or grooved nucleus with finely dispersed chromatin, a small, indistinct or absent nucleolus, and finely granulated cytoplasm (Fig 1.04 C, 0), Most promonocytes express NSE and are likely to have MPO activity. The distinction between monobrasts and prornonocvte s is often difficult. but because the two cell types are summated ... • 20 Introduction and overview of the classification of the myeloid neoplasms
  • B o F inhibited by NaF, The combination of NSE and the specific esterase, naphthol-ASD- chloroacetate esterase (CAE), which stains primarily cells 01 the neutrophil lineage and mast cells, permits identification of monccvtes and immature and mature neutroph ils simultaneously. Some cells, particularty in myeIornonocytic leukaemias, may exhibit NSE and CAE simultaneously. While normal eosinoph ils lack CAE, it may be expressed by neoplastic eosooohne. CAE can be performed on tissue sections as well as PB ()( marrow aspirate smears. , - ~~ . • • A E c Fig. 1.04 Monoblasts, promonocytes and abnormal mcnccytea from a case of acute monocytic laukaemia. A, B Monoblastsarelarge withabundant cylOlJlasm that maycontain afew vacuoles Of fine granules and have roullCl nuclei withlacy chroma~n and oneOfmore variablyprominent nucleoli. C, DPrornor.ocytes have more irregular ancl delicately folded n~ withfine chroma~n, small indistinct nucleoli and finely granulated cytoplasm. E, FAbnormal monocytes appear immature, yet have more condensed nuclear chromatin, con'o'Q/uledOf fddednuclai, and more cylopIasmiC granulaboo (Courtesyof Or. J.Goasguen). case light grey granules are seen rather than the deeply black granules that char- acterize mverobrasts. The non-specific esterases .u naphthyl butyrate (ANB) and (,( naphthyl acetate (ANA). show diffuse cytoplasmic activity in monoblasts and monocytes. Lymphoblasts may have focal punctate activity with NSE but neutrophils are usually negative. Megakaryoblasts and erythroid blasts may have some mul- titocal. punctate ANA positivity, but it is partially resistant to natrium ffuoride (NaF) inhibition whereas monocyte NSE is totally as rronootasfs in making the diagnosis of AML, the distinction between a monoblast and promonocyte is not aly,.ogys critical. On the other hand, distinguishin g pro- monocvtes from more mature but ab- normalleukaemic monocytes can also be dilficult, but is critical, because the des- ignation 01 a case as acu te monocytic or acute myelomonocytic leukaemia versus chronic myelomonocytic leukaemia olten hinges on this distinclion. Abnormal rrooocvtes havemore clumped chromatin than a promonocyte, variably indented. folded nuclei and grey cytoplasm with rrore abundant lilac-colored granules . Nu- cleoli are usually absent or indi stinct (Ftg 1.04 E.F). Abnormal monocytes are rot considered as monoblast eouvaeots. Megakaryoblasts are usually 01rreoen to large size with a round , indented or irregular nucleus with finefy reticular chromatin and one to three nucleoli. The cytOplasm is basophiliC, usually agranular, and may show cytoplasmic blebs (See Chapter 6 on acute myeloid leukaemia, NOS). Small dysplastic megakaryocytes andmicrornegal<.aryocytes are not blasts. Inacute promyelocytic leukaemia, the blast equivalent is the abnormal promyelocyte. Erythroid precursors (erythroblasts) are rot included in the blast count except in the rare instance of "pure" acute erythroid leukaemia, in which case they are consid- ered as blast equiva lents (See Chapter 6 onacute myeloid leukaemia, NOS). Cytochemistry and other special steins: Cytochemical studies are used to deter- mine the lineage 01 blasts, although in some laboratories they have bee n sup- planted by immun ologic studies using flow cytometry and/or immunohistochem- istry. They are usually performed on PB and8M aspirate smears but some can be performed on sections 01trephine biop - sies or other tissues. Detec tion 01 MPO indicates myeloid d ifferentia tion but its absence does not exclude a myeloid lin- eage because early myeloblasts as well asmonoblasts may lack MPO. The MPO activity in rrweiobtasrs is usually granular and etten concentrated in the Golgi region whereas monobtasts. although usually negative,may show line, scattered MPO+ granules, a pattern that becomes more pronounced in prcmonocvtes. Erythroid blasts, megakaryoblasts and Iymphoblasts are MPO negative. Sudan Black B (SSBl staining parallels MPO but is less spe- etc. Occasional cases of lymphoblastic leult.aemia exhibit SSB POSitiVIty, in which Introduction and overview 01 the ctass.tcanoo 01 the myeloid neoplasms 21
  • In acute erythroid leukaemia. a PAS stain may be helpful in that the cytoplasm of the leukaemic oroervmrobreatemay show large globules of PAS positivity. Well- controlled iron stains should always be per formed on the 8M aspirate to detect iroo stores. normal sideroblasts and ring siderobrasts. the latter of which are de- fined as erythroid precursors with 5 or more granules of iron encircling one-third ormore of the nucleus. Immunophenotype Immunophenotypic analysis using either multiparameter flow cytometry or IHe is an essential tool in the characterization of myeloid neoplasms. Differootiation antigens that appear at various stages of haemato- oo'euc develo pment and in correspon- ding myeloid neoplasms are illustrated in Fig. 1.05. and a thorough descriplion of lineage assignment criteria is provided in the chapters on mixed phenotype acute leukaemia, The techniques employed and the antigens anafyzed may vary accord- ing to the myeloid neoplasm suspected and the information required 10 best char- acterize it as well as by the tissue avail- able. Although often important in the diagnosis ol any haematoiogicaJ neoplasm. immunophenotyping in myeloid neoplasms is most commonly required in AML and in determining the phenotype of blasts at the lime of transfo rmation of MOS. MOS!MPN and MPN, Mulliparameter flow cytometry is the prefer red method of immuno phenotypic analysis in AML due to the ability to ana- lyze high numbers of cells in a relatively short period of time with simultaneous recording of information about severer antigens for each individual cell. Usually. rather extensive panels of monoclonal an- tibodies directed against leukocyte differ- entiation antigens are applied because C U lM- C I)l63+ C IU+ COU+ C O l5-+- COll ++ C DJ .... C OM+ IH...A-OR+ C O l lb++ C O l -t-t "'"CDl6- C D235.- • C U.14- C O.II++ C I)6 I++ C I).&1-+-+ C U"' l+ em s- C lU J '" M''O+ C D65+ C U15+ C D IIII+ C1U 5tlim e m s- m nmx: ylf' toryl hruh l• • 1 c m l 7- ' fh+ C DJ6 - Cll1J~.- C IH Jd lm C IU J + MPO+ C))65+ C D I5+ C U ll b+'_ C DJ4· C DJ8+ C 061+ C 04I+ C04l +I· • C U1I7+ llb-I+ C D.l6- CDIJ ~'- b ....p bllk: torylb rub l.,. C O Il 7+1- C ll1 J+ CD33+ MPO+ C:0 65+ C D I5+/· p rumo"ucy'' ,------''-, r'----, + C IUJ+ CO IS+ C IU J + C D36-+ C I)6"+ HL- -DR+ CO ll b+ C D I4+ mon..hl . ~1 C UJ4+I. C DJ M.,_ C D61+ C I).&I+ ce-e- _ n _ C D3.. + ClHM_ C D IlJ-. C1 U 5 HA - TI'O -R+ C D3.. +-+ 1I1.A.-UR C D.N+-+ Un_ C DJ..... C IH M+ C D U J- C1U5RA+ C U34_ liLA-DR t-tlL -"-LO"--l,. C U.H++ C O}4... C IU + C D U'" ' r"",,::7:-:-~01 C IU 3'"II liLA-DR'" <--U II 7+ lib- C U,J.- C OlJ5.- prvQ')"lbn>bla. 1 22 mtrocucuco and overview of lhe classification of the myeloid neoplasms
  • J the utility of in,s:livid ual markers in identify- ing commitment of leukaemic cells into the different haemat opoietic tlneages is limited Evaluation of expression patterns of several antigens, both membrane and cytoplasmic, is necessary for lineage assignment. to detect mixed phenotype acute leukaemia, and 10 detect aberrant phenotypes allowing lor follow-up of minimal residual d isease . Irrmunopheootypic analysis has a central role in disting uishing between minimally dllferentiated acute myeloid leukaemia and acute lymphoblastic leukaemia, and in CML between myeloid blast phase andlymphoid blast phase. Among AM L WIth recurrent genetic abnormalities, sev- eral have characteristicphenotypes. These patterns. described in the respective sections,can help to plan molecular cvto- genetIC {lluorescence in situ hybrid ization (FISHlI and molecular investigations in individual patients, lm munophenotypic features or the other AMl categor ies are extremely heterogeneous. probably due tohigh genetic diversity. Although it has been suggested that expression of cer- tam antiqens, such as CD?, COO, COl lb, C014. CD56 and CD34 could be associ- ated with an adver se prognosis in AMl, their independent prognostic value is still controversial. Aberrant orunusual omoro- phenotypes have been found in at least 75%of cases of AMl. These can be described as cross-lineage antigen ex- pression, maturational async hronous expression of antigens, antigen overex- pression, and the reduction or abse nce of antigen expressio n, Similar aberrancies have also been reported in MDS as well. and their presencecan be used to support the diagnosis in early or morpholog ically ambiguouscases of MDS (See Chapter 5). lm11unophenotyping by IHC on8 M biopsy sections can be applied if ma rrow cell suspensions are nol available for flow cy- tcmetry analysis. Antibodies reactive with paraffin-embedded BM biopsy tissue are available for many lineage-associated markers (e,g. MPO.lysozyme, CD3, PAX:s, C033, etc.). As noted previously, CD34 staining of the biopsy can fac ilitate the detection of blasts and their distribution , provided the blasts express CD341 1650/. For casesrich in megalob lastoid erythro- blasts. immunohistolog y for glycophorin or haemoglobin may be helpful in dist in- guishing those cells from myeicotasts (eg. in cases of RAEB or acute erythro- 1eI.Memia), and COOl or CD42 oflen aid in the identification of abnormal mega- karvocytes. Genetic studies The WHO classification includes a num- ber of entities defined in part by scecmc genetic abnormalities. including gene rearrangements due 10 chromosomal nansrccarrons and to specific gene muta- tions. so determination of genet ic features of the neoplastic cells must be performed if possible. A complete cytogenetic analy- sis of 8M should be perlormed at the time of initial evaluation to establish the cyto- genetic profile, and at regu lar intervals thereafter to detect evidence of genetic evolution . Additional d iagnostic genetic studies should be guided by the diagnosis suspected on clinica l, morphologic and imTulophenotypi studies. In some cases, reverse transcriptase-polymerase chain reaction (AT-PCR) and/or FISH may de- tect gene rearrangements thai are pres- ent in low frequency and not observed in the initial chromosomal analysis, in cases with var iants of typical cytogenetic abnormalities, and in cases in which the abnormality is cryptic , such as the PDGFRA-FIP1L 1 fusion in myeloid neo- plasms associated with eosinophilia, De- pending on the abnormality, quantitative PCR performed at the time of diagnosis may also provide a baseline against which the response to therapy can be monitored . A number of gene mutations detected by gene sequencing, allele- specific Pe A and other techniques have emerge d as important diagnostic and prognostic markers in all categories of mye loid neoplasms, Mutations of JAK2, MPL, NRAS, NFl, PTPN 11, and KIT in MPN and MDS/MPN, and NPM1, CEBPA, FLT3, RUNX1 and KIT, among others. in AMl are important for d iagnosis and prognosis. and some. particularly JAK2, FLT3, NPM 1 and CE8PA figure impor- tantly in this revised classification. Fur- thermore, the role of gene over- and unde r-expression as well as loss of het- erozygosity and copy number variants detected by array-based approaches are only now being recognized as important abnormalities that may well influence diagnostic and prognostic models in the near future 11531AI. Nevertheless, microarray prof iling studies. although important in the research setting , have not yet been tested in clinical practice. Revised WHO classification of myeloid neoplasms Table 1,0 1 lists the major subgroups of myelold neoplasms and their characteristic features at diagnosis. The nomenclature for the myeloproliferative entities has been changed from "chronic myeloproliferative diseases" to ·myeIoproIiferative neoplasms" and the subgroup formerly designated as "myelod ys pl as ticfmyelo p ro li fe rati ve diseases" has been changed to "myelodysplasticJmyeloproliferative ne0- prasms" to underscore their neoplastic nature. Besides the addition of the new subgroup. "Myeloid and lymphoid ne0- plasms with eosinophilia and abnormalities of PDGFRA, PDGFR8 and FGFRt ,· new entities have been added and/or diag- nostic criteria updated within each sub- group. Myeloproliferative neoplasms (MPN) The MPN (Table 1.02) are clonal haeretc- porenc stem cell disorders Characterized by proliferation of one or more of the myeloid lineages (l.e. granulocytic , ery- throid . megakaryocytic and mast cell). They are primarily neoplasms of ad ults that peak in frequency in the 5th to 7th decade, but some subtypes. particularly CMl and essential thrombocythaemia (ET), are reported in children as well. The incidence of all sub types combined is 6-10/100,000 population annually {1053, 1059. 1060 f, Initially. MPN is cha racterized by hyper- cellularity of the BM with effective naematoporetc maturation and increased numbers of gra nulocytes, red blood ce lls and/o r plate lets in the PB. Splenomegaly and hepatomegaly are common and caused by sequestration of excess blood cells orproliferation of abnormal raemato- poietic cells, Despite an insidious onset each MPN has the potential to undergo a Table 1.02 ~live neoplasms (MPN). ChrtncITl)9logenous1Bukaen'ia, BCR-ABI.posibYe (CMl) Clwtlnic. neutrophilic leubeml8 (CNL) ~'o'efil (PV} """'" _ _ (PM~ ESSoElI'IUl ~ (ET) Oworic eosnophic Ieukaer'ru.NOS lea NOS) "'-MyelqiltMaabYeneoplasm,loI'ldasslJable (UPN,U) introouctco and overview of the ctassrncanon of the myek>id neoplasms 23
  • CML Myeloid neoplasms with eosinophilia PV PMF ET Mastocytosis ABU PDGFRA,PDGFRB,FGFR1 JAK2 V617F, JAK exon 12 JAK2V617F, MPL W15 1UK JAK2V617F, MPL W151 UK KITD816V Fig. ' .06 Myeloprololerative neoplasms (t.4PN)andoIhet myeloid neoplasms associated W11t1 mutaliOnlrearrangementoftyrosine kinase genes. [ j stepwise progression that terminate s in marrow failure due to myelofibrosis, inef- fective haematopoiesis or Iransformalion 10 an acute blast phase. Evidence of ge- netic evolution usually heralds disease progression as may increasing organa- megaly, increasing or decreasing blood counts, myelofi brosis and onset 01myelo- dysplasia. The finding of 10-19% blasts in the P8 Of 8M generally signifies accel- erated disease and 20% or more is suHicient for a diagnosis 01blast phase. Rationale for tho diagnosis and classification of MPN In previous classification schemes the detection of the Philadelphi a chromo- some and/or BCR-ABL1fusion gene was used to coolirm the diagnosis of CMl whereas the remaining MPN subtypes were diagnosed by their clinical and labo ratory features with relatively minor contributions to the diagnosis from mor- phologic findings. A number of criteria were required not only to distinguish subtypes of MPN from each other but from reactive granulocytic. erythroid andl or megakaryocytic hyperplasia. Revisions in the criteria for cla ssification of MPN in the current scheme have been influenced by two factors - the recent discovery of genetic abnormalities in- volved in the pathogenesis of BCR-ABL1 negative MPN and the wider appreciation that histologic features (megakaryocytic morphology and topograph y, marrow stromal changes, identification 01specific cell lineages involved in the proliferation) correlate with clinical features and can be used as criteria to identi fy MPN subtypes {2177. 2216, 22221. Most if not all MPN are associated with clona l abnormalities involving genes that encode cytoplasmic or receptor PTKs. The abnormalities described to da te include transiccanons Of point mutations of genes that result in abnormal, constitu- tively abnormal PTKs that activate signal transducti on pathways leading to the abnormal proliferation. In some cases, these genetic abnormalities. such as the BCR-ABL1fusion gene in CMl . areesso- cia ted with consistent clinical, laboratcry and morphologic findings that allow them to be utilized as major criteria for classfi- cation, whereas others provide proof that the myeloid prolifera tion is neoplastic rather than reactive. Acquired somat ic mutations of JAK2. at chromosome 9p24. have been shown);) playa pivotal role in the pathogenesisd many cases of BCR-ABL 1negative MPH 11044, 1163, 1186, 1287A, 12881. The most common mutation, JAK2 V617F, re- sults in a constitutively active cytoplasmic JAK2 that activates signal transducer and activator of transcription (STAT), mitogen activated protein kinase (MAPK) and phospholidyllnositol a-kmase(P13K) sigo naling pathways to prorote transforma1Ol and proliferation of baemaroooenc pro. genitors (Fig. 1.07). The JAK2V617Fmu- tation is found In almost all patients wit~ polycythaemia vera (PV) and in near~ one-half of those with primary myelofil:Jrosis 24 Introdu::tion and overview of the classi fication of the myeloid neoplasms
  • Activation of gene!o Important in proliferation andsurvival their relevan ce are in progress and revi- sions may be necessary. Myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1 Determi ning the cause of marked , per- sistent eosinophilia (~ 1 .5x1()9/l) in the blood can be challengi ng and is some- times cli nically urgent because 01 the potential damage to the heart, lungs , cen- tral nervous and other organ systems caused by the eosinophilic infiltration and release of cvtocnes. enzymes and other proteins. The eoeoooous may be derived from the neoplastic clone of a myeloid neoplasm, such as GEL, GMl orAMl, or lhey may be reactive due to abnormal ~ I (0 I E0 I ~0 I @jJ -- ------- IX B I Akt ¥ ""'-.,TO FoxO A and abnormalities 01 PDGFRA. PDGFRBor FGFR1 , If none of these rearrangements are detected, and there is no BCR-ABL 7 fusion gene, they should be categorized as GEL, not otherwise specified 4. The diagnostic algorithms for PV, ET and PMF ha ve been substantially changed to incl ude information regarding JAK2 and similar activating mutations as well as pertinent histolog ic features 01the 8M biopsy as diag nostic Criteria. 5. The threshold of the platelet count for the diagnosis of ET has been lowered to ~45Ox 1 Q91l. 6. Criteria for CMl in accelerated phase have been suggested with the caveat that they have not been fully evaluated in the era of PTKI therapy: studies 10 determine Fig. 1.07 MecRanism oractivatiOn aIJA1<2 kinaseactMtyby rn.rtaIiOns in the JAK2 Signalirg pathway. It.Cytokile ligalldsnormaHy bind cytokine recepIors, .tlich resultsinJaI'llS kiase 2 (JAK2) pIlosphoryIatio, recruilmenI rcInsduc:er and actrvator allJansaipbon (Stal) signaling protelns and pIlospholyIation alld activatiOn ofdownstream SigRaIing pathways ind.I:lIng SIal ~ lactor&,lTIlogefIlIdMlled proIeIn U1ase(MAPK) sigMWlg proteins , arIl the phosphotidyinos 3-kinase (Pl3K)--Akt pathway B The JAK2 Vfi17F alld JAK2 ewn 121Tl11anl kilases bind cytokine recepIors, are phosphorylated il the absence alligand and lead to~ activation aI0JwIn. streamsignaing palhways. C Bycontrast, MPl. W515lA(rrUal'lllhiOi'~ recepb$ are able 10 phospI1Oi'yale ri1-Iype JAK2lithe absence 01 hanbopoleIi., and red IItle aetwabon ofsignaling paltrways <townstream01IN<2. Negativeregulation 01 JAX2 sigNIng is nonnaIy medIaIed bysuwessorofcytome s9laIilg (Socs) proWls, most notably SOCSl alld SOCS3; recent dala i'ldic3IeIhalthe JAK2 V617F aIeIe night escape negatiYe IeectIacll by SOCS3. Repro:U;:ed from {1287AI Stmnary 01major changes in the classilication of MPN I. The nomenclature , 'mveiopronteranve disease" has been changed to "myelo- proliferative neoplasm" 2, Mastocytosishas been included in the MPN category 3 Some cases previously meeting the Cfllena forchronic eosinophilic leukaemia (CEllmay now be categorized as myeloid (J ~d neoplasms with eosinophilia (PfvlF) and wit~ esseotelmoroocvmaeraa (ET), In the few PV patients wnolack the JAK2 V617F, an acti vating JAK2exon 12 mutation may be found , and in a small proportion of cas es of PMF and ET, an ac- tivating mutation 01 MPL W515l or W5 15K is seen. It is important 10 note that JAK2 V617F is not specific for any MPN nor does its absence exd ude MPN . Further- more, it has been reported in some cases of MDS/MPN, in rare cases of AMl, and incombination with other well-defined ge- netic abnormalities such as the BCR-A8L 7 110641. Thus, diagnostic algorittvns for PIl, ET and PMF have been altered to take the mutationalstatus of JAK2 into account as weN as 10outline the additional laboratory and histo6ogic "ndi~JS required to reach anaccurate classification 01 cases, re- gardless 01 whether the mutation is or is notpresent. In addition to the changes in the criteria lorN, ET and PMF, information reg arding abnormal PTK toncnon due to rearrange- mentsofthe POGFRA, PDGFRBor FGFR1 genes in patients with myeloid neoplasms associated with eosinophilia led to reap- praisaland new diag'1ostiCalgorithms for thosesyndromes as well (see below). The appreciation01the role altered PTKs play in the pathogenesis of CMl, PV, ET and PMFalso argues lor the inclusion of simi- lar chronic myeloid pronteranons related 10 PTK abnormalities under the MPN um- brella.Thus,systemic mastocytosis, which hasmany features in common with other MPN entities and is almost always asso- ciated with D816V mutation in the KIT geneencoding the recep tor PTK, KIT, has beenadded to this category 121761 Still, tI"1e molecular pathogenesis of nearly half of all cases of ET and PMF, of all cases of chronic neutrophilic leukaemia and a mm berof myeloid neoplasms associated with eosinophilia remai n unkn own. For thesereliance on clinical, laboratory and morphologic features is essenti al for diagnosis and classification, Introduction and overview of the classification 01 the myeloid neoplasms 25
  • cytoki ne release from reactive or neo- plastic r-ceus. In a number of cases. no underlying cause can be fOund and the clonahty of the eosinophils cannot be proven: these cases are app ropriately termed "idiopathic hypereosinophilic ssn- drome" (See Chapters 2 and 3). Rationale for diagnosis and classification of myeloid and lymphoid disorders with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR, Since the last edition of the WHO classifi- cation it has been recognized that many cases of eosinophilia, including a sub- stantial number considered as "idiopathic" are clonal myeloid neoplasms caused by abnormalities in genes that encode the alpha or beta chains 01 the receptor PTKs, platelet derived growth factor receptor (PDGFR) or fibroblast growth factor reo ceptor 1 (FGFR1), Rearrangements 01 PDGFRB at chromosome band 5q33 that lead to constitutive activation of the beta moiety of PDGFA were first recogni zed in cases variably reported as CEL or chronic myelomonocytic leukaemia (CMML) with eosinophilia 1131, 812. 20851. More re- cently the gene that encodes the alpha moiety of the PDGFR, PDG FRA, at chro- mosome band 4q12. was found to be involved in cryptic translocat ions in CEl and in nearty one-half of cases reported as idiopathic hypereosinophilic syndrome 14661· In addition, rearrangements of the FGFR 1 tyrosine kinase gene have also been implicated in myeiooronteratrons with prominent eosinophilia 13, 13541. However, the clinical and morphologic presentations associat ed with FGFR 1 rearrangement are variable, and include not only presentation as a myeloprolifera- tive neop lasm with eosinophilia, bul also as AML and they may even present as, or evolve to. precursor T or B lymphoblastic leukaemia/lymphoma with prominent eo- sinophits Cases associated with PDGFRA rearrangements can likewise present as AMl or precursor t-een neoplasms 114691. Tlb.. 1.03 Myeloid and lymphoid neoplasms W11t1 eosmphi liaard abnormal~m ol POOFRA,POOFRB,or FGFR1. Myeloid and lymphoid neoplasms with PDGFRA real1"angement Myeloid nooplasms withPDGFRB rearrangemeot Myeloid aooIylTVIOid neoplasms wiltl FGFRf abnormallbes Although it might seem most efficient to categorize these cases as CEl within MPN, this would ignOfe cases WIth PDGFRB abnormalities that present as CMML as well as cases of FGFR1 and PDGFRA rearrangements that may even have a lymphoid conoooenr. To accom- modate Ihese transiccatons. a new sub- group defined largely by the genetic abnormalities of PDGFRA, PDGFRB or FGFR1 has been added (Table 1.03). Detection of one of these abnormalities places the case in this category, regard- less at the morpholog ic classification. Cases of myeloid neoplasms with eosinophilia that lack all of these abnor- malities and that meet the criteria for CEL. NOS, in the MPN catecov should be placed in that group. Myelodysplastic/myeloproliferative neoplasms (MDSlMPN) The MDS/MPN (Table 1.04) include clonal myeloid neoplasms that at the time of ini- tial presentation have some clinical, labo- ratory or morphologic findings that support a diagnosis of MDS, and other findings more consistent with MPN They are usually characterized by bvpercenu- larity of the BM due to proliferation in one or more of the myeloid lineages. Fre- quently, the proliferation is effective in some lineages with increased numbers of circulating cells that may be morphologi- cally and/or func tionally dysplastic. Si- multaneously, one or more 01 the other lineages may exhibit ineffective prolifera- tion so that cytopenlate) may be present as well. The blast percentage in the BM and blood is always <20%, Although hepatosplenomegaly is common, the clin- ical and laboratory findings vary and lie along a continuum between those usually associ ated with MDS or those usually associated with MPN Patients with a well- defined MPN who develop dysplasia and ineffective haematopoiesis as part of the natural history of their disease or after chemotherapy should not be placed in this category. Rarely, some patients may present in a transformed stage of an MPN entity in which the chronic phase was not recognized, and may have findings that suggest that they belong to the MDS/MPN group. In such cases, if clinical and labo- ratory stud ies fail to reveal the nature of the underlying process, the designation of MDS/MPN, unclassifiable may be ap· orcorare.Paneotswro havethe BCR·ABL 1 fusion gene or rearrangementsof PfX3FRA TableU4 ~neopIasms (MDSlMPN). cmnc myelomonocyllc leukaenU (CMMl) Atypocal chrooiC myeloid leukae~ , BCR-ABLI negative (aCMl) JIMIrIiIe myelomooocytic leukaemia (""'Ml) MyekldysplastcIMyeloproliferative neoplasm, undassdiable (MDSlMPN ,U) Provisional entity: Refractory anaemia wittlMrlg sideroblasts and ltJramt>ocytasis (RARS-n should not be categorized as MDS/MPN. and in contrast to the criteria used in the 3rd edition of the WHO classification, cases of CMML with PDGFRB rearrange- ments are also excluded Rationale for diagnosis and classification of MDSlMPN This diagnostic category was introduced in the 3rd edition amidst controversy as to wl1ether some entities, particularly CMML, would be better categorized as either MDS or MPN depending on the extent of myeloprol iferation as evidenced by the WBC count. Some cases of CMML have low neutrophil counts and only modestly elevated monocyte counts and resemble MDS clinically and morphologically whereas others have markedly elevated WBC counts and organomegaly more in keeping with MPN. yet criteria that clearly distinguish biologiCally relevant subtypes of CMML remain to be defined . To date, a lew cases of CMML and atypi- cal chronic myeloid leukaemia, BCR-ABL1 negative (aCML) have been reported to demonstrate JAK2mutations that charac- terize BCR-ABL 1 negative MPN, but the prol iferative aspec ts of most cases of MPD/MPN are related to aberrancies in the AAS/MAPK signaling pathways. In ju- venile myelQmonocyticleukaemia (JMML) nearly 80% of patients demonstrate mutually exclusive mutations 01 PTNPN1', NRAS or KRAS, or NFl 11329. 2096, 21621. all of wl1ichencode signaling pro- teins in AAS dependent pathways, and approximately 30- 40% of cases of CMML and aCML exhibit NRAS mutations {1686, 2311, 24171. In view of the lack of any specific genetic abnormality 10 suggest that these entities should be relocated 10 another myeloid subgroup, they remainin this "mixed" category which acknowledges the overlap that may occur between MDS and MPN.Casesof CMML with eosinophilia associated with PfX3FRB rearrangements are excluded , but rare cases of CMML nurooocuoo and overview 01 the classification of the myeloid neoplasms
  • witheosinophilia that do not exhibit such rearrangements should be cJassified in thiscategOry Themost controverstat issue in the sub- groupatMDSIMPN is the provisional entity. refractory anaemia with ring sideroblasts andthrombocytosis (RAR5-T). The major- ity(SO- 60%) 01 cases of RARS-T studied lor JAK2V617F carry this mutation 1234. 354.762 , 1835. 1839. 1969,2081,2139. 23581. This has prompted the notion that RARS-T should be moved to the MPN group of myeloid neoplasms. whereas othershave argued thaI RARS-Tis not an entity at all but merely one of the better recogniZed MPN entities, such as PMF or ET. i'l which genetic evolution has led to a dysplasticteanse. ring sideroblasls 11966. 2139. 23581. In a few cases reported. hl:1Never.the cells of patients with RARS-T. when studied by in vitro cul ture tech- niques, have growth characteristic more in keeping with MOS than MPN 1234, 18351. An additional question is hOw to clearlydistinguish RAR5-T from RARS, in which moderately elevated pla telet counts are etten reported . This question ismorepressing in view of the revised cri- teria for RARS-T that lowers the platelet threshold from ~x lrJl/L to ~450x 1rPlL, in parallel with the revised threshold lor Ef It is important to note that the diag- nostic criteria for RARS-T include not only theIinding of an elevated platelet coun t in conjunction with anaemia and ring elder- oblasts in the 8M, but also morphologi- callyabnormal megakaryoc ytes similar to thoseof ET or PMF. Only a few patient s with RARS and plate let counts in the 450,500x W9/L range have been studi ed for JAK2 mutations and in most with plateletcounts in the lower rang es no mu- tations have been found . Neverth eless, more studies are need ed , and we recom- mend to test for JAK2 mutations in pa- tents whohave RARS and platelet counts above the normal range. The sum of cur- rent informationregarding RAR5-T argues for its continued placement in the MDS/MPN category. but in view of the debate regarding its precise definition and nature, it is best regarded as a 'provisional entity" until more data are available, lastly. classification of myeloid neoplasms that carry an isolated isochromosome t 7q andthat have less than 20% blasts in the P8or BM may prove difficult. Some au- thOrs suggesl this cytogenetic defect defines a unique disorder characterized by mixed MOS and MPN features associ- ated with prominent pseuoo-Percer-Hoet anomaly of me neutroot urs. low 8M blast count, and a rapidly progressive clinical course. Most cases reported have a prominent monocytic component and meet the criteria lor CMML, but in some, the PB monocyte coun t may not reach the lower threshold for that dia gnosis 1708, 14371· In cases that do not fu"ill the criteria lor CMML or another well defined myeloid category. designation as MOSIMPN. un- classifiable. with isolated isochromosome 17q abnormality, is most appropriate. $urTmary of major changes in MDSIMPN 1. Some cases of CMML with eosinophilia are relocated to the category, "Myeloid neoplasms with PDGFRB rearrangement" 2. The category, "Atypical CML" has been renamed as •Atypical CML. BCR-ABL 1 negative" to emphasize this disease is not merely a variant of BCR-ABL 1 positive CML. 3. RAR$-T remains as a provisional enlity, classified as MDS/MPN . uncrassiuabre. until further data clarifies its appropriate designation. The criteria for its recognition have been modified. The platelet thresh- old has been lowered to ~45Ox 1rPll, and megakaryocytes with morphology similar to those seen in ETor PMF must be present Myeladysplastic syndromes (MOS) These disorders, usually characterized by the simultaneous proliferation and apop- tests of baematopoienc cells that lead to a normal or nvoerceuurar BM biop sy and PB cytopenia(s), remain among the most challenging of the myeloid neoplasms for prope r diagnosis and classification , The general features of MOS, as well as specific gu ide lines for diagnosis and classification are outlined in Chapter 5. An impo rtant addition to the MOS cate- go ry (Table 1.05) is the provisional entity, refractory cytopenia of childhood (RCG), This category is reserved for children with MOS who have <2% blasts in their PB and <5% in their 8M and persistent cvtope- nia(s) with dysp lasia, In contrast to MDS with refractory cvtcoentee in eoutts. the majority of cases of ACC have hypocellular 8M biopsy specimens, and the distinction from acquired aplastic anaemia and inherited BM failure syndromes is often challenging 117841, An issue appropriate 10 menton at this point is the cntene used for ctassmcatco of myeloid neoplasms in which more lhan 50% of the BM cells are erythroid precut- sors. and for which acute erythroid leukaemia is considered a possible diag- nosis. In such cases. if blasts account for fewer than 20% of WBC in the PB and 01 all nucleated 8 M cells, and for less than 20% of the non-erythroid cells in the BM (lymphocytes, plasma cells, etc. are also excluded in this latter calculation), the case is considered as MOS. In this sce- nario. there is lack of consensus among members of the WHO committee as to whether the MOS should then be classi- fied according to !he blast perceotace of all nucleated 8 M cells or according 10the blast percentage of all non-erythroid BM cells. but the majority recommends that the MOS be classified using the blast per- centage of all marrow nucleated cells. Many cases of refractory anaemia with ring sioerobrests as well as refractory anaemia have marked erythroid prolifera- tionand using the blast percentage of the non-erythroid cells lor classification of such cases might cause these to be placed in an unnecessarily high-risk cat- egory. On the other hand , if there is severe multilineage dysplasia, very bizarre erythroid morphology. and/or minimal or no maturation to segmented neutroobus. and the btast percentage of total 8M cells is not sufficienl to place the case into a high-g rade MOS category, the case shoul d be flagged tor clinical correlation and discussion, with careful follow-up (Tab le 1.06). More studies are needed however to cla rify this controversial issue. Acute myeloid leukaemia (AML) AML is a disease resulting from the clonal expansion of myeloid blasts in the PB, 8M , or other tissue, It is a heterogeneous disease clinically, morphologically and ge netically and may involve only one or Tabl. 1.05 Myelodysplastcsyndromes, Reffacto!y ~nia wlltlll1 iWleage dysfllas48 (RCUD) Reffa<:byanaemia (RA) Refracloty neutropenia (RN) Refradcry ltuQmbocytopenia (RT) Re!fadclry allaemia with ri1gSiderObIasts (RARS) Relractory cytlpenia with ITIJlblineage dysplasia (RCMD) Refractory all8e/l'M8 wiII1 excess bIasls (ME B) MyelodyspIa$llc syncWmewilI1 iSOIatecI dfll(Sq) Myelodysplllsbc syndrcIme. undas.sJliable (J.I>S.U) C*hood ~ syrw:lrome Pn:MsicnaInty Refra:t:ry ~ ~ d*hlod (ROC) Introduction and overview of me classification 01 the myelOId neoplasms 27
  • Table1.06 PMSib1e d~ when erythroid precursors ~50'10 ofbone marrow nucleatedcells. %Erythroid ~ Blocdhnarrowfindirlgl. 0ltIer f1odlng& DIagnosis ......- • Erythroid precursors, lymphoid cellsandplasmacens aresubtracledfroma" nlJdeatedmarrowcells to calDJlate the"noo-erythroid eels"inthebone marrow. - ~ blasts inblood or Case meets alterialor AML With fl'lyelodyspIaSia ofallnucleatedmarrow AMLwith my8lOdysplasia· related changes - related changes ~ inmatln IJyIIwid Few • lit'{ myeIclt:Qsts Miwnall <Wly PIn 8I)tWIlid IeWemia """""...,"""'" """""'"matlJflllJon _01 >5011 -_.- fIm.>MiKi1I -,--blasts <m d II ~celsll ....... """"""""""- .." """"" '50' <20% blastsinblood, Blasts<20% 01 all MDS: classifyMDS blasts <20% ofall ~roid' cells in acx:oroing 10 number of """'"'"""""- ...""""" blasts inbloodandblasts as pen:entIge d II """""""""""- pathways to promote proliferation/survival A similar multistep process is also evident in AMl that evolves from MDS orthat has myelodyspl asia-related features, often characterized by loss of genetic material and haploinsufliciency of genes. Within the last few years, genetic mutations have also been identilied in cytogenetically normal AML 115321. Sane of therrutations, such as those of CEBPA and perhaps NPM1invdve transcriplion faclors. whereas erne-e. including those of FlT.J and NRASIKRAS. affect signal transduction. Not only have these mutations led to an unde rstand ing of leukaemocenests in cytogenetically normal AML, bul they have proved to be powerful prognostic factors 115321. In summary, genetic ab- normalities in AML elucidate the patho- genesis of the neoplasm, provide the most reliable prognoslic information, and will likely lead 10 development of more successful targeled therapy. One of the challenges in this revision has been how to incorporate important and/or recently acquired genetic information into a classification scheme of AMl and yel adhere to tile WHO principle of defining horoogeneOuS, biologically relevant entities based not only on genetic studies or their prognostic value, but also on clinical, morphologic and/or immunophenotypic studies . This was particularly problematic for the most frequent and prognostically impo rtant mutat ions in cytogenetically normal AML, mutated FLT3, NPM 1 and CEBPA. They have few or variably con- sistent morphologic, irrwnunophenotypic and clinical features reported to dale , and the mutation s are not mutually exclusive. For the most par t, the framework coo- structec in the 3rd edition proved flexible enough to incorporate the new entities proposed by members of the WHO c0m- rmtteeand the CAC (Table 107). The en- tities initially described in the subgroup ·AML with recurring genetic abnormal- nee' remain with only minor modifications (Table 1.07) and three more entities, char- acterized by chromosomal transtocatioos associated with fairly unilorm morpholog- ical and clinical features have been added. Cases with mutated NPMl and CEBPA are added to the same subgroup as ' provisional entities' indicating that more study is needed 10 lully characterize and estab lish them as unique entities Although mutated FLT3is not included as a separate entity because it is found to be associated with a number of other entities, maturation, the diagnosis does not nec- essarily translate into a mandate to treat the patient for AML; clinical factors. in- cluding the pace of prog ression of the disease, most atways be taken into con- sloerenon when deciding therapy. Rationale for the WHO diagnosis and classification of AML The 3rd edition 01the WHO ctassrncatoo ushered in the era of formal incorporation of genetic abnormalities in the diagnostic algorithms for the diagnosis of AML. The abnormalities included were mainly chro- mosomal transiocenoee involVing tran- scription factors and associated with charac teristic clinical, morphologic and immunophenotypic features Ihat formed a ·clinico-pathologic-genelic· entity. As knowledge regarding leukaemogenesis has increased, so has the acceptance that the genetic abnormal ities leading to leukaemia are not only heterogeneous, but complex, and multiple aberrations often cooperate in a multistep process to initiate the comple te leukaemia pheno- type. Experimental evidence suggests mat in many cases, although rearrange- ment of genes such as RUNX1, CBFB or RARA that encode transcncuon factors impair myeloid differentiation, a second genetic abnormality is necessary to pro- mote proliferation or survival of the neo- plastic clone (Fig. 1.08) 11135AI. Often. the additional abnormalities are mutations 01genes such as FLT30r KITthat encode proteins that activate signal transduction all myeloid lineages. Worldwide the inci- dence is app roximately 2.5-3 cases per 100,000 popu lation per year, and is reportedly highest in Australia. Western Europe and the United States. The me- dian age at diagnosis is 65 years, with a slight male predominance in most coun- tries. In Children less than 15 years of age, AML com prises 15- 20% of all cases of acute leukaemia, with a peak incidence in the first 3-4 years of lite 1559A, 2463AI. The requisite blast perce ntage for a diag· rosrs of AML is 20% or more mveiobtasts and/or monoblastslpromonocytes and/or megakaryoblasts in the P8 or BM. The di - agnosis of myeloid sarcoma is synony- mous with AML regardless of the number of blasts in the PB or BM, unless the patient has a prior history of MPN or MDS/MPN, in which case myeloid sarcoma is evidence of acute transforma- tion. The diagnosis of AML can also be made when the blast percentage in the PB and/or BM is less than 20% if there is an associated t(8;21XQ22;Q22), inv(16)(p13.1Q22), t(16:16XP13.1;Q22) or t(15;17)(Q22:q 12) chromosomal abnor- mality, and in some cases of acute ery- throid IeuI<aemia when eryttvoid precursors account for more than SO% of the BM cells and blasts account for more than 20% of the non-erythroid marrow cells (See Chapter on acute myeloid leukaemia, NOS). Although the diagnosis of AML using the above guidelines is operationally useful to indicate an underlying defec t in myeloid 28 IntroductIOn and overvIew of the ctassuceuoo of the myeloid neoplasms
  • to their genetic abnormalities, but until more data are available, we recommend thai such cases be classified as AML with myelodysplasia-related changes (multilin- eage dysplasia) with the mutational status of the gene appended, Therapy-related myeloid neoplasms (t-AMLJ t·MDS and t-AMlIt-MDSlMPN) remain in the revised classification as a distinct subgroup. However, most patients who develop therapy-related neoplasms have received therapy with both alkylating agents as well as with topoisomerase II inhibitors, so that a division according to the type of therapy is usually not practical and not recommended in this revision. It has been argued that 90% or more 01 cases with I-AMLIt-MDS or t-AMl/t-MDSI MPN have cytogenetic abnormalities similar to those seen in AML with recur- rent genetic abnormalities or AML with myelodyspiasia-relaled features and could be assigned to those categories. However, except for patients with t-AML who have inv(16Xp 13.1q22), t(16;16XP13.1;q22)or t(15 :17Xq22;q 12), in most reported series those with therapy-related myeloid neo- plasms have a significantly worse clinical outcome Ihan their de novo counterparts with the same genetic abnormalities 136, Impaired haematopoietic differentiation and .ub- HqUent .poptos~ PML-RARA RUNX1-RUNX1Tl CBFB-MYH11 MLL fusions CEBPA NPM11 Class II mutations Atutt myeloidIeukaemi,with recurrent gtllllIlIt Ibnormalitles AMLwith~8;2 1 )(Q22:Q22): RUNXt-RUNXm AML withinv{16)(p13.1q22}c.(16:16Kpl3.1:q22); CBFB-MYHIt APl with (15;17)(q22:Q12); PML-RARA AMLwitht(9:11){p22:q23}: MLLT3-MLL AMl witht(6:9)(p23;Q34): OEK-NUP214 AMl withinv(3KQ21Q26.2) ort(3:3J(Q21;q26,2); RPN1·EVll AML(megakeryoblastic)with 1(1;22)(p13;q13): RBMI5-MKL 1 Provisional entity:AMl with mutatedNPM1 Provisional entity:AMLwith mutatedCEBPA Acutemyeloid leukaemia with mye!ody,plilil-related changes Therapy-related myeloid neoplil5m, Acutemyeloid leukaemia, no! otherwl$l spec;lrted AMLwith minimal diffe!lll1tialiorl AML without maturation AMLwithmallJ"aUon Acute m~ leukaemia Acute roonoblasticJmooocytic Ieukaemla Acute ~ IeukaelBas PIseerythroid leukaemia EIythroleukaemia, 8I')1hroidfmyeloid Acute megakaryoblas.lic Ieukaetnia Acute basophl1ic Ieukaen'Ha Acute panmyeIosis withmyebfibrosis Myeloidsarcoma Myeloidproliferations related to Down syndrome Transaent abnormal myelopoiesis Myeloid leukaemia ISSOCiaIed withDown syndrome Blastic plil5maC}'loid dendritic u1llll1oplalms Table 1.07 Acutemyeloid leukaemia andrelatedmyeloidneoplasms, should be evaluated for FLT3, NPMI and CEBPA rnutanons. Currently, however, the clinical significance of a mutalion of one or more of these genes in the setting of morphologic multilineage dysplasia is not clear. Future studies may well prove that such cases are better classified according FLT3-ITD FLT3-TKO KIT RAS PTPN11 JAK2 Class I mutations Proliferation and/or survival advantage; not affecting differentiation its siqrsbcance should not be uoderest- mated, and it is essential that it be tested for in all cytogenetically normal patients, including those who demonstrate NPM1 and CEBPA mutations. Modifications have been made in the subgroup previously ter med "AML with multilineage ovsprasta." Initially, it was envisioned that this group would encom- pass biologically unique AML charac ter- ized by MD$-like fea tures, incl ud ing unfavourable cytogenetics, a higher lnc t- oence of ove rexpressfon 01 multidrug resistance gfycoprotein (AS CS1or MDR-1) andan unfavou rable response to therapy. Dysplasia in ~50% of ce lls in two or more heematopoienc lineages was used as a universally-applicable surrogate marker for the myelodysplasia- relate d featu res. Although the clinical significance of this grOl.lp has been verified in some stud ies , it has been disputed in othe rs in which multivariate analysis showed that multilin- eage dyspla sia had no independent sig- nificance in predi c ting clinical outcome wen cytogenetic findings were mcorpo- rated in tne analysis 169, 869, 2356, 24651. Accordingly, in this revision, this group has been renamed as "AML with myelodysplasia- related changes," Pa- tientsmay be assigned 10this category if theyevolve Irom previously documented MOS. have specific myelodysplasia- relatedcytogenetic abnormalities. or lastly, if they exhibit morphologic mu ltilineage dysplasia as def ined above. Patients in Ianer group with a normal karyotype Introduction and overview of lhe classification 01the myeloid neoplasms 29
  • 227, 1886~ 2034 , 204 1}, suggesting some biological differences between the two groups. Furthermore, the study of ther- apy-related neoplasms may provide valu- able insight into the pat hogenesis of de novo disease by provid ing clues as to why a few patients develop leukaemia whereas most patients treated with the same therapy do not. Therefore, patients with therapy-related neoplasms should be designated as such, but the specific cy- togenetic abnormality should also be listed, for example, "therapy-related AML with «s,11}(p22;q23)". Acute myeloid leukaemia, not otherwise specified, encompasses those cases that do not fulfil the specific criteria of any of the other entities. This group accounts for only 25-30% of all AML that are not as- signed to one of the more specific cate- gories. As more genetic subgroups are iden tified , the number of patients that fall into the AMl , NOS categories will can- tmoe to diminish. Of note is that informa- tion used to characterize the subgroups within this category, such as epidemic-- logic or clinical outcome, is often based on older stud ies that included patients now assigned to d ifferent diagnostic cat- egories. and may not be reliable. Al- though the proposal to collapse this category into fewer subgroups has been made. the notion that some of these may yet be found to be associated with spe- cific genetic or biologic abnormalities argued to maintain this category. Myeloid sarcoma, an extramedullary tumour mass consisting of myeloid blasts, is included in the classification as a dis- tinct pathologic entity. However, when myeloid sarcoma occurs de novo, the diagnosis is eq uivalent to a diagnosis of AML. and further evaluation, including genetic analysis, is necessary to deter- mine the appropriate classification of the leukaemia 117421. When the PB and BM is concurrently involved by AMl. mese tis- sues may be used for analysis and further classification. However, when the myeloid sarcoma precedes evidence of PB or BM invotvement. the irrvnunophenotype should be ascertained by flow cytometry and/or irrvnunohistochemistry, and the genotype determined by cytogenetic analysis, orin the absence of fresh nssue. by FISH or molecular ana lysis for recurrent genetic abnormalities. Myeloid sarcoma may also be the initial indication 01 relapse in a patient previously diagnosed With AML or may indicate disease progression to a blast phase in patients with a prior diag- nosis of MDS, MDS/MPN or MPN. Lastly, the unique features of Down syn- drome- related myeloid neoplasms has been recognized in a separate listing that includes transient abnormal myelopoiesis and myeloid leukaemias (MDS/A ML) associated with Down synd rome. Summary of major changes In AML 1. AML with recurrent genetic abnormalities, a) AML with t(8;2 1)(q22;q22), AMl with inv( 16}(p 13.1q22) or I( 16;16}(p 13.1;q22), and APL with t(15;17}(q22;q 12) are con- sidered as AML regardless of blast count; for all others, blasts 2:20% of P8 or of all nucleated BM cells are required. b) In API... with1(15;17)(Q22;q12); FM..-R.AR4, variant RARA uenslocaucos with other partner genes are recognized separately; not all have typica l APl features and some have ATRA resistance. c ) The termer category, AML with 11q23 (MLL) abnormalities has been re-defined as -AML with 1(9;11)(p22;q23); MLLT3-MLL". Balanced transtocanons other than that involving MLLT3 should be specified in the diagn osis. Other abnormalities of MLL, such as partial tandem duplication of MLL should not be placed in this category. d) Three new cytogenetically delined enti- ties are added : AML with t(6;9)(p23;q23); DEK-NUP214, AML with inv(3)(q21q26.2) or t(3;3)(q21 ;q26.2); RPN1-EV/1; and AMl (megakaryoblaslic) with t(1;22)(p 13;q 13); RBM15-MKL t. e) Two provisiona l ent ities are added: AML with mutated NPM1 and AMl with mutated CEBPA. Although not included as a distinct entity, examination lor muta- tions of FLT3 is slrongly recorrwnended in all cytogenetically normal AML. 2. AM L with myelodysplasia-related changes . a) Name changed from ·AML with rrulli- lineage dysplasia". b) Cases of AML are assigned to this cat- egory if 1) they have a previous history of MDS and have evolved to AML, 2) they have a myelodysplasia-related cytoge- netic abnormality, or 3) if ;<:50% 01cells in two or more myeloid lineages are dys- plastic , 3. Therapy -related myeloid neoplasms. Cases are no longer subcategorized as "alkylating agent related" or ' tccoiso- merase tl-intubttor related" or "other", 4. AML, NOS. a) Some cases previously assigned to the subcategory of AMl. NOS as acute ery- throid leukaemia may be re-classihed as AML with myelodysplasia-related changeS. b) Cases previously categorized as AML NOS. acute megakaryoblastic leukaemia should be placed in the appropriate ge netic category il they are associated Withinv(3)(q2 1q26.2) or t(3:3)(q21;q26.2); RPN1-EVlf, or AML (megakaryoblastic) with t(1;22)(p 13;q 13); RBM15-MKL 1.1JcM'n syndrome related cases are excluded from this category as well. 5. Myeloid proliferations related to Down syndrome. New category to incorporate trans ient abno rmal myelopoies is as well as myeloid leukaemia that is Down synd rome related MDS related to Down syndrome is con- sidered biolog ically identical to AML related to Down syndrome. 30 Introduction and overview of the classification of the myeloid neoplasms
  • , , . /~ •
  • Chronic myelogenous leukaemia, BCR-ABL1 positive J W _Vardiman J ,V. Melo M. Baccarani J. Thiele Synonyms Chronic granulocytic leukaemia; chronic myeloid leukaemia Etiology Factors predisposing to CML are unknown. Radiation exposure has been implicated in some cases 1226, 4791. There does not appear to be an inherited disposition. Clinical features Most patients are diagnosed in CP which usually has an insidious onset. Nearly 20-40% of patients are asymptomatic and are diagnosed when a white blood cell F""i-2.o1 CML. ctvoricphase. A ~ blood SlTlllit" showing Ieukocy1osis and neu1rophiIic eels at varyI1g stagesd malnIKn 8asqJIiIia is~ ttl dyspIasiI iii ~ B Bone marrowbiopsy$I'lOw$markedhypeI- c:eIIuIanty due to granulocytic prolderabon. C The megaka/yOC)1es in CMlare c:harac:leilsbcaly ~ ItIan ~ megakaryocyIes. for less than 5% of the marrow cells in CP and 10% or more indicates disease pro- gression 14821- Erythroid precursors vary but erythroid islan ds are usually reduced in number and size {222 11. The mega- karyocytes of CML are smaller than normal and have hypolobated nuclei ("dwarf megakaryocytes"). Although they may be normal or slightly decreased in number. 40-50% of patients exhibit moderate 10 extensive megakaryocytic proliferation 1296.775,2215.2221). The initial biopsy (WBC) count performed at the time of a routine medical examination is found to be abnormal 1486 . 755, 1942/. Common findi ngs at presentation inc lude fatigue. weight loss, night sweats, splenomegaly and anaemia 1486. 19421. Atypical pre- sentations include marked thrombocytosis unaccompanied by a significantly elevated WBC count as well as initial presentation in BP without a previously detectable CP 134,486. 17301. In the absence of curative treatment most patients progress from CP to BP either suddenly or through a transi- tcoat AP. although some die in AP without progression. The transformed phases are generally accompanied by worsened per- formance status and by symptoms related to severe anaemia, thrombocytopenia or marked splenic enlargement 17551. Morphology Chronic phase (CP) In CP the peripheral blood (PB) shows leukocytosis (12-1000x 1()lI1L. median - 1OQx1CPIL) due to neutrop hils in different stages of maturation wit h peaks in the percent of myelocyt es and segmented neutrophils 1486, 755, 1164, 1942, 20671. There is no significant dysplasia 1189 , 2458}. Blasts usually account tor less than 2% of the wac 1189, 206 7l. Ab solute basophilia is invariably present and eosinophilia is common (2067l. Ab solute monocytosis may be present but the frac- tion of rnonocvtes is usually <3% (1891. except in rare cases associated with the p 190 BCA -A8 L1 tsoto rm. in which case monocytosis is nearly always present and con fusion with chronic myelomonocytic leukaemia is possible 114581 The platelet co unt usually ranges tram normal to greater than 1000x1()91L and thrombocy- topeni a is uncommon 119421.The 8M cel- lularity is increased due to granulocytic proliferation with a maturation pattern sim- ilar to that in the blood 1486, 1534 1. In biopsy sections the paratrabecutar Cuffof imma ture neutrophile is often 5- 10 cells thick in contrast to the normal 2-3 cell layer and 1hemallie neutroph~sare situated in the intert rabecutar areas. Eosinophils may be prominent. Blasts usually account 9875/3 Sites of Involvement In CP, the leukaemic cens are minimally invasive and the proliferation is largely confined to naerocoieuc tissues, prima- rily blood. BM and spleen although the liver may be infiltrated as well. In BP, extra- medullary tissues, including lymph nodes, skin and soft tissues may show infiltration by blasts 1486,1029,15341. ICD-O code Epidemiology CM L has a worldwi de annual inci dence of 1- 2 cases per 100 ,000 po pulation. The disease can occur at any age, but the median age at diagnosis is in the 5th and 6th decades of life There is a slight male oreoorno ance 1755, 1053, 1826 1. Definition Chronic myelogenous leukaemia (CMl) is a myeloproliferative neoplasm thai originates in an abnormal pluripotent bone marrow (8 M) stem cell and is con- sistently associated with the BCR-ABL1 fusion gene located in the Philadelphia (Ph) chromosome {154. 1455 . 1607, 18841. Although the in.tial major finding is neutro- philic leW<ocytosis, the BCR-ABL 1is found in all myeloid lineages as well as in some lymphOid cells and endothelial cells. The natural history 01 untreated CML is bi- or triphasic: an initial indolent chronic phase (CP) is followed by an accelerated phase (AP), a blast phase (BP) or both. · 32 Myelop",lile"tive neoplasms
  • Fig. 2.04 CUL dVonicphase, "Pseudo-GaiI:: eels in CML.. APseucb-Gauchef cellsIn COITIllOl'Ily obsenoed i'l themarTOW aspIate$ aI pabents WIth CML. BThey Ina)' also be ~ as loamy or strialed eels in ITIlI"I'OW biopsy sedions. TheseI'listo:)"es are seaJndary " increased celllm::Ner. <We del'ived from theneopIaslic dln and easily~ from the &mal rnagakaryoc:yte tt-" rn8f9I"). stoNs moderate to marked reticulin fibrosis in approximately 30% 01 cases wh ich often correlates with inc reased numbers 01 megakaryocytes, larger spleen size andreportedly. a worse prognosis 1293 , 540, 1217.2215. 22211. Pseudo-Gaucher cells and sea-blue histiocytes are com- mooly observed secondary to increased cell turnover and are de rived 'rom the neoplastic clone 135. 22271. More than 80% ofpatients have significantly reduced or no iron-laden macrop hages 120451. In CP the spleen is enlarge d due to inliltration of the red pulp cords by granu- locytes in different mat uration stages , A similar infiltrate may be seen in the hepatic sinusoids and portal areas. Disease progressionltransformed phases in CMt The recognition of disease progression from CPto the transformed stages of AP and BP is important for prognosis and treatment, but the clinica l and morpho- logic boundaries between these stages olten overlap and the parameters used to identifythem have varied among different investigators [118, 293, 481, 482, 829 , 1100.194 11. Furthermore, there are only scant data relevant to disease progres- sion in the era 01 protein kinase inhibitor (PTKI) therapy. Bone marrow changes following short and long term PTKI treat- ment have been extensively studied showing a reduction 01 granulocytic eel- kJlaflly. normalization ofmegakaryopoiesis, regression of fibrosis and inc rease in eccctosis associated with decrease in proIilerative activity 122191. Accelerated phase (AP) In the 3ld edition of the WHO Classification 110391,it was suggested that the diagnosis of AP could be made if any of the follOwing parameters were present: 1) persistent or increasing WBC (> 10x1()9!L) and/or per- sistent or increasing splenomegaly unres ponsive to the rapy, 2) persistent mrontocvrose[> 1000xlcYlL) uncontrolled by therapy,3) persistent thrombocytopenia « 100xl()9!L) unrelated to therapy, 4) clonal cytogenetic evolution occurring after the initial diagnostic karyotype. 5) 20% or more basophils in the peripheral biooo. and 6) 10-19% myeloblasts in the blood or 8M. Criteria 1- 4 are more likely 10 be assoc iated with transition from CP to AP, whereas criteria 5 and 6 more frequently indicate a transition between AP and SP. Although modifications to Chronic myelogenous leukaemia. BCR-ABL I positive 33
  • A , Fi9. 2.05 Splenomegaly 11 CML AThe gross appearara ofItle spleen is solid and uniIonnIy deep red,although areas ofinlartt IlI8)' appear as IlghIer aIlouredregions, 8 TIll redpljp disbibubon of!tie infiltrate usually (XIll1lfesse5 alldobhlefates lhewhile pulp. CThe leukaemiCcells arepresent in!he SInuses aswei asin!he spleniccools oflhered pulp. these criteria have been suggested and different criteria proposed by others [4821. it is recommended tha t the param- eters listed above still be conside red as evide nce of disease progression. Whether they or other parameters, such as drug resistance, necessarily ind icate shortened survival times or imminent blast nanetor- mahon is not clear in view of the efficacy of current treatment strategies, and more studies are needed to accurately identify criteria for AP in the face of PTKI therapy. Often in AP the BM is hypercellular and myelodysplasia is seen 11534, 24581. The increase in myeloid lineage blasts may be readily appreciated with stains for CD34 performed on the biopsy 116501. large clusters or sheets of small, abnormal megakaryocytes associated with marked reticu lin or COllagen fibrosis are commonly observed and may be considered as pres umptive evidence of AP. although these find ings are almost always associ- ated with one or more of the other criteria listed above 1289, 293,15341. The finding of lymphoblasts in the blood or ma rrow is unusual in AP and should raise concern for lymphoblastic BP 15571. Blast phase (BP) The BP may be diagnosed when 1) blasts equal or are greater than 20% of the PB WBC orof the nucleated cells 01 the BM, or 2) when there is an extramedullary blast proliferation. In approximately 70% of cases. the blast lineage is myeloid and may include neutrophilic. eosinophilic. be- sophilic . monocytic, megakaryocytic or erythroid blasts or any combination thefeof. whereas in approxima tely 20-30% of cases the blasts are Iymphoblasts 1557. 1138. 1558, 1706. 1913,24541. In BP the blas t lineage may be ob vious morpholog- ically bu t often the blasts are primitive or heterogeneous and cytochemical and immunophenotypic analysis is recom- mended. If accumulations of bl asts occupy focal but significant areas of the 8M, e.q. an entire intenrabecular region, a presump- tive dtaqrosrs of BP is warranted , even if the remainder of the 8M biopsy shows CP 12891. Immunohistochemical studies lor CD34 andlOf terminal deoxynucleotidyl transferase (TdT) may help in distinguish- ing such foci of blasts in BP from the loci 01 promyelocytes and myelocytes thal often are prominent in paratrabecutar and perivascular regions during CPo Extramedullary blast proliferations most 34 Myeloproliferative neoplasms
  • F"tg.2.08 0r.I... myeloid bla~ ptlase. A~ l:tlodofl pllientWllh myeIoidbllst phase.Thtma;onty oftle "'* l:tlodoats<n blasts. B.C Sheetsof~ in'" bin! ITWTtM bqIsy. DMyeloperolidasedel8cllId Imu'oo tvmchei,U1.pIWng eemyetoid lineage ofhi blasl P'~lIlul. v- -- 0 0 II c:orrvnonly present in the skin. lym ph node, spleen. bone or central nervous system, but canoccur anywhere, and may be 01 myeloid orlymphoid lineage 110291. Irrm.oopheootyp The oeutrophils in CP have markedly decreased neutroph~ alkaline phosphatase {16401. In myeloid BPthe blasts may have strong. weak or 00 myetoperoxidase activity but express antigens associated withgranulocytic, monocytic, megakaryo- blastic and/or erythroid differentiation. In the majority of cases the myeloid blasts will express one or more lymphoid an ti- gens as well {557. 1138, 1558, 19 131. Mos1 cases of lymphoblastic BP are pre- cursor B in origin but cases of T lympho- blastic origin also oc cur p 138, 1558 , 19131. In lymphoblastic BP, one or more myeloid antigens are co-expressed on the ¥nphoblasts in the majority of cases, Ap- proximately 25% of BP cases fulfill criteria for mixed phenotype acute leukaemia (MPAL) 1557. 1138. 1558, 19 131, but these are considered as examples 01 BP and are different from de novo MPAL, Genetics At diagnosis. 90-95% of cases of CML have lt1e characteristic t(9;22)(q34:q 11,2) reciprocal translocation tha t resu lts in the Ph chromosome [der (22q)] 11607. 18841. This translocation fuses sequences of the BCR gene on ch romosome 22 with regions of the ABL1 gene from chrom o- some9 11541. The remaining cases either have variant trens'ocauons that involve a third or even a fourth chromosome in addition to chromosomes 9 and 22. or nevea cryptic translocation of 9q34 and 22<;11.2that cannot be identified by reo- tile cytogenetic ana lysis. In such cases, 'tieBCR-ABL 1fusion gene is present and C¥l be detected by FISH analysis. AT-PCR OfSouthern blot techniques 114541. The site of the breakpoint in the BGR gene may influence the phenotype of the ens- ease 11454). In CML, the breakpoint in BGR is almost always in the major break- point cluster region M~8CR . spanning exons 12-16, (previously known as b1-b5) and an abnormallusion protein, p210. is formed which has increased tyrosine kinase activity {14541. Rarely, the break- point in the eGR gene occurs in the 1J-8CA reg ion, spanning exons 17-20 (previously known as C1-C4) and a larger fusion protein, p230, is encoded. Patients withthis fusion may demonstrate prominent neutrophilic maturation and/orconspicUClUS throm bocytosis {1454, 16851. Although breaks in the minor breakpoint region, m-BCR (BCR exons 1-2) leads 10 a shorter fusion protein (pl90) and is most frequently associated with Ph positive ALL, small amounts of the p190 transcript can be detected in >90% of patients with classical p210 CML as well, due to alternative splicing of the OCRgene 11907, 23061. However, this breakpoint may also be seen in rare cases of CML that are dis- tinctive for having increased numbers of monocytes and thuscan resemble chronic myelomonocytic leukaemia 114581. The enhanced tyrosine kinase activity of BCR·ABL1 is responsible for coosntunve activation of several signal transduction pathways 15391. This resu lts in the leukaemic phenotype of CM L cells which encompasses deregulated proliferation, reduced adherence to the 8M stroma and defective apoptotic response to muta- genic stimuli . The understanding of the abnorma l signaling in CML cells led to the design and synthesis of small Chronic myelogenous leukaemia, BCR-ABL 1positive 35
  • A Penphetal blood smear. 8 Bone malTOW biopsy CMam:lw aspirate smear. Fig. 2.10 0Al..myeloid bIasIphase, in 8Ile~ site. A,8 l~ node biopsy obtainedfrom iI pabent witha tIiStor'y 01 CML lor3 ~_ The lymph node¥d1iteclln is Iatgely eIIaoad bya proIrfefatlon 01 medir.Jmkllarge Sizedcells. C l~ im~ confirms the myeloid lineage ollhe blasts, Fig. 2.11 Fluorescence il SItuhybAckzalion (FISH)withdual color anddualfusion probe on anormal metaphase eel (A)8Ild metaphase preparaOOn (8) from apatient witht(9-,Z2)(q34;q11 .2~ AWal alia' anddualfusion InInsloc:aIion probe is used (VysisRcorporatlon). The ABL I and BCRprobes arelabeled withSpectrumOrange and SpectrumGreen respecIJYeIy. In J'lOfmllI eels (A) two orange Signals represenbng the ABL1gene al 9q3.4 and two green SIgnals repre- senting the BCR at22(111.2are &hown. In thepall&nl's CMlcells (8) one orange (J'lOfmllI 9q34), onegreen (normal 22q11.2) andtwo orangeJgteen(yelOw) signals, repl"esenOOg derivative 9q3.4 and22q11,2, respedively, aredetected. molecules that target the tyrosine kinase activity of BCR-AB L1, of which imatinib was Ihe first to be successfully used to treat CML 1616, 6 171. lmatinib competes with ATP lor bind ing to me BCR-ABL1 kinase domain thus preventing phospho- rylation of tyrosine residues on its sub- strates, Interruption of the oncogenic signal in this way is very effective for con- trol of the disease , particularly when used early in CPoHowever, the emergence of sub-clones of leukaemic progenitor cells withpoint rrutations that prevent the bnding 01 the inhibilOf to the kinase domain of BCR-ABL 1 can lead to drug resistance, particularly in AP and BP 11103. 23731. The second generation compounds nilo- tmib and dasatinib can circumvent this form of drug failure in the case of most but not all kinase domain mutations associated with imatinib resistance 11103, 2373}. The molecu lar basis of disease transfor- mation is still largely unknown. Progression is usually associated with clo nal evolu tion 1657, 1487, 14881, and at the time of transformation 10AP or BP, 80% of patients demonstrate cytogenetic changes in ad- ditlOO to the Ph chromosome, such as an extra Ph, . 8, . 19, or i(17q). Genes shown to be altered in the transformed staqes in- clude TP53, RB1, MYC,p1f7'"""" {CDKN2Aj, RAS, AML 1and EVil, but their role in lhe transformation, if any, is currently unknown 1821, 1455, 14871- The recent introduction of genome -wide expression profiling by mrcroarray technology has started to reo veal other candidate genes associated with the advanc ed stages , and has also revealed similar gene expression patterns between AP and BP, suggesting that the genetic even ts lead ing to transformation in AP and BP occur in late CP or early AP 11608, 1624, 18031. Postulated celt oforigin It is currently accepted that CML-CP originates from a pluripotent 8M stem eel. However. disease progression may origi- nate in more corrvn itted precursors lhan previously supposed, as myeloid BP has been repor ted to involve the granulOcyte- macrophage prog enitor pool rather than the naerroooletc stem cell pool 114741. Whether the same applies to lymphoid BP is not known, 36 Mye loproliferative neoplasms
  • L- ---.J BCR.ABL1 l 813a2 .1402 p210 A m t?9;22)(q34;q11.2) B AlP-binding com etitors rig. 2.1 2 ... SC1lemabc representabDn of !he U:9:22) chromosomallranslocabon, me fusion mRNA ~ encoded by !he BCR..-&.1 tl)trid gene geoeqted in !he 22q.or F'IlIacletiIlia (PIlichi OliiO«Jmll, and hi nnslated BCR-ABL1kl5ion protOO, ...noseoncogenicptqlllrties I'e/y pl'lIl'IiIdy' on ts conslllUOVely actrvaledtyrosneU1aseen:xldedbytie s..:~ I ISH1)domain i'llicatedby ltle redOrde. Some of It1e oltlef~ UlcWlaI don'IaI'S CQ'1tnlluted bytie BCR andABLl pcnons oIlheOi iCClPioceifl n sI'lowfl. These n 1Ile dMnensaliOn domain (00): Vln wtlichis !tie allloptlosphoryllion s<1e cruciallor binding to008-2; the ptIospho-Ser and -ThrSH-binding dorr'I<Wl; a region turdogaIs tI Rho guarlIdne ru:Ieoticle exet.ange laclots(Rho-GE.F):ee ABll regoJa1o"y SH3 and SH2 domains; Y412 as !he map Slt8r:I~ wiltlillhe StU IrNse dcrnarI; ru::i8ar kx:att:alitw, J9IaIs (tt.S) and lhe DNA- and adn-I:imng danains.. BMectllnsm 01 adIion 01 acR-A8I..l yrtliW1e kNse ~ 'M1ereas h physdogicaI tning rJATP IIIitspoDelllbnBCR-ABLllO phosphorylate seIeded tyrosWle residues onrts SI.tIslrales (left<iagam). asynlheIicATP rrmc such lISinalinlb fits t1lspoct.ett,..Iiaopm),lluliXles nol prOYide IheesseoIiaIphosphate ~ lO be transfem!d k11he SI.tIslraIe Thedownstream d1aIn 01 reactions is lhenhaAed because,lfII'iltI irstyrosines i'llhe ~ form. ee subslrate does not assume the necessaryronJoonabon 10erlSlH associabon WIlh itS efleclor. ~ and predictive factors Based on historical data prior to any effective therapy, median survival times in CML ranged between 2-3 years {7671_ With conventional chemotherapy (busul- fan, Hydroxycarbamide) median survival was about 4 years, but progression to AP and BP was only slightly delayed with 10- year overall survival (OS) less than 10% 1767, 1948, 2022). Interferon-u-based regimes delayed progression signili- carttly, with median survival of approxi- mately 6 years and to-yea r OS of - 25% 1115l. With allogenic stem ceutransotant. 1O-yearOS ranges between 10 and 70%, depending on disease phase, patient age and donor type 1116, 828, 20221. Three prognosl ic models ba sed on baseline prognostic variables including age, spleen size, plate let count, the percent- age of mveiobrasts in PB as well as the percentage of basophils and eosinopnns in the PB allowed the calculation of rela- tive risk, hence of the life expectancy, of patients treated with conventional chemo- therapy and interferon 1905, 1101 , 2044 1 and with imatinib {116, 615), but not those treated with allogeneic stem ce ll trans- plant. Some studies have show n that the predictive values of these models can be further improved by the inclusion of mor- phologic parameters, particularly the presence or absence of myelofibrosis 1292, 293, 12 17, 12 181. Pretransplant myelofibrosis ha s been reported to be associated with a delayed or failure of naematoooenc reconstitution 1293, 22071. However, in the current era of PTKI therapy, the most important prognosti c indicator is the response to treatment at the haematologic, cytogenetic and mo- lecular level 1116/· Currently the complete cytogenetic response rate to imatinib is 70-90%, with a 5-year progression free survival and OS between 80 -95% 1116, 6151 Chrooc myelogenous leukaemia, BCR-ABL 1 positive 37
  • Chronic neutrophilic leukaemia B.J . Bain RD. Brunning JW. Vardiman J. Thiele Sites of involvement The PB and BM are always involved, and the spleen and liver usually show leukaemic Epidemiology The true incidence 01 CNL is unknown, but only about 150 cases have been reported. In one study 01 660 cases of chronic leukaemias of myeloid origin. not a singlecase01 CNLwasobserved 120031. CNL generally affects older adults. but has also been reported in adolescents 1909, 2474, 2504}. The sex distflbulion is nearly equal 1231. 640, 2474, 25041. Definition Chronic neutrophilic leukaemia (CNL) is a rare myeloproliferative disease . charac- terized by sustained peripheral bloOd (PB) neutrophilia. bone marrow (8M) hypercel- lulanty due to neutrophilic granulocyte pro- liferation. and hepatosplenomegaly. There is no Philadelphia (Ph) chromosome or BCR·ABL 11usion gene, The diagnosis reo quires exclusion of reactive neutrophilia and other myeloproliferative neoplasms, are almost never observed in the blood The neutrophils often appear toxic. with abnormal, coa rse granules, but they may also appear normal. Neutrophil dysplasia is not present. Red blood cell and platelet morphology is usually normal. The 8M biop sy shows hypercellularity with neu- trophilic proliferation. The myeloid:ery- throid ratio may reach 20:1 or greater Myeloblasts and prom yeiocytes are not increased in percentage at the time 01 di- agnosis, but the percent of mvelocvtee and mature neutrophils is increased. Ery- throid and megakaryocytic proliferation may also occur 1231, 24741. Significant dysplasia is not present in any 01 the cell lineages and, if found , another diagnosis. such as atypical chronic myeloid leukaemia. should be considered (See Chapter 4). Retic ulin fibrosis is uncom- mon 1231, 640, 2474, 25041. In view of the reported frequency of CNL in association with multiple myeloma, the BM should be examined for evi dence of a plasma ceu neoplasm 1355,584,2076, 20771. If plasma .. . :t I Fig.2.13 OvtncnewophIc ~ _ AThe neutrophiia dIatac:IeristIcoIltie ~ t*:xx1ilCNL B The.. granUatiolllXlr!JTllldy obset'o'ed. Reproduced from Anastasi and ~ (3SAJ. CThe bone rnatfOW asprDt SI!W der!lcmIrates neutrophil proWerabOn from myebcytes to ~ forms 'Mlh toO: granu/abOn, 1Mno olIW" s9'ificant abnormaibes. D The bone marrow biopsy specimen is hyperceWar, showing a markedly eIevMld myeIoicI:erylM:lid ratio WI!h increased IIJrmers ofnNrophk, partK:tarly maturesegmented bms. infil trates 12257. 2474. 25041. However, any tissue may be infiltrated by the rectro- phils 12257, 2474, 25041. Clinical features The most constant clinical feature reported is splenome galy. which may be sympto- matic . Hep atomeg aly is usu ally present as welt 12474 , 2504 1 A history of bleed ing from mucocutaneous surfaces or fromthe gastrointestinal tract is reported in 25-30% of patients 1909, 25041. Gout and pruritus are other possi ble symptoms 125041. --The PB smear shows neutrophilia with a wh ite blood celt count ~25x l ()9/L.. The neutrophils are usuatty segmented, but there may be a substantial increase in band forms as welt. In almost alt cases, neutrophil precursors(pn::rnyeIocytes, mye- iocytes. metemyetocytes) account for fewe r than 5% of Ihe white cells, but oc- casionally, they may account f()( ~p to 10% 1231,640, 909, 2474. 25041. Myeloblasts 996313ICD.Q code Etiology The cause of CNL is not known. In up to 20% of reported cases, the neutrophilia was associated with an und erlying neo- plasm, most usually multiple myeloma 1355, 58 4, 20761. To dale, no cases of CNL associated with myeloma have been reported in which a clonal chromosomal abnormality or evidenc e of cronauty by molecular techniques has been co nvinc - ingly demonstrated in the neutroonns 120771. II is thus likely that most cases of CNL associated with myelom a are not autonomous prolif erations of the neuuo- phi ls, but are secondary to abnorma l cvtokme release from the neoplastic plasma cells or other cells regulated by the plasma cell population. The same may be true of CNL associated with other neoplasms. However, it should be noted that evolution to acute myeloid leukaemia (AML) occurred in one patien t with CNL associated with multiple myeloma {5841. 38 Myeloprol iferat ive neoplasms
  • Table 2.01 Diagnostc criteria lor chronic neutroph~ iC Ieu~aemia. Peripheral blood leukocytosis, wac <:25xW/L 5e9mefltedneutrophils andband folms Bftl >80% ofwtlitebloodceas ImmatlKEl granu~es (promyelocytes, myebcytes, metamyelocytes) <10%ofwtlltebloodcells Myeiotllasts<1 %ofI't11ite blood cells 2. HyperceftlJarbonematTllW biopsy Neutrophilicvanuloc)1es increased II'l pen;enlage andnumber Myeloblasts<5%01 rWeated ITCIl'ltI'IIf' cetIs NeutmplVliC maluration paneronormal Megaka ~ normal orleft shifted 3. Hepatosplenomegaly 4 Noideflt! caJ5e lorptrysioIogic neutrophika or. if presanl, denw:lnslration 01 donaIiIy ofmyeloid eels bycytogenelic or molllo.I* studies Noinfecbous or J1lIarnmaIory JlItlC8SS No_.......5 NoPtlitadelphia cMlmo5omeorBCR-ABL1Mlon gene 6. No~ d PDGFRIo,PDGFRB orFGFR1 7. No~ ofpolyc'y1tlaenia vera. pti'Tlaty A'I)'elofibmsis oressential ~ 8. Noevidence 01 amyebcIysplaSllC ~ or amyeIodyspIasIicImyeloproleraliw neop(asms NogtafUcqtc dysplasia No myelodysplaslic changes II'l olher myeloid hages MonocyIes <hlO"IL cell abnormalities are present, clona lity 01 the neutrophil lineage should be sup- ported by cytogenetic or molecular tech- niques before making a diagnosis of CNL. Splenomegaly and hepatomegaly result from tissue inliltration by the neutrophils. In the spleen , the infil- trate is mainly confined 10 the red pulp; in !he liver. the sinusoids, portal areas or both, may be infutrated 12474, 25041. Cyll(:hen>stry The neutrophil alkaline phosphatase score IS usually normal or inc reased. but no OCher cvtocoencarabl"l()(mahty has been fepor1ed 1909.25041. """""'"CytogenetIC studies are ooemat in nearly 00% 01 patients. In the remaining patients, clonal karyotypic abnormalities may include +8, +9. +2 1, del(2Oq), del(11q) andde~12pl l566. 640, 736, 1415, 24661. Clonal cytogenetic abnormalilies may appear during the course of the disease. There isnoPh chromosome Of BCR-ABL 1 fusion gene. A vanant of chronic myel- ogenous leukaemia, BCR·ABL1 positive (CML) has been repo rted that demon- stratesperipheral blOOd neutrophil ia stm- ilar to that seen in CNL 116851. In such cases,avariant BCR-ABL1 fusion protein, p230, is found. Cases with this molecular variant of the BCR·ABL1 fusion gene should be considered as CMl , not CNL. Occasional patients with a JAK2rnutation have been reported [1083, 14351and this bassometimes been homozygous 110831. Ccrnplete cytogenetic remission with ima- tnib was reported in a patient with CNl and 1(15;19)(q13:P13.3), suggesling the possibility of an unidentified fusion gene in somecases 1433J. Postulated cell of origin Cell of origin is unknown. It is most likely a BM stem cell with limited lineage oo- tentiaI 1736, 24661. Prognosis and predictive factors Although generally regarded as a slowly progressiv e disorder, the survival of patients with CNl is variable, rangin g from 6 months 10 more than 20 years. Usually the neutrophilia is progressive. and anaemia and thrombocytopenia may ensue. Thedevelopment ofmyelodysplastic features may signal a translor mation of the disease to AML, which has been re- ported in some patients 1909, 25041. It is not clear whether the transformation was related to previous cytotoxic therapy in the cases reported. Chronic neutrophrlic leukaemia 39
  • Polycythaemia vera J. Thiele H,M, Kvasnicka A,Orazi A TeHeri G , 8irgegard Fig.2.14 SdJematic presentabOn ofee8YOIuliOn of1hedisease process ., ~ vera. 1 L.._ < 10 % Post-PVMFWIth biasbctransformation Post-polycythaemc myeIokl metaplasia (post-PV MF) .--_ _ 20 % Tennin.J1 sage 11 Sites of involvement The blood and 8M are the major sites 01 involvement, but the spleen and fiver are also affected and are the major sites of EMH in the later stages, However, any organ can be damaged as a result of the vascular consequences of the increased red cel l mass . - - - - - - -•• Transformation 1 t ~.Iy definite increase In red cell mass ...10"Jl,,;15'Mi ....21 Idl!!!9-U- I II Evolution _ Manifestation Etiology The underlying cause is unknown in most cases. A genetic predisposition has been reported in some famil ies 11778, 20321. Ionizing radiation and occupational exposure to toxins have been suggested as possible causes in occasional patients 1312}. Definition Poiycvtbaemra vera (PV) is a chronic myeloproliferative neoplasm (MPN) char- acterized by increased red blood cell production independent of the mechanisms that normally regu late erythropoiesis. Virtually all pat ients carry the somatic ga in-ol-lunction mutation 01lhe Janus 2 kinase gene, JAK2 V617F or another functionally similar JAK2 mutation thai results in proliferation not only 01 the erythroid lineage but of the granulocytes and megakaryocytes as well, t.e "pan- myelosis". Three phase s 01 PV may be recognized: (1) a prOdromal, pre- polycythaemic phase c harac terized by borderline to only mild erythrocytosis; (2) an overt poIycythaemic phase. associated witha significantly increased red cell mass ; and (3) a "spent" or post-oo'vcvtnaemic myelofibrosis phase (post-Pv MF) in which cvtooeruas. including anaemia . are associated with ineffective haemato- poese.bone marrow (8M) fibrosis. extra- medullary haematoooesrs (EMH). and hypersplenism, The natural progression of PV also includes a low incidence of evolution to a myelodysplastic/pre- leukaemic phase and/or to acute leukaemia (AML). All causes of secondary eryth ro- cytosis, inheritable po lycythaemia and other MPN must be excluded. The diag- nosis requires integration of clinical, labo- ratory and 8M histologica l features as outlined in Table 2,02 . Synonym Polycythaemia rubra vera, Table 2,02 Diagnosticcriteria lorpoI~emia vera (PV). Diagnosis requires thepresence 01 bottl majorcriteria and onemM criteriOn orhe presence ofthe firstmajor critel'orl togeth&r with two minor criteria.ICD-Ocode 9950/3 Majorcriteria t. Haemoglobin >18.5gJdL.,men, 16,5g!<ll in 'Io'OfT'l8l1 orother evidence ofeceeseo red cell voll,lTlEl' 2. Preserce ofJAK2 V617F orotnerfunctionaly slnVlar mutiltion sudlas JAKZe_on 12 rl'lI.ltalion I Epidemiology The reported annual incidence of PV increases with advanced age and varies from 0.710 2.6 per 100 000 inhabitants in Europe and North America. but is much Iavver in Japan 110591.Most reports indicate a slight male predominance, with the M:F ratio ranging from 1-2:1 ISO. 13891. The median age at diagnosis is 60 years . and patients younger than 20 years old are only rarely reported 117001. Minor criteria t. Bone marrow biopsy shoWing hypercellularily lorageWIth lJirIeage growttl (panmyelosis)wiltlprrITWIefll erytIvoid, granulocytic aodmegakaryocytJc proMerabon 2. serum erylhl'ClPClie'n levelbelowthe reIerenc:e range lornormal 3. EI'IOOgenous eryttvoid colony Iormabon II'l VItto • Haemoglobin Of haematoall >99th pertentileof rneIIlod-speofJ reference range lor age. sex, albtude of resideool a hael,qJobiI. >11gill. 10 men. 15Wdlin women • assoaaled WIth a doI:menlediIfld sustaned Mease of alleasl 2 gldL from an indMdual's baseline value Ilal tarl nol be attnbuted 10 correctlOn01 irOn defDency,orlll&vated redc:eI f'lIa$$ >25% llbovemun normal predicIer:l value 40 Myeloproliferative neoplasms
  • Fig. 2.15 F'dycylhaemiaveta, ~stage. AI.WcIy hyperc:eWa' bone IfilIJOIIWsI'oIro'rIga ~01 largemegakaryocytes in ee bone mafI'OW secUon. B Manylarge ¥ld gianttlyperIobuIated ( ET~ke) megak¥yotytes ina paleIIldilic:ally mrrickJng ET, because 01 a platelettxUlt inexcess 0I10D0xlO'1t-Note ee my dIy inaeased ~ lnf ef)'tt"ropoiesi (panmyelosis), beUerdlImDl ostraIed by~ esterase f9ClCtiOrL . Clinical features The major symptoms of PV are related to hypertension or vascular abnormalities causedby the increased red cell mass, In nearly 20% of patients an episode of venous or arterial thrombosis, such as deep vein thrombosis, myocardial is- chaemia or stroke, is documented in the medical history lSOI and may be the first manifestation of Pl/lSO, 197, 1389.20711. Mesenteric, portal or splenic vein throm- bosis and the Budd-Chiari syndrome should always lead to coosideration of PI/ asanIJlderlying cause and may precede the onset 01 an overt polycythaemic phase ISO, 2701. Headache, dizziness. visual disturbances and paraesmeses are major complaints, and pruntus. ery- thromelalgia and gout erealsocommon. In the full-blown polycythaemic stage physical findings usually include plethora and palpable splenomegaly in 70% and hepatomegaly in 40% 01 patients 11445, 20711. Clinical laboratory studies that aid in confirmation 01 the diagnosis of PV include subnormal erythropoietin (EPO) levels [223. 15271. endogenous erythroid c:oklny (EEC) formation15951. and oetectoo at the JAK2 V617F or functionally similar mutations, e.q. JAK2exon 12 mutations 11981,2168. 21771. Occasionally. patients may present with clinical symptoms suggestive of PV but WIth a haemoglobin level and/or red cell volume not sufficiently elevated to sub- stantiate the diagnosis. Such patients may be in the pre-oo'vcvtbaemrc phase, wtlichwaspreviously referred to by some authors as "latent PV' or as ' pure idio- pathic erythrocytosis" 1197,1559, 1715, 1697,2224), The detection of a subnormal EPO level, a JAK2V617F or funct ionally similar mutation andlor abnormal EEC lcmaton. in combination with the typical morphologic features described below, will allow the diagnosis of this phase of PV; these features are not found in secondary or spurious polycythaemia. The ore-ooivcvtnaemc phase may be expected tobecome overtly poIycythaemic ata later time. Maphology The morphological lindlngs in BM biopsy specimens at patients with PV must al- waysbe correlated with other clinical and taboratory fmd ings in order to firmly es- tablish the diagnosis 121771. However, eYennthe eartypre-po/ycyttlaemi stage the morphological findings are of sufficienl specificity to allow distinction of PV from secondary poIycythaemla as well as other subtypes of MPN 122031, Pre-polycythaemic phase and overt poIycythaemia Generally, in the pre-polycythaemic and polycythaemic phases of PV the major features in the peripheral blood (Pal and 8M are attributable to effective proliferalion in the erythroid , granulocytic and megakary- ocytic lineages, Le. there is pannweosrs. The PB shows a mild to overt excess of normochrcmie, normocytic red blood cells. If iron deficiency due to bleeding is pres- ent. the red cells may be hypOchromic and microcytic. Neutroptufia and rarely basophilia may be present. Occasional irrmature granulocytes may be detectable in the overt polycyttlaemic phase, but cir- culating blasts are generally not observed, Because of prominent thrombocytosis, up to 15% of cases of early phase PV may clinically mimic essential thronbo- cvthaerma (Ell 122101 but such cases eventually evolve into an overtly poly- cvmaemc stage 11047, 2007, 22101. PoIycythaemia vera 41
  • FIg. 2.11 AcuteIeukaen'ilWl poIycyth8emia WlflI. Blood ~ from apabenl M1h.~ Ilist:Iy ofPII. The patient had been treated with a/kyIabng agents !bing !he poIycyIhaemic stage. The blasts eeeseee C013. C033. C0117 alld C03-f. and had a compleJ karyotype.COf1SISlenl wrIh Il'lerapy-related aalte myeloid ....... Tabl.2.03 Diagooslicaileria fOf postiJOlycythaemic myelofibrosis (posl-PV MF) Required criteria 1. Documentation ofaprevious diagnosis of'MiQ.definedPV 2, Bone mallOlll1ibl"os4s grade 2-3 (000-3 $C8Ie) orgr-ade 3-4 (000- 4scale) Additionalcriteria (2 art rtquiredj 1. Anaemia' Ofsustained km ofei1hef pl1Iebotomy r~ theabseoce of~ therapy)orcytoreduc:M lrealmenl requilKnent b~s 2, Leukoel)1hroblaslic penpheral blood picbQ 3. Incteasll1g spIenornegllIy defIOlld as.rther aninaeasein palpable SPleoomegaIy of>S an from baseIint ldistaneefrom the left costal marg.n) OfIht1pp&afaflC8 ofnewly palpable spleoomegaly 4 Development of>1 of3consblulional symploms: >10%weighlloss i'l61'1'lC11'1tts, iWJhI sweats. unexplained Ie'o'eI' (>31.S 6 C) well as the distinction from reactive ery- throcytosis and thrombocytosis is feasible {2211 , 22221. Reticulin stains will show a normal reticulin libre network in about 80% 01 patients . but the remainder display increased reticulin and even borderline 10 mild collagen fibrosis {297, 641 , 775, 1189,221 1] depen ding on the stage 01 disease at first diagnosis, Reactive nodular lymphoid aggregates are found in up to 20% of cases {22031. Stainable iron is lacking in the 8M aspirate and biopsy specimens in more than 95% of the cases 1641, 22221. They typically tend to lorm loose clusters or to lie close to the bone trabeculae, and often show a significant degree 01 pleo- morphism with a mixture of different sizes. The majority of the megakaryocytes exhibit normally folded or deeply lobulated nuclei, and usually lack significant cytolog- ica l abnormalit ies, although a minori ty show bulbous nucle i and other nuclear abnormalities, particularly when associ- ated with a minor increase in reticulin {22111. When taking the characteristic histological pattern of PV into account, discrimination of PV from ET and PMF as Bonemarrow cellular ity has been reported to range from 35-100%, with a median cellularity of about 80% [641 1, but c har- acteristically the BM biopsy is hyperceuu- lar for the patient's age. A finding that is especially noteworthy is increased cellu- larity in the subcortical marrow space, an area which is normally nyooceuurar (775, 2203] Panmyelosis accounts for the in- creased ce llularity but an increase in the numbe rs of erythroid precursors and of megakaryocytes is often most prominent {641, 775, 22031. Erythropoiesis is normo- blastic, and granulopoiesis is mor pho- log ically normal. The pe rcentage of myeloblasts is not increased. Megakaryo- cvtes are increased in number. particu- larly in cases with an excess of platelets, and display characteristic morphological abnormalities, such as hyperlobated nuclei, even in the early phase of the disease, The presence 01 the panmyelo- sis, which although less prominent in the pre-poivcvtnaenc than in the overt poly- cythaemic phase, is nevertheless de- tectable and helps to distinguish early PV from ET,which it may otherwise resemble clinically 122101·As in the pre-pdycythaefr phase, megakaryocytes seen in the poIycythaemic stage 01 PV are clearly distinguishable from those seen in ET. 42 MyeloproliferatIve neoplasms
  • Fig. 2.19 ~ Ylll'a, ~ rnyelofbosis (pos&-PV MF)and"¥lbd metaplasia, splerJedoi"r specinen. Thesplenic enlarvement in the~ ptIase isdue IlIMlIy b eJb"ameOJlary Ilaema!DpoIesis !hat Cll:X:ln II1 It1e splenic sftlses,as wei 11$Iibrosis.-.d lll1trapmenl d platelets and tIaernalopoieli eels II1lhe splenic coos "Spent phase"and post·polycythaemic myelofibrosis (oost-Pv MF) During the later phases of PV, erythro- poiesis progressively decreases. As a consequence, the red blood cell mass normalizes and then decreases, and the spleen further enlarges. Usually these Changes are accompanied by correspon- ding8M aneranons 1641 . 20711. The most common pattern of disease progression is posf-Pv MF accompanied by myeloid metaplasia which is characterized by a Ieukoerythroblastic PB smear, poikilocy' ioss wilh teardrop-shaped red blood cells. and splenomegaly due to EMH , as defined in Table 203 {143A). The mor- phological hallmark of this slage of the disease is overt reticulin aOO collagen fbrosisofthe BM 1641 . 775, 2203, 22221, The CelkJarity varies in this terminal stage. tu: h'y1:loceIIular specimens are coreroo. CUsters of megakaryocytes, olten with hyperchromatic and very dysmorphic nuclei, are prominent Erythropoiesis and granulopoiesis are decreased in amount. and are sometimes foun d . along with megakaryocytes, lying within dilated mar- rcw srcsocs 122031. Osteosclerosis may also occur 164 1, 7751, The splenic en- largement is a consequence of EMH, ....nich ischaracterized by the presence of erythroid. granulocylic and megakary- ccvnc elements in the splenic sinuses and cords of Billroth. An increase in the number of immature cells may be ob- served in these stages, butme finding of ) 10%blasts in the PB or 8M or the pre s- ence of signific ant myelodysplasia is unusual, and mosl likely signals tran sfor- mation to an acce lerated phase and/or a myelodysplastic syndrome (MDS), Cases inwhich 20% or more blasts are found are cnsoerec AML 11701, 2071, 2203, 2222). """"phenotype No abnormal phenotype has been reo "",eo Go'o'" The mosf frequent genetic abnormality in PV isthe somatic qam-ot-tuncnon muta- too JAK2 V617F. Although il occurs in >95%ofpatients with PV, it is not specific and isfound in other MPN as well. but in iower freq uencvltea. 1044,1 186, 12881. The mutation occurs in a haematopoielic stem cell, and is found in all of the myeloid lineages. Hence cells that utilize JAK2 kinase in the intracellular signaling pathway may be hypersen sitive to growth factors and other cvtokmes. including EPO. A fun ctionally similar mutation in exon 12 of JAK2 has also been reported 11981/. so that virtually all patient s with PV have a JAK2 aberration , Still, no genetic defect enti rely specif ic to PV has been ide ntified . At diagnosis, cytogenetic ab normalities are detectable in about 20% of patients. The mo st common recurring abnormalities include +8, +9, del(20Q), de l(13q) and del{9p): some- times +8 and +9 are found tog ether 142, 2394/. There is no Philadelphi a chromo- some or BCR-ABL 1 fusion gene. These chromosomal abnormalities are seen with increasi ng frequency with disea se pro- gression and in nearly 80-90% of those with post-PV MF 1421, Almost 100% of those who develop MDS or AMl have cyt ogenetic abnormalities. including those commonly observed in therapy-related MDS and AMl (See Chapter 6). Postulated cell of origin Heemetopoteuc stem cel l. Prog nosis and predictive fact ors With currently available treatment, median survival limes > 10 years are commonly reported {SO, 1215, 1548,2071/. although controversy persists about the risk factors other than olde r age {1215, 1389, 17021. Most patients die from thrombosis or haemorrhage, but up to 20% succumb to myelodysplasia oracute myeloid leukaemia ISO, 1389, 20711, The factors tha t pred ict the risk of throm- bo sis or haemorrhage are not well defined 11389, 1700,20711, The incid ence of MDS and acute leukaemic transforma- tion is only 2-3% in patients who have not been treated with cy totoxic agents, but increases to 10% or more following certain types of chemotherapy {704 , 1389, 1548, 170 1, 17021_ PoIycythaemlCl vera 43
  • Primary myelofibrosis J. Thiele H M. Kvasnicka A. Tefferi G. Barosi A. Orazi JW. Vardiman Minor aiteril 1 .l~ ' 2. Increase on serum lactatedeIlydrogerIase level' 3, AraemIa. , S""""""",, I Smallto largemegakaryocyteswith anaberrant nuclearlcytoplasmic ratiO andhyperchromatic, bulbous,or irregularly loIded nuclei anddense clustering b Requires !he lailure 01 ironrnpiacemenllherap)'toincreasehaemoglobin level 10 tile potycythaem~ vera range inthe presence01 decfeased serum fembn.ExckJsion ofpoIycylhaemia vera is based onhaemoglobin and haematocrit levels.n red eel massmeasurement is not required, < Requns the absence oIBCR.ABL.1 , " Req!.ns atlMnce01 dyW)'ltliopoiesi$ and:~. • PatientsWIth an:libons associaled wilhreactve Ill)'IlIofitlro llfe not mn.onekl PMf. ;rod .. ~ stxUd be COIlSide1lldn std1 cases~ olhercntena aremel I Degree ofabnorrnalIIy couldbe borderline or martell. Table 2.114 Diagnos1ic crilefialor primary myelofibrosis:<iagnosis requiresmeetingall 3 mator and2 miroof crileria MaiOI'eritltria t. Presenced ~ ...........1n atypiI", usuaIylaXllTlpalied byllitlerreIla*l inlier a:tagen ~ '"nileabsenat d sig1Icat /W)Jin Iibrosi:s, tle ~ chat'gesIl'LISI be llCClJI'llliDedbya'l 1lcJeaged bone ITI8fTOWcelIularrty characlenzlldbygranuIol:yIic pn:jferabDn and often deaea:Sed erythn;lpooesis ~ e. p!VftlroIic ceItEr-pllase disease). 2. Not meeting WHO Criteria lorpoIy<:ythaemia~. BCR·ABLt+chronic myeIogeoous leukaemia'. myelodysplaslicsyndrome'.fJ( other myejoid neoplasms 3. Demonstration of JAK2 V6t7F orother donal marker(e,g. MPL W515K!L), '"inthe absence 01 a clonalmarker. 00evidence lhatlhe bone marrow fibrosis et otherc:Nlnges aresecondary klmecoon.autorr1rrone dison:ler r:K0lIlerchronic I1ftarnnatory t'a'llIIJon hairyC8lI ~ et OCher IyrnJ:tMjd neoplasm,metasta1ic mal9'ancy. et klxiC (etvonic) myeIopaltlies" Etiology Exposure to benzene or ionizing radiation has been documented in some cases {5881 Rare familial cases of 8 M fibrosis in young chil dren have been reported How often this represents an MPN is ~ known. but at least somecasesappear 10 represent an autoscmal recessive imented oondilioo 118731· In oee- families with a somewhat later age of onset. the leal1.Xes havebeen consistent withanMPN,suggest- ing a familial predisposition to PMF 13691. Sites of involvement Blood and BM are always involved. In the later stages of the d isease, EMH (also known as myeloid metaplasia) becomes prominent, in particular in the spleen 117731. In the initial stages. randomly dis- tnbcted C034+ prOlJenitors are slightly in- creased in the 8 M. but not in the peripheral blood {PBl· Only in the tate stages they appear in large numbers pe- riphe rally (1592, 22091 This increase of CD34+ ce lls in the PB is a phenomenon large ly restric ted to overt PMF and is not seen in non-fib rotic po lycythaemia vera (PV) or essential thrombocythaemia (ETl 141,145,17031. It has been postulated that EMH is a consequence ot me pecu- liar ability of the spleen to sequestrate the numerous circulating CD34+ cells 122081. Liver. lymph nodes. kidney adrenal gland. dura mater, gastrointestinal tract, lung and pleura. breast skin and sott tissues are other possible sites of EMH 1216n Clinical featu res Up to 30% of patients are asymptomatic at the time of diagnosis and are discov- ered by octcctco of splenomegaly during a routine physical examination or when a routine blood count discloses anaemia. leukocytosis and/or thrombocytosis. Less commonly. the dia gnosis results from discover y of une xplained teukoervmro- btastosisor an increased lactate dehydro- genase (LDH) {366 . 2167, 21771. In the initial prefibrolic phase of PMF. the only finding may be marked thrombocytosis mimicking ET 12177,22011. Therefore. a sustained thrombocytosis cannot. by itself, discriminate between prenbrotc PMF and ET 12201, 2202. 22041. Constitutional symptoms may include fatigue. dyspnoea. weighl loss, night sweats. Iow-grade fever 9961/3ICD-O code Synonyms Chronic idiopathic myelofibrosis (CIMF); Agnogenic myeloid metaplasia (AMM); MyelofibrosiS/sclerosis withmyeloid meta- plasia (MMM); Idiopathic myelofibrosis. Epidemiology The overt fibrotic pha se is estimated to occur at 0.5-1,5 per 100 000 persons per year {1060,21671. It occurs most C()fTV'TK)ll1y in the sixth 10seventh decade of life, and both sexes are nearty equally affected 121671. Children are rarely affected 136n Definition Primary myelofibrosis (PMF) 114641is a clonal myeloproliferative neoplasm (MPN) characterized by a proliferation of pre- dominantly megakaryocytes and granulo- cytes in the bone marrow (8M) that in fully developed disease is associated with reactive deposition of fibrous connective tissue and with extramedullary haema- topoiesis (EMH) . There is a stepwise evo- lution from an initial prefibrotic phase 121771 cha rac terized by a hypercell ular BM with absent or minimal reticulin fibrosis to a fibrotic phase with marked reticulin or collagen ubrosrs in lhe 8M and often osteosclerosis. This fibrotic stage of PMF is characterized by ieukoervtbrobiastosis in the booo witllteardrop-shaped red cells. and by hepatomegaly and splenomegaly (Table 2,04). 44 Myeloproliferative neoplasms
  • Evolution _ Manifestation -----•• Transformation clusters of variable size that are frequently edrecent tc 8M vascular sinuses and the bone trabeculae 1297.775,2204.22161. Most megakaryocytes are enlarged, but small megakaryocytes may also be seen, and theif detection is greatly facilitated by the use of immunohistochemistry with an- tibodies reactive with megakaryocytic antigens 12201, 22041. Deviations from the normal oucrear.cvtoptasmc ratio (an expression of defective maturation). an- normal patterns of chromatin clumping with bulbous, "cloud-like" or "balloon-shaped" nuclei , and the frequent occurrence of bare megakaryocytic nuclei are all typical findi ngs, Overall in PMF the megakaryo- cvtes are more atypical than in any other type of MPN. Vascular oronteeanon is 1297.775.2202,22041_In these cases the BM biopsy is nvperceuotar with an in- crease in the number of neutrophifs and atypical meqaaarvocv tes. There may be a mild "left shin- in granulopoiesis, but usually metamyelocytes. bands and seq- mented forms predominate. Myeloblasts are not increased in percentage. and con- spicuous clusters of blasts or of CD34+ progenitors are not observed {2202 , 22041_ In most cases, erythropoiesis is reduced in qua ntity. but early erythroid precursors are prominent in some pa- tients 122281_The megakaryocytes are markedly abnormal, and their ntstotoco- graphy and morphology is the key to the recognit ion of the prefibrotic stage of PMF, The megakaryocytes often form dense GJ ~ CD e;,.",d MF-O MFoI Mf.2 Mf.] ~ _ I 11 I Prefibrotic:-early PMF AdYilnced PMF (MMHJ Fig. 2.21 ~ oI lhe disease process11'1 PfWnarY lIlJ8lDIiblosis (PMF)withassocialed ~ (lata (rr'IllCWI values)aridassociaIed fibre ~ - initiat Biage and bleeding episodes, Gouty arthritis and renal stones due to hyperuricaemia may alsooccur. Splenomegaly of varying degee isdetectedin up to 90% of patients and may be massive: nearly 50% have t'epa!l:megaty 1143, 366. 367, 1635, 21671. The JAK2V617Fmutation may be found n ~50% atpatients in the fibrotic phase: itsincidence in the prefibrotic stage has no!beenwellstudied. Althoug h helpful in disllnguishing PMF from reactive condi- boos thaI may result in 8M fibrosis, the mutation is not specific for PMF but is tound in PV and ET as well 121721. -The classical picture of advanced PMF includes a PB smear that shows leuko- erythroblastosis and anrsopo'knocvtosrs (particularly with teardrop-shaped red cells) associated with a hvp oceuurar BM with marked reticulin andlor collagen fibrosis and organomegaly caused by EMH, However, the morp hological and clinical findings vary considerably at diagnosis depending on whether the patient is first encountered during the prefibrolic or the fibrotic stage of the disease (2177, 22041. Because the pro- gressive accumulation of fibrous tissue parallels diseaseprogression, it is impor- tant to reproducibly and sequentially grade the amount of BM fibrosis semi- ~ntitatively by using a sCOfing system 122141(Table 2.05). PreffJroticandearly stage PMF:Noregistry- based prevalence ligures are available b"theincidence otme prehbrotic phase olPMF, but series derived from various 'llfereoce centres reveal that 30-40% of patlerlIs arefirsl detected in a prodromal, preltbmllCphase without a significant in- crease in reticulin and/or collagen fibres Primary myekllibrosis 45
  • GflIding 08$criptlon' Tlble 2.05 SemiQuanlitati~ grading ofbone marrow fibrosis (MF). I I acute phase. In cases with 20% Of more blasts in the PB and/Of8 M at presentation in which other find ings may suggest PMF, the diagnosis 01 acute leukaemia shOOd be made with only mentiOnof the possible derivation from PMF. MF• 0 Scatlemd ftar reticulin WlItl ro IOte~ (CIOS$-OWlI'S),CO!reSpCJnding tonormal booemarrow MF- 1 loose networt ofreliaJlinwltlmany i'ltersections,especiallyinperivasa.dar ereas MF- 2 Diffuse arr:l dense increase InrebaJlin wrtll eJ:tenSlYe intersedtons. occasionally 'frilh local burr:lles 01coIagen and/orlocal OSleosderosis MF- 3 0l1fuse and dense II"lCl'eaSe IIIreticulin 'M!tl extensive II'IIer$edIons ilIICl coarse bundles of collagen, often associated 'frilh ~ ~~~) ..Fig. 2.23 Primary myelofibrosis, fibrotic stage, WlIIl ellrameduallary haemalopoiesis in Iivet. A In the Mr,tie sirtUSOids are prominenUy involved by bilineageprolilerallOll. B Megakaryotyles are the hallrnart.01 abnonnll irltrasinusoidal haematopoiesis. an a normal endosteal location in the 8M 12204. 22091. ind icate an accelerated phase of the disease, whereas ~% blasts is considered as acute uanstome- teo. Patients with PMF may also present initially in an accelerated phase Of an usual in the 8M 11 2141, and lymphoid nodules are found in about 20% to 30% 12201, 22041. Careful 8M morphological examination is particularly crucial in dis- tinguishing pretiorotrc PMF with accom- panying thrombocytosis from ET 1712. 796,2177.2201.22161. Reticulin fibrosis is minimal or even absent (correspondin g to grades 0 and 1)during this stage 122141; if present. It is usually focal and tend s to be concentrated around vessels . The rna- jority of cases with pretrbrotic and early (reticulin) fibrot ic stages of PMF eventu- ally transform into overt ubronczscrerotrc myelofibrosis associated with EMH 1295. 775. 1189, 2204. 22181. Fibroticstage: Most pat ients with PMFare initially diagnosed in the overt fibrotic stage 1143, 366. 1635, 21671. tn this stage the 8M biopsy demonstrates clear-cut reticulin or collagen fibrosis (fibrosis grades 2 and 3). The 8M may stilt be focally nvpercenurer, but more often is normocellular orhypocellular. with patches of active naerretopoeers alternating with hypocel1ular regions of loose connective tissue andlor fat. Foci of immature cells may be more prominent. although myelo- blasts account for < 10% of the 8M cells {297, 775. 22041. Atypical megakaryocytes are often the most conspicuous finding ; these occur in large clusters or sheets, often within dilated vascular sinuses 1295, 2204). Sometimes lhe 8M is almost devoid of haematopoietic cells, showing mainly dense reticulin or collagen fibrosis, with small islands of haematopoietic precursors situated mostly within the vascular sinuses. Associated with the development of myelofibrosis is a significant proliferation of vessels showing marked tortuosity and lu- minal distension, often assoc iated with conspicuous intrasinusoidal haemato- coese (1214, 1347, 1463). Osteoid seams or eooossionarnewboneformatioo in bud- like endophytic plaques may be observed {775, 22041. In this osteosclerotic phase. the bone may form broad, irregular tra- beculae that can occupy >50% of the 8 M space. With exception of allogeneic stern cell transplantation 11592. 22131, develop-- ment of myelofibrosis in PMF is not signifi- cantly influenced by treatment modalities. and is obviously related to disease pro- gression 1295.2217, 22181· In patients with a previously established diagnosis of PMF, the finding of 10-19% blasts in the P8 and/or 8M and the oerectco by immuno- histochemistry of an increased number of CD34+ cells With cluster formation and/or 46 Myeloproliferative neoplasms
  • Fig.2.24 PrWncwy myeIoIilrosis. 6brollc stage. AThIs penrtIerBl bloodsme<I" shows dac:ryotytes.occasionalnu::MaIed redbloodeels <n:I irrrnalJ..nI grarUocytes ~l . BAdilaIed sinuscorrtans inmaIIft tIaerrI.1qloiet elements, most notably megakaryocytes (p,f,$stain). ThiS intrasinusoidal haematopoiesi$ togetheroMth VilSClAr pn:iIeralJon ischaradetisbcbutnotliagl'105bC ofPMF WIth myeloid rneIapIa:sia. CMegakaryocytesareolen the IOO5t conspicuous haemalopoielicelement il the marrow Often !he cells appearto"'s1ream"1I'rough themarrow due 10the In:lerI)tlg fitrosis. 0 Mcrled retJctjn and o:tagen Mln:lsII aSD:iated withasrreanHke arrargemenI ofmegakMyocytes arldinitial osteosclerosis is$hoIrm (slYerstaIn). I Extramedullary baenatoooleeta The most common site of EMH is the spleen , followed by the liver 117731. The spleen shows an expansion of the red pulp by erythroid, granulocytic and megakaryocytic cells. Their identification can be aided by immunohistochemistry [16 13, 2 1991. which also allows an ap- preciation of an increase in neoanqioqen- esis /144 . Megakaryocytes are often the most conspicuous component of the EMH. Occasionally large aggregates of rreqakeryocytes. growing COhesively. can ooocce macroscopically evident tt.mOUral lesions. In the presence of nodular lesions and, in general. in any advanced stage disease with large amounts of EMH, the PQS&bility 01 a myebd sarcoma should be c:onsidefed and carefully excluded by per- laming irrmunohistological studies with CD34 117731. The red pulp cords may exhibit fibrosis as well as pooling 01 platelets. Hepatic sinuses also show pr0mi- nent EMH. and cirrhosis of the liver may occur /21671. Immunophenotype No abnormal phenotypic features have been reported. Genetics No genetic defect specific for PMF has been identified 11832AJ. Ap proximately 50%of patients with PMF exhibit the JAK2 V617Fmutation. Although the presence of the mutation confi rms the croneltty of the proliferation, it is also found in PV and ET and thus does not distinguish PMF from these MPN {163, 1044, 1064, 1186, 1288J. A functionally similar ga in-o f-func tion mutation of MPL (MPL W5 15K/l ) has been reported in up to 5% at PMF cases. but in occasional cases of ET as wen /16891.Cytoge netic abnormalities occur in up to 30% of patients (630, 1832, 21741. There is no Philadelphia chromosome or BCR·ABL1fusion gene. The presence of either del( 13)(q12-22) or der(6) t( 1;6) (q21-23;p2 1.3) is strongly suggestive but not diagnoslic of PMF [5861. The most common recurring abnormalilies include del(2Oq), and partial trisomy 1q, allhough +9 and/or +8 are also reported {63O. 1832A, 21741. Deletions aNeeting the long arms of chromosomes 7 and 5 occur as 'Nell. but may be associated with prior cy- totoxic therapy used to treat the myelo- proliferative process. Postulated cell of origin Haematopoi etic stem cell Prognosis and predictive factors The time of survival in patients with PMF ranges from months to decades. The overall prognosis de pends on the stage in which PMF is firstly diagnosed 11215. 22041. The median survival time is ap- proximately 3 to 7 years in patients diag- nosed in the fibrotic stage {142, 366. 367. 630, 2 167/. which contrasts with a 10- and ts-vear relative survival rate of 72% and 59% respectively, in patients diag- nosed in the early prefibrotic phase 11215. 12191. Factors at presentation that adversely affect pro gnosis include age >70 years. Hb <10 g/d l , platelet count <100x l ()6/l , and an abnormal karyotype 11 42, 143.366,630, 12 15, 12 19, 1832A, 2105 ,2174,22041. The major causes of morbidity and mortality are 8M failure (in. tecnon . haemorrhage). thromboembolic events, portal hypertension, cardiac failure and acute leukaemia (AMl) {21671. The reported frequency of AMl ranges from 5 to 30% 1366, 630, 21671. Although some cases of AMl are related to prior cyto- toxic therapy. many have been reported in patients who have never been treated, confirming that AMl is part of the natural history 01 PMF Primary myelofibrosis 47
  • Essential thrombocythaemia J. Thiele H M. Kvasnicka A.Orazi A. Tefleri H. Gisslinger 1. SllSIairled' platelet count ~45Ox 10"1t 2. Bone marrow biopsy specimenshowing proliferation mainly ofthemegakaryocyticlineage withincreased nlll'11bers of9l1larged. matul'tl megakaryocytes.Nosignllical1t increase Of Iefl-sMtofOOlItrophiI glanoo- poiesis orer,1IWOpoiests 3. Not meetlng WHO atSerialorpoIycyIIlaema vera,· P'JI'Nf'Y myelofIbrosI$.<BCR-ABL f posiWect.ror.: myeIogenouIlMaetnia' ormyeIodysplaslic syndrtml" Of oIhermyeklid ~ 4. Demonstration 01 JAK2V617F orolherdonal maricer.or in!tie absenteofJAK2V617F, noe-.1dence lor reeceve thrombocy1osls' • Sustatned ooring the W(ri.-up process. • Requires Itle fcMure ofironrepIaoement ItIefapy toincrease IIaemoglcOf1 level10I!'oe polyc)1IIaemia "'llfa fange Illhe presenceofdeaeased serum lerTilin. Ex<iJsion ofpo/ytyltIiIllfllia vera is basedonhaemoglobin rod hilemiIIocrtIeve!s and redeel mass meiISl.Ifement isnot required. • Req.wes!he absence 01 relevartre!iQjn Ibosis. coIagen fitl«l&s, ~ ~~ , Of markedly hyperceIuIar marrow aetOll"C'3ried bymegakaryocyte IIUphoIogyIhat III lypicaI for primary myelofibrosis ifIcludtng smaH 10large rnegakaryocytes WIth anaberranl nuclearl~smic ratioiIfId hyperchromatic. bulbous Of irregularlyWed noc~ anddense dusterirlg. • Requirestheabsence of BCR·ABL1. • Requires abser'loe ofdyserythlopoies and llysgranulopoiesis. , Causes ofreactivethrombocytosis iIdude I/'Ofldeficiency. splenedomy. StJfgefY. nedion. inllammation. alM8CtIVe!lssue disease. melastIticcancer. and ~trve disorders However. the presence of a cendIOOn iIS800ated wllll reactiveborrtlocyt)sis may noI edJde fie possility d ET 't!he fnl wee criteria are met Clinical features More than one half of patients are asvrrp- tomaucwhen a markedly elevated platele! count is discovered lortUitously at the tJml! of a routine PB count 1705, 802, 902- 21751. The remaining patients preset with some manifestation of vascular occlusion or haemorrhage 1210, 4581 Microvascular occlusion may lead to trarl- sterniscnaemc attacks, digital ischaemia with paraestheeias. and gangrene 1210. 458 . 1473. 18291. Thrombosis of map arteries and veins also occur. and ET may be a cause 01 splenic or hepatic veil thrombosis as in the Budd-Chiari syn- drome. Bleedi ng occurs most comrrow from mucosal surfaces. such as the gas- trointestinal trac t or upper airway pas- sages 1379. 802, 1549. 19551. If h criteria established by lhe PVSG 101 E1 are used. mild splenomegaly is present approximately 50% of patients at diagnosrs and hepatomega ly in 15-20% 1705, 802. 902, 1549, 2 1751 However, when !he WHO classification is applied and pa- tients with thrombocytosis associated the prelibrotic stage 01 primary myeIcj. brosis (PMF) are excluded. spIencrneg<I, is seen in only a minority of patients ET112151. Rare patients who meet the terra for ET have been reported to half noncronat meqakervocvtoootests eoe I tower incidence of thrombo tic epi 19011. kry relationship of such cases 10 vast majority of cases 01 ET that clonal haematopoiesis is not clear. Sites of involvement Bone marrow and blood are the principal sites of involvement. The spleen does not show signilicant extramedullary haemato- poesrs (EMH), but is a sequestration site for platelets 1705.902. 21751. EtiOlogy The etiology of ET is unknown. Epidemiology The true incidence of ET is unknown, bu t when diagnosed according to the guide- lines of the Polycythaemia Vera Study Group (PVSG) is estimated 10be 06-2.5 per 100 000 persons per year {1055. 10591. Most cases occur in patients 50-60 years 01 age, with no major sex predilection. However, a second peak in frequency, particularly in women, occurs at about 30 years 01age 1705. 902. 10551. ET can also be seen in children, albeit in- frequently 118151, but must be distin- guished from rare cases 01 hereditary thrombocytosis 1585. 24011. 9962/3IC[).() code Synonyms Primary thrombocytosis: idiopathic mrom - bocytose, haemorrhagicthrcrnbocythaemia. Defin ition Essen tial thrombocythaernia (Ell is a chronicmyeloproliferative neoplasm (MPN) that involves primarily the megakaryocytic lineage. It is characterized by sustained thrombocytosis <!:45Ox l()1'A.. in the periph- eral blood (PS), increased numbers of large. mature megakaryocytes in the bone marrow (8 M), and clinically by episodes of thrombosis and/OI' haemorrhage,Because there is no known genetic or biological marker specific lor ET. other causes for thrombocytosis must be excluded, in- cluding other MPN, inflammatory and infectious disorders, haemorrhage and other types of haematopoietic and non- haematopo ielic neoplasms. The presence of a BCR-ABL 1fusion gene excludes the diagnosis of El 48 Myeloproliferative neoplasms
  • f ig. 2.27 Essential ttwombocylhaerma, bone marrow aspl'ate smear. AAll increase in the nurrtler and sizeofthe megailaryocyles. BNoIe thedeeply Iobutaledmegaka'yocytic ~, aswell astarge pools01 plate~_ Note thatthe aspirate smears fail toreveal the overall marrow archilectureanddistribution ofthe rnegar.aryocytes thatcan be (Illy seen inthe biopsy, Inee past, the platelet threshold for the diagnosis of E'r was :!:600x109/l11549J, but some patients have haemorrhagic or ltuombolic episodes at lower platelet cents 11272, 1829, 19031. In order not to C01lprcmise the diagnosis in such cases, anumber of investigators convincingly arguedtOl" a lower platelet threshold for ee diagnosis of ET. and the WHO has adoptedthe recommendation of a platelet COltlt ~450x 1 l)l'IL, a value that exceeds !he 95th percentile for normal platelet counts adjusted for gender and race (1272. 1897, 1903.21771. Although this llYeshoid will encompass more patients 1Io'!lh ET, it will also include more patients 'I4lCCflditions that mimic ET. It is therefore essential that all Criteria listed in Table 200 for the diagnosis of ET be met to ex- ewe olher recotastc and non-neoplastic causes 01 thrombocytosis 121771. The 8M bi:psy is particularly helpful in excluding ere myeloid neoplasms associated with excessiveplatelet counts. such as myelo- dysplastic syndrome (MDS) associated wltrl isolated del (5q). the provisional 'l'r)'eIodysplasticlmyeloprohferative entity refractory anaemia with ring sioerobrasts and thrombocytosis (AAAS-T), and the cetoronc phase of PMF. Althou gh the JAK2 V617F mutation is found in only 40-50% ot cases of ET and is not specific b' ET, when present it does exclude re- ectvemrorroocvtosrs 121771. Similarly, in eeoenocqeroueerythroid and/or mega- karyocytic colony formation, althoug h not specrlic tor ET, also excludes reactive ltYombocytosis 15941. Mo'phology The major abnormality seen in the PB is marked thrombocytosis, The platelets often display anisocytosis, rang ing from tiny torms to atypical large, giant platelets. Bizarre shapes, pseudopods and agranular platelets may be seen, but are rot common. The white blood cell (WEq count and Ieueocyte differential ~e usually normal, although a borderline eevaton in the WBC count may occur (705,802.902, 21751. Basophilia is usu- aMy absent or minimal 115491_The red blOOd cells are usually normocytic and rcerccnrcnc unless recurrent haerror- mage has caused iron deficiency, in W"Mch case they may be hypochromic and microcytic. Leckoervtnrobleetosts ¥d teardrop-shaped red blood cells are IQ seen I'l ET 121751. ~ rrosl cases, the BM core biopsy shows a normocel lular or moderately hypercel- lular 8M {775, 22161. The most striking ab- normality is a marked proliferation of megakaryocytes with a predominance of large to giant forms displaying abundant, mature cytoplasm. and deeply lobulated and hyperlobulated (stag-horn like) nu- clei. The rnegakaryocytes are usually dis- persed throughout the BM but may occur in loose clusters. Bizarre, highly atypical megakaryocytes, such as those observed in PMF, are not found in ET and if present. the diagnos is of ET should be questioned 1712, 796, 2200 , 22051. Proliferation of erythroid precursors may be found in a few cases, particularly if the patient has experienced haemorrhages. but granulo- cytic proliferation is highly unusual; If present. the increase in granulopoiesis is usually only of mild degree. There is no in- crease in rnvetobtasts nor is myelodys- plasia observed, The network of reticulin fibres is normal or only minimally in- creased in ET. and the finding of signifi- cant reticulin fibrosis or any collagen fibrosis excludes the diagnosis of ET 1712, 775, 796, 2177, 2205, 22161. Bone marrow aspirate smears also reveal the markedly increased numbers of mega- karyocytes of large size with hyperlobu- tared nuclei and. in the background. large sheets of platelets. Emperipolesis of BM elements is frequently observed in ET. but is not a spec ific find ing. Stainable iron is present in the aspirated BM specimens of 40-70% of patients at diagnosis 116491. Essential thrombocythaemia 49
  • Table 2.07 WHO diagnosbc cnleria lorposl~ssenlial thrombocythaemia myelofibrosis (post·ET MF), react ive thrombocytosis, An abnormal karyotype is found in only 5-10% of pa- tients with ET when diagnosed according to lhe previous PVSG criteria {15491. There ; is no consistent abnormality. but those reported include +8, abnormalities of 9q, and del(2Oq) {939, 16821. Ahhoogh isoIatoo del(Sq) has also been reported in ET.cere- lui rrorphologic examination is required 10 distinguish such cases from MOS associ- ated with this abnormality 116821. Prognosis and predictive factors ET is an indolent disorder characterized by long symptom-free intervals, inter, ruptec by occasional ute-mreaten thromboembolic or haemorrhagic epis- odes 1705, 802, 902, 12 15, 1549, 2175 Although after many years a few pat with ET may develop 8M fibrosis associ-- ated with mye loid metaplasia (EMH such progression is uncCll'TYTlOl1 1297, 775. 1189.22201. Precise diagnostic guide- lines lor diagnosing post-Ef MF are given in Table 2.07. Strict adherence to and other WHO criteria 1143A. 21771 necessary to prevent diagnostic comus associated with early PMF accompa by thrombocytosis 1365}.Transformation~ ET to ac ute myeloid leukaemia or MOO occurs in <5% of patients, and when does occur is likely related to previous cytotoxic therapy 1705, 802, 902, 1800 Med ian survivals of 10-1 5 yea rs are common ly reported . Beca use ET usual~ occurs late in middle age. the [,Ia expectancy is near normal for man~ patients {1215. 1702 , 2200 . 2430}. Final~ it is noteworthy that the majority of clini studies are based on prev ious diag l10stic guid elines 11 549 } that fail to differentiate clearly between the early prefibrot stages of PMF with accompanying thr bocvtosrs and ET according 10 the classification 11215, 2200, 2205}. A su stannat difference in overall prognosis been reported when these two di ffer ctessmcanon systems are ap plied to same patient population 112151. Postulated ce ll of origin Haematopoetc stem cell. may initially present wittl thrombOCytosis without leukocytosis and can mimic ETcl~ ;cany.AJ1hough !he ""90 rnegaJ<ao,ocytes of ET can be easily distinguished from the small -dwarf" megakaryocytes of CML. cy- togenetic and! or rroecuer genetic analy- sis to exclude a BCR-ABL1 fusion gene is recommended for all patients in whom a di- agnosis of ET is considered 11841 1. Immunophenotype No aberrant pherotype has boon described Genetics No molecular genetic or cytogenetic ab- normality specific for ET is known. Approx- imately 40-50% of cases ca rry the JAK2 V617F or a functi ona lly similar mutation 1163. 1044,1064.1186.1 2881, Thesemu- tatoos are not specific for ETand are found in PI and PMF as well, A gain -of-Iunction mutation of MPL. MPL W515K/L , has been reported in 1% of cases of ET {16891. None of these mutations are found in cases of Additional crittril (2are~j..-cl) 1. Anaemia'« 22{1dl decrease from baselinehaemoglol*1leve1 2. Aleukoefythrobla pe~ bloodpiclufe 3. Incr&aSingsplenomegaly defiMd as &$ler an Increase in palpablesplenomegaly of>5emfrom baseIne (lislanceIrcm ltIeleft C05laI margin) orIle appearance 01 newly p.alpable splenomegaly 4. Increased LDH(atloYe reference level) 5, Development 01 >1 of3 CXlIlSlrtlllional s~ : >10% weight bss in6 month$. rightsweats, I,Il8lplBined illver{>37.5-C1 R.quired criteria 1. Documenlatiol'l of aprevklus diagnosis ofWHQ-defined essential ttlrombocythaemia 2. Bonfl marrow fibrosisgrade 2-3 (011 0-3 scale)orgrade 3-4 (oo 0-4 scale ) The lTIOfphological findings in the 8M biopsy are essential to distinguish ET from other MPN. myeloidosooes and reactive conditions that presen t with sustained ttlrcmbOCytosis, Thefinding of even a mild degree of combined granulocytic and ery- mroo proli feration should raise considera- tion of prodromal stage poIycythaemia vera (PV) 122101. and the finding of granulocytic proliferation associated with bizarre. highly atypical megakaryocytes should prom pt concern lor the prefibrotic slage of PMF 12201,22231 . Significant dyserythropoiesis or dysgranulopoiesis suggest a diagnosis of MOS rather than ET. The large mega- karyocytes with hyperlobulated nuclei of ET contrast with the medium-sized monoio- bated megakaryocytes associated with de l (Sq ) as an isolated ch romosomal abnor- mality in MDS and with the small. dysplas- tic megakaryocytes associated with the inv(3)(q21q26 2) or t(3;3)(q 21;q26.2) chro- mosomal abnormality. Lastly, some patients with chronic myelogenous leukaemia (CML) 50 MyeloproliferatIVe neoplasms
  • Chronic eosinophilic leukaemia, not otherwise specified Synonym Hypereosinophilic syndrome (not recom- mended) . can be found , and which is associated with signs of organ involvement and dys- function 1443, 23821; there is no evidence for eosinophil clonality. It is a diagnosis 01 exclusion. and may include some cases of true eosinophilic leukaemia that cannot currently be well as cases 01 cytokine-d riven eosinophilia that are due to the abnormal release of eosinophil growth factors, e.q. interleukin (IL) 2. 3 and 5, fOf unknown reasons (128, 443, 1971. 2072, 23821. Epidemiology Due 10 the previous dilficulty in distin- gu ishing CEL from idiopathic HES. the true incidence of these diseases is unknown, although they are rare. Many patients who wou ld until recently have bee n classified as having idiopathic HES can now be show n to have CEl assoc i- ated with a FJPtL 1-PDGFRA fusion gene {466 1. Since this co ndition occurs mainl y in adult men, the male dominance and the peak inc idence in the four th decade previously descr ibed in "HES" {443, 1971, 2072, 2382) are now exp lained , at least in Sites of involvement eEl is a multisystem disorder. The PB and BM are alwa ys involved. TIssue infil- tration by the eos.roonns.and release of cytokines and humoral factors from the eosinophil granules lead to tissue dam- age in a number of organs, but the heart. lungs, central nervous system, skin and gastrointestinal tract are commonly in- voiveo. Evidence of splenic and hepatic involvement is present in 30-50% of patients 1443. t971. 2072, 23821. BJ. Bain D.G. Gilliland JW , Vardiman H.-P. Horny Clinical features Sometimes eosinophilia is detected incidentally in patients who are otherwise asymptomatic . In othe r patients, constitu- tional symptoms , such as fever, fatigue , cough, angioedema . muscle pains, pruri- tus and diarrhoea are found. The most serious clinical findings relate to endomyo- cardial fibrosis. with ensu ing restrictive cardiomegaly. Scarring 01the mitralltricu- spid valves leads to valvular regurgitation and formation of intracardiac thrombi, which may embouze to the brain or else- where, Peripheral neuropathy, cen tral nervous syste m dy sfunction, pulmonary symptoms due to lung infiltration, and part. The epidemiological features of cases of HES that remain idiopathic have not vet been clearly defined. 9964/3ico-oeeee -Ctwooic eosinophilic leukaemia(CEL) is a myeloproliferative neoplasm (MPN) in which anautonomous. clonal proliferation 01 eosinophil precursors results In per- Sistently increased numbers of eosiro- ptliIs in the peripheral blood (PS), bone matrON (BM) and penooerarnssoes. with eoSKlOPh~ia being the dominant baema- k*lgical abnormality.Organ damage cc- ClSS asaresultoueceaemc infilt ration or ee releaseofcytokines, enzymes Of other proteins by the eosinoctas. Chronic eosinophilic leukaemia . not otherwise specified, (GEl. NOS) excludes patients WIth a Philadelphia (Ph) chromosome, BCR-ABL llusion geneor rearrangement 01 PDGFRA, PDGFRB orFGFR1. In eEL, NOS the eosinophil count is n5xl~1L in the blood. There are fewer than20% blasts inthe PB or 8M. To make adiagnosis 01CEl. there should be evi- dence/or clonalityof the eosiropbus or an ecreese in myeloblasts in the PB or 8M. Inmany caseshowever, it is impossible to proyeclonalrty 01 the eosooptuls. in which case, if there is no inc rease in blast cells, the diagnosis of "idiopathic hyper- eosinophilic syndrome" is made. The idiopathic hypereosinophilic syndrome (idiopathic HES) is defined as eosi no- philia(~1.5~ 1CfJ/L) persisting for at least 6 months, for which no underlying ca use Chronic eosinophilic leukaemia. not otherwise specdied 51
  • Fig. 2.31 Chronic~oop/l i l ic ~uk.aem ia . Peripheralblood smearfrom apatientWith ahistoryofpersjstenteosi1c?* Immatureaswell asmature eosinophilsarepresent CyloQenebc arlalysis showed trisomy ofchromosome 10, rheomatoroptcar findings are other fre- qu ent ma nifestations (443, 1971 , 2072, 23821 -In CEL, NOS the most striking feature in the PB is eosinophilia, there being mainly mature eosinophils with only small num- bers of eosi no philic myelocytes or promyelocytes {443. 710, 12OJ. 1971, 2072, 23821. There may be a range of eosinophil abnormalities, including sparse granulation withclear areas of cytoplasm, cytoplasmic vacuolation, nuclear hypersegmentation or hyposegmentation, and enlarged size, These changes may be seen in cases of reecuve as well as of neoplastic eosino- philia, however, and are thus not very helpful in deciding whether a case is likely to be CEl {1281. Neutrophilia often ac- compani es the eosinophilia, and some cases have monocytosis, Mild basoph ilia has been reported 17101, Blast cells may be present but are less than 20%. The BM is nvoercenotar due in part to eosinophilic proliferation 1289, 443. 710, 1200, 23821 In most cases, eosinophil maturation is orderly, without a disp ropor- tionate inc rease in myeloblasts. Charcot- l eyden crystals are often present. EryttTopoiesiS and megakaryOCytopoiesis are usually normal. The finding of in- creased numbers of myeloblasts (5-19%) supports a di agn osis of CEl, as does the ob servation of dysplastic features in other cell lineages. Mar row fibrosis IS seen in some cases 1289, 7101. Any tissue may show eosinophilic infiltration and Charcot- leyden crystals are often present. Fibro- sis is a common finding . and is caused by the degr anulation of the eosinophile with the release of eosinophil basic protein and eosinophil cationic proteins {443, 1931 ,2382}. disease 1128. 19311. In addition, a num- ber of neoplastic disorders such as t-een lym phoma, Hodgkin lymphoma, systemic mastocytosi s, acute lymphoblastic leuk· aemia and other MPN may be associated with abnormal release of Il2, 1l3, ILS or GM-CSF and a secondary eosinophilia that mimics CEll 128 , 1168, 1172, 1450, 1616. 1924, 1931,24611: in systemic mas- tocytosis there can also b e eosinophils belooging to the neoplastic clone. The BM should be carefully inspected for any process which might explain the eosino- philia as a secondary reaction, such as vasculitis, lymphoma, acute lymphoblas- tic leukaemia, systemic mastocytosis or gran ulomatous disorders. Some cases of persistent eosinophilia are due to the ab- normal release of cvtocnes by t-eensthat are immunophenotypical1y aberranl an:! that mayor may not be clonal 1286, 1156. 202 41.When such an aberran t T-cell pop. ulation is present, the case is not CEl00 is it idiopathic HES. If the monocyte con is > 1x1r:P1L a diagnosis of chronic mye;o. monocytic leukaemia with eosinoptlU may be more appropriate, but if thereare dysplastic features and> 10% neutrophl precu rsors in the PB and no rnonccytoss. a diagnosis of atypical chronic myebd leukaemia with eosinophilia should Sifn. larly be considered. The distinction between GEl. NOS. arc idiopattuc HES is important. Idiopattlc HES can be diagnosed only in fUlly inves- tigated pa tients and only when (i) there, an eosinophil count of <!:1.5x 1()l11l perse ing lor at least 6 months; (iil reaclM , e tiC ,. 1m Nc m, G. No "'";d a, • Fa lu ca wit GEl con maO as Differential diagnosis Diagnosis requ ires positiv e evidence of the leukaemic nature of the concnton and exclusion of cases of MPN with re- arrangement 01 PDGFRA. POGFRB or FGFR1. The diagnostic process often starts wi th exclusion of reactive eosino- phil ia. A detailed history, physical exami- nation, blood count and blood film are essential. Conditions to be excluded include parasitic otectoo. allergies, pul- monary d iseases such as Loetner's syn- drome. cyclical eosinophilia. skin diseases such as anqictymphoid hyperplasia, col- lagen vascular d isorders and Kimu ra's 52 Myeloproliferative neoplasms 1. There iseosinophilia(eosinophil count <!:1,5x1(ll1L) 2. Thefe isno Phchrorrosome or BCR-ABL1fusion gene or oItIer myeloproliferative neoplasms (PV. ET. PMF) orMD5ItolPN (CMULIX ICML) 3. There isnott.5;12)(q31-35.p13)«ohIr ream1l9B"*~of PDGFRB -4 There is no FlP1l1-PDGFRA fusion gene crotherrearrangement 01 PDGFRA 5, There is noI'88rrangemerltofFGFR1 5. Theblast cell count inthe peripheral blood and bone marrow isless than 20"10 and there is110 'l'(15)(p13Q22) IX1(16;16)(p13;q22) IXoIher lealureGagrlosbc ofAML 7. There is acbIaI cytol}eneIiC orrnolecaar genetic abnormaIrty, IXbIasleels aremore lhan~ in!he ~ bk:Jod«menthan 5% in !he bone marn:ow ·Ifapatient haseoiil"lOPhilia bullhese mlenaare not met!he dial;Joos4S may be reactive eosinopt1ilia,idiOpa1tMc hypereosinophiliaor idiopathichypereosinophilicsyndrome,
  • eosinophilia is excluded by appropriate h:lrcxJgh investigatoo ;(iii)AML. MPN, MOS. MPN/MDS and systemic mastocytosis are excluded; (iv) a cytokine-producmq. ~icalty-aberrant. t-een pop- ulation is excluded; (v) and there is tissue damage as a result of hypereosinophilia. Hcnteria i-iv are met but there is no tissue damage. the appropriate diagnosis is ocoamc hyperoosinophilia. Patl8rlts in whom a diagnosis of idiopathic Itypefeosinophilia or id iopalhic HES is made should be kepi under regular review since evidence may subsequently Emel'g8 that the condition is leukaemic in !'laue,Treatment may also be necessary e,tlchemstry Cytochemical stains can be used to identify eosinophils but they are not essential for diagnosis , Partial degranula- eco can lead to eosinophils having reduced peroxidase con tent. • _.-F"l9- 2.32 kiopaltiC HES.Ablood smeard a pabertWlth ca-dIaclai.n,1eukot'yt:lsi$ and~ . -No specific immunophenotypic abner- malilyhasbeen reported In CEL. Geretics No single or spec ific cytogenetic or molecular genetic abnormality has been identified in CEl. NOS. Cases with re- arrangement of PDGFRA, PDGFRB or FGFRI are specifically excluded, The detectOO d aPh cbrcroscre orBCR-ABL 1 fusion gene indicates one of the rare cases ofchronic myelogenous leukaemia wnh dominant eosinoph ilia. rather than eEL. Ellen when eosinophilia occurs in conjunction with a chromosomal abnor- mality that is usually myeloid neoplasm- associated, it may be difficult to decide whether the eosinophils are part of the clonal process. since reactive eosinophilia can occur in patients with myeloid neo-- plasms 17111. However, the linding of a recurring karyotypic abnormality that is usually observed in myeloid d isorders. such as +8 or i(17q), does support the di- agnosis of CEl 1128, 1692). Occasional pat ients have a JAK2 mutat ion 110641. x-unkeo polymorphism ana lysis of the PGK or HUMARA genes can occasionally be used in fema le patients to demonstrate cionautv 1392, 13501. Postulated cell of origin The ce ll of origin is a haemopoietic stem cel l, but the lineage potential of the affected cell may be variab le. Prognosis and predictive factors Survival is quite variable. In some series in which pat ients with idiopathic HES as well as those with probable eosinophilic leukaemia were included. 5-year survival rates approached 80% 1443. 1971,2072, 23821. Marked splenomegaly. as well as the finding of blasts in the blood or increased blasts in the 8M , cvtcqeneuc abnormalities and dysplastic features in other myeloid lineages have been re- ported to be unfavourable prognostic find ings [443, 1971. 2072 ,2382]. . Chronic eosocobtc leukaemia. not otherwise specified 53
  • Mastocytosis H,-P' Horn y' n.o. Metcalfe J.M . Bennett B,J. Bain C. Akfl L Escribaro P. Valert "AHNMO, assoc iated naematoioqrce! clonal non-mast cell disorder Fig. 2.34 Cutaneous mastocytosis, Numeroostypi:;i eac nar and maCtllop.apular pigmented eseu ct urticaria ~gmentosa ina young child" Fig. 113 Cutaoeoos maslOCytosiS. Darier"s '91- TIl skit lesions01 III bms 01 0Jtane0us II'a:Stlc)t::s ~ wI'len stroked A. palpable wileaI ~. IN moments afterhlltJysical sllrIUatIon, lkJe"hi,.. 0I1t1slamnt from !he mastcells, Fig. 2.35 Ditluseartaneous mastocytosrs. T'I'OenC. reddlSh'peau ~' 1esic:In$ d'Ia'acteI'isbc oIlilta cutaneous mastocytosis This variant ocan am:.. exdusiYely in d*'eIl 974011 9741/3 974 1/ 1 9741/3 974213 974013 9740/1 Epidemiology Mastocytosis may occur at any age Cu- taneous mastocytosis is most common in children and may be present at birth. About 50% of afflicted children develop typical skin lesions before 6 months of age . In adults. CM is less frequently diagnosed than in ch ildren 12055. 24361. A slight male predominance has been reported in CM. SM is generally diagnosed after the second decade of life; the male to female ratio has been reported to vary from 1:1 to 1:31 181, 1465, 1694). Solitary mastocytoma of skin Indolent systemic mastocytosis Systemic mastocytosis withAHNMO" Aggressive systemic mastocytosis Mast cell leukaemia Mast cell sarcoma Extracutaneous mastocytoma Synonym Mast cell disease. Sites of involvement Approximately 80% of patients with masto- cytosis have evidence of skin involvement {16871. In SM the bone marrow (BM) is al- most alwa ys involved, so morphological and molecular anal ysis of a BM biopsy specimen is strongly recommended 10 confirm or exclude the diagnosis [287. 290, 971, 12751. Rarely. the peripheral blood (PB) shows leukaemia due 10 sig- nificant numbers of circulating mast cells {972. 14841. Other organs that may be in- volved in SM inclu de the spleen. lymph nodes, liver and gastrointest inal tract mu- cosa, but any tissue may be affected 1287,966.968.973, 1275, 1334. 1466. 16941. Skin lesions occur in more than 50% of SM pat ients, and are more often observed in those with an indolent course. IC[)..() codes Cutaneous mastocytosis (urticaria pigmentosa) 9740/1 Diffuse cutaneous mastocytosis 9740/1 For the partlClpl!lms 01the Vear2lXXl Wortung Group ceeeeece on MesOCytOllS ~ flo.ooIved in the def,r1llJOIl 01 cr<terlll and WHO cIassohcllllOll 01rresto- C)'lOSIS' C Alr,1'l. KFAuslen. Jt,4 Bernett. ADBrI.roning. l Elicrlbano. H-P Horny. I( lerI'lerI.CVI.J. JB Longley, G Marone. 00 MelC8Ne. A Nunez. MA P_aresch. LB Sct>warU. I( Sollar. ~ $perl. P V8Ienl. .IN 'laid.. man. K WOlIf Table 2.09 Classification of mastocytosis. , Cutaneous mastocytosis (CM) 2, Indol&nt s)'5t&mic mastocytoSis(ISM) 3. Sy5temic mastocytosiswittl associatedclonal haematological non-mast-celliineage disease (SM·A.HNMDj 4 AggressiwSy5temic masklc)'toSis (ASM) 5, Mast cellleul<.eemia (MCl) 6. Mast c:eII sarcomlI (MCS) 7. Ertacutaneous meslocytoma Definition Mastocytosis is due to a clonal, neoplastic proliferation of mast cells thai accumulate in one or more organ systems. It is char- acterized by the presence of multilocal compact clustersor cohesiveaggregates! infiltrates of abnormal mast cells. Thedis- order is heterogeneous. ranging from skin lesions that may spontaneouslyregressto highly aggressive neoplasms associated with muttiorgan failure and short survival (Table 2.09).Subtypes of mastocytOSis are recognized mainly by the distribution of the disease and clinical manifestations. In cutaneous mastocytosis (eM), the mast cell infiltration remains confined to the skin, whereas systemic mastocytosis (SM) is characterized by involvement of at least one extracutaneous organ with or without evidence 01 skin lesions. Masto- cytosis should be strictly separated from mast cell hyperplasia or mast cell activation slates without morphological andJor m0- tecuer abnormalities that characterize the neoplastic proliferation. 54 MyeloproliferatIVe neoplasms .
  • Fig. 2.39 Systemic mastocytosis, Skeletal lesionsate common in systemicmasloc,1OSiS. This X-ray shows paldty osteosclerosis,osteoporosls WId multiple IyIiclesions mille lemur, I failure is encountered only in patients with aggressive or leukaemic disease varian ts. Significant numbers of circulating mast celts are rarely observed and are sug- gestive of mast cell leukaemia 122901. In up to 3)% of cases withSM. an associated , clonal haematological. roo-mast cellileage d isease (AHNMD) is diagnosed before. Fig. 2.36 Indolent syslelTllt mastocytosis. Dense infiltrate conSisting mainly 01 spind~ stitJ1Iy ~nUar mast eels. Fig. 2.38 Indolent systel'lic mastoeylOSis. A loo5eIy scattered spmdHhaped tlypograrlularmast cells WJlhooI tendency IIIawegate. Diagnosis islacihlatedI'fhen addibonal imrrI.rnostaHWI andmoIeaJIar analysis n performed. B IrrITlIA'lOSlain withCD25 showsanatypical ~ 01 masteels withrnentlralleassooated reactivity. infiltration of the gastrointestinal trac t by excessive numbers of abnormal mast cells P81. 1334, 22881. Haema tologica l abnormalities in 8M include anaemia, leukocytosis, blood eosinophilia (a frequent finding). neu- tropenia. and thrombocytopenia 1130, 287.713.971 , 1162, 16871. Bone ma rrow CIricaI features Cutaneous mastocytosis includes several cetrct cmco-nistocettoicqcarentities. l esions of all forms 01 CM may urticate when stroked ("Darier's sign 4 ) and most snow intraepidermal accumulation of melanin pigment. The term 'wtcana ptgmentosa 4 macroscopically describes sese two clinical features. Blistering ("b.bJs mastocytosis") does n:lI represent aseparate subtype but rather an exaq- geralion 01 urticaria. Blistering is usually seen IrIpatients lessthan 3 years of age. m may be associated with all forms of ceeoanc CM 11687, 2055, 24361. Symptoms in SM at presentation have beefl grouped into 4 categories: 1) con- SbtUtIOO8! symptoms (fatigue, weight loss, Mr,diaphoresis). 2) skin manifestations (prurituS, urticaria, dermatographism). 31mediator-related systemic events (ab- dcminal pain. gastrointestinal distress, Dushing. syncope, headache. nvpoienson. tachycardia. respiratory symptoms) and 4) musculoskeletal complaints (bone pain. oeteoceora'osteoporoers. frac tures, <JltIralgias, myalgias) {181, 22901. These symptoms range from m ild in many pabentstosevere, life-threatening mediator- related events in others, Sym ptoms may also be related to organ impairme nt (du e 10 mast cell infiltrates), pa rticularly In patients with high-grade aggress ive or eukaernic diseasevariants, Physical findings in SM at diagn osis may InClude splenomegaly (often minimal). lltile~dooopalhy and hepatomegaly are foond at significantly lower trequen- cies !966,968,973. 1275, 14661. Organo- rnegaly is often absent in the most rormon variant.indolent systemic masto- cytOSis(ISM). but is usually presen t, along w impaired organ function, in aqqres- SNesystemic mastocytosis (ASM) and in leukaemic variants. Severe systemic ~s mayocc ur in patients with ISM bbwIg eceosverelease and generatIOn rJ bcctemcar mediators including tusta- I'!'f'e.eicosanoids. poteases and heparin. For example, gastrointestinal symptoms S.d1 aspepticulcer disease Of diarrhoea n more corrmonly attributed to release rJ biologiCally active mediators than to In contrast. aggress ive variants of SM often present without skin lesion s [9711. However, some SM patients without skin escosmay on occasion present with an indolent form of SM, most often isolated 8M mastocytosis. MasfOCytosis 55
  • T~ble 2.10.Criterialorcutaneous end systemic maslocytosis S)'Itemicmastocytosis (SMI The diagnosis 01 SM CBl be made when the IIIaJOI' critenon and one IIIir'Iacriterion or at least Ihnle mnor crrteIia are prMel'll lIIajor crilerion; t.UlrfocaI,dense rliIlrates rJmast eels (::!:15mast celI$ n ~) deleded i1sections ofbone I'IllIITOW and/orOCher eltraaAaneous organ(s) Cutaneous mastocytosis (CM)" SIOO lesions demonslrebng!he typical dinicallindlng5 ofUPIMPCM. diffuse cutaneous mastocytosis orsoIttary mastocytoma, and lypiCBltlistoIogical i1filtrates 01 masl cells ina lTlJltJlocal or dlfIuse ceeem inanadequate skill biopsy. Inaddition. atiagnosbc prerequiSIte b thediagnosis ofCMistheabsence 01 features/aliena sufficiant toestablish the ~s 01 SM °l/p(laled and &I9llly modified cnteliab skin i1YO/YemerJt inmastoey!OSiS have recetlUy been suggested {<t7A}. infiltration pattern is def ined as loosely scatte red mast cells in the absence of compact aggregates. It must be noted. however, that this pattern is also observed in reactive mast cell hyperplasia and in cases of mveromastccvnc leukaemia. a term used for cases with advanced myeloid neoplasms in whom elevated numbers of immature atypical mast cess are found, but criteria for SM are not met 120651. In patients with the diffuse infiltra- tion pattern it is therefore impossible to establish the diagnosis of mastocytosis Without additional studies including the demonstration of an aberrant illYT'lUfl(} phenotype and/or detection of an acliva!· iog point mutation in KIT1977, 978 , 1196 2056,20571, In contrast, the presenced rruttifocal compact mast cell infiltrates ora diffuse-compactmast cell infiltration pattern is highly compatible with the diagnosisd mastocytosis during first inspection. H0w- ever, additional immunohistochemicala'Id molecular studies are strongly reccn- mended even in these cases. In tissuesections stained with H&E, ~ reactive mast cells usually are loosely scattered throughout the sample, and display round to oval nuclei with clumped chromatin, a low nuclear/cytoplasmic ratio. and nucleoli that are absent CI indistinct. The mast cell cytoplasm is abundant and usually filled with small faintly visible granules. Dense aggregates of mast cells are only very exceptionalfy detected in reactive states or in patere treated with stem cell factor (SCF) 11275 1694. 22901. In smear preparations, mast cells are readily visible in Romanowsky stains as med ium-sized round or oval cells with plentiful cytoplasm , containi~ densely packed metachromatic granules and round or oval nuclei. In norrnarreao tive states, mast cells are easily dislil'o guished from the smaller metactvonac Morphology The diagnosis of mastocytosis requ ires demonstration of rnultifocal clusters or cohesive aggregates/infiltrates of mast cells in an adequate 8M biopsy specimen (Table 2,10), The histolog ical pattern of the mast cell infiltrate may vary according to the tissue sampled 1130, 290 , 713, 966, 968 ,973, 1162, 14661. A diffuse interstitial is an associated clonal myeloid non-mast cell disorder, in which case this parameter is not valid. Serum tryptase levels are nor- mal to slightly elevated in most patients with CM and have also been found to be independent of the patient's tryptase haplotype 11977, 2290). simultaneously with. or after the diagno- sis of SM. In principle, any defined myeloid or lymphatic malignancy may occur as the AHNMD. but myeloid neo- plasms predominate, and chronic myelo- monocytic leukaemia (CMML) is most common 1971, 975. 2056, 2066, 2095, 22901. In patients with SM-AHNMO, clini- cal symptoms and disease course relate both to the associated baematoioqrcat dis- order and to SM 11977, 2290). Serum tryptase levels are used in the evaluation and monitoring of patients with mastocytosis, The finding of a persistently elevated serum total trypta se >20 ng/mL is suggestive of SM and is used as a "minor" criterionfor diagnosis, unless there MinorcriIW: 1. Inbiopsy sedJons rJbone nwrow orOlIlItel1raCUlaneOuS organs,:>25%ollhe mast eels r11he infihle are~ orhaveatypocaIlll(llllI1CJIog or,d aI mas! eels n bone m.arrtM'asprate smeaR, :>25% aremnalln oratypical. 2. Deleclion ofanICtiYaII'lg poI"It rnutalI:Wl at c:odor1816 of KIT~ bone manow.blocdoranolher eJ:lraCula. .........3. MastOBIs itI bone marrow.blocdoroItler eJhcutaneousorgans express CO2 and'orC025 in adl;1itlOII ~ nonnat mast011 maR-eB. <t 5enJm tolaI tryptase pet1istetllly exceeds 20l'lgIml(unless!here isanassociated daIaI myeloid dIsordar, it wtictI caselhisparamet9f 1$ not valid). Fig. 2.40 Typical skin lesion of a dIld WIlh ur1icatia pigm&nIosa. Aggregales of mast cells Iil Ihe papIIafy demIIIa'ld edllnd as 5he8ls into Ile f'8tJCWr clemis. 56 Myeloprol!ferative neoplasms
  • TIIbIt 2.11 SubdaSSlf?tiOn 01cutaneous mastocy1osis, 1. ~ pioJnenIosa (UPV~ ewneousmastoeylosis (MPCM) 2 DIuse l:lJWoeou$ mastocylO$ls 3, Sl*arI mamcytomaofskin basophils which have segmented nuclei, and larger and fewer granules. With en- zyme cytochemistry. mast cells react strongly wrth naphthol·ASD-chlofoacetate esterase (CAE) but do not express rnye!operoxidase In mastocytosis. the cylOIogy of mast cells vanes, but aboor- '!'tal cyIo1ogic features are almost always oetected.nckJdlllQ marked spindling and hypOgrarJJlarrty 122901. Cytanorpnoiogical atypia is pronounced 1'1 higtl-gfade lesions 01 mastocytosis. * ee occurrence of metachromatic eescells being a usual feature 01 mast celleukaemia 122901. The finding of tre- QUeft mastcells with bi- Of multilobated Idei rpromastocytes") usually indicates if! aggressive mast cell proliferation. aIItOJgh thesecells may be seen at low IreQuency in other subtypes of the dis- ease 122901. Mitotic figures in mast cells Ii) occur, but are infrequent even in the aggressive or leukaemic variants of SM. Kl assess mastcell numbers with cowen- lO"aISlalning procedures, Giemsa or toiu- idine blue are employed 10 detect the metachromatic mast cell granules and CAE ISalsohelpful 122901. However, the roost specitc methods lor identification of nmature or atypical mast cells in tissue sectons utilize immunohistochemical staimng fortryptase/chymase and CD117 and, for neoplastic mast ce lls. C0 2 and CD25, The morphologic features of the common subtypes of mastocytosis are tescnoeobelow. Table 2.12 Criterialorvariants01 systemicmastocytosis 1. IndolentsystemicmlStoeytosis(ISM) Meets arteria b" SM. No"C" findings (see below).Noevldence ofafl associated non.roastc:elli'leage cJonaj I1aematOOgicaI mali1laflc.yldlsonlel" (AHNMOI· In!hisvanant.!hemast cellMOefllSlowandskin lesions areaWnosI i'lVaria~ present 1.' BDnemarrow mastocytosis Asabove (ISMIwiIIlbone marrow involvement. butnoskin lesions. 1.2 Smouldering systemicmastocytosis Asabove (ISM), butwItl2 oc ITIOl'e "8' fn:l1l'lgS butno"C" ffldings. 2. Sptemie mastocytosis with n soeiBted clonal hMmaI~ norHnUt c:.Illl.... disease (SM- AHNMO) Meets CriIeria torSU and cntenaloran assoaaled.donIlIl'IIemaloklgicI flOIloITIaII eel lineage disorder. AHNMO !MOS, MPN.AJ.IL,~ . oc ott. ~ neopasm tIal meets!he alienab" a disbnd~ " tie WHO cIasslticaIm). 3. AggrlSSivt systemic: mastocylosis(ASM) Meets c:nena b SM. <noc IOOf8 "'C" Indings. Noll"o'lci8rOI ofmaslceI-..aema. UsuaIyri'1oU: sm ...... 3.1 l~hic mastocylOiIs with t<l5ioophilil Progessive ~ wCh penphefaI bloodeoswlOphIa. orten Wllh extensrve borle irlvoI'o'emeol. and tep<l~ . butusuaIyII'IIlnJI skinlesions. CasesWIltII'NI~~......m~.'" of PDGFRA weelCkJded. .t. Mastc:elileukaerrlia (MCl) Meets cnteria lorSM. Bone marrow biopsy shows a ~ lrlfiIIrabOn. usualy oompacl. byaIypicaI, immaturemast cells. Bone IT1arnllr aspirate smears snow 2O"It ormore masteels In typitaIMel. mast cells aa::ountfor10%oc more of~ blood wtIIte eels.Rarevanllfll:aleukaenK mast c:elleukaernla - asabove. but<10%ofwlile bloodcells aremastcells.Usualy wiIhouI sbl lesions 5 Mas. c:ell 5MComa (MeS) . lJfIifocaI mast celllurr'OJr. Noevidence 01 SM. Oesll'uClive growtl pattern.HiQh1lrade cytology, 6. Extl'illcutaneous mastocytoma UnilocaJ mast cell ltl'TlOU', Noevidence 01 SM. Noskin lesions. NoOOestruetiYe !1owth pattern, Low-grade --8" findings 1. Bone marrow biopsy showing >30% infinratkin bymast cells(focal, ceose aggregates) andlor serumlolal lryptase level >20 nglmL. 2. Signs ofdysplasia ormyeloproliferation. inten-mast ceil lineage(s).butinsufficient criteria fordefinitive diagnosis of a haematopoieticneoplasm(AHNMD), withnonnal oronly slightlyabnormal bloodcooors 3. Hepatomegalywithoutimpairment 01 ~v&r function, andlO!" palpatlle splenomegaly without hypersplenism, and/or lymphadenopathyonpalpalfon orimaging I "C"findings 1_ Bone marrow- dyslunction mal1lfasted byooeOf morecyOI)a!1ia (ANe <1.Ox10'1l.. Hb<10 gJdl,lX platelets <1 Clli10"Jt). butnoobvious noo-mas! ceU haematopoielic malignancy 2, Palpahla !lepatDmagalywiltlimpairment oI ~ver 1uncIlon. ascites and/orportalhyperterlSior1. 3. Skeletali1'o'Oi'o'eman1 withlarge osteolytic lesions d Ol' palhologtcallractures. .t. Palpablesplenomegaly WithhypetSJlielVsrn. S. Malabsorption WlIh we9Jl loss due 10 GImastcell infiftrates, Cutaneous mastocytosis (eM) ~dk19nosis of eM requires the demon- strahon of typical clinical findings and 'VSlOIogical proof of abnormal mast ce ll atoool the dermis (Table 2.10). In casesaisolated eM.there is no evidence ~ systemiC involvement using such oa- 1I'l"ell!fS as elevated levels of total serum ryptaSe ororganomegaly. Recently, con- snus craeria for the diagnosis of CM Il8've been further relined. and three • vanants of CM are now recogniZed 1atIIe 2111122861. Urticaria pigmentosa (UP)lmaculopapufar cutaneous mastocytosis (MPCM) This is the most lrequent form of CM. In children,1he lesions ofUP tend to be larger and papular. Histopathology typically re- veals aggregates of spindle-shaped mast cells filling the papillary dermis and ex- tending as sheets and aggregates into the reticular dermis, et ten in perivascular and penadnexar positions 124361. A sub- variant. usually occurring in young children. presents as non-pigmented. plaque-form- ing lesions. In adults. the lesions are dis- seminated, and tend 10 be red exbrown-red and macular or maculopapular. Histo- pathology of adult UP tends to reveal MastocytosiS 57
  • Rg. 2.43 A Booe marrow smear ofa patJenIWIth indolent systemiC masUytosi$. Theeel is atypical. witIlanindenled nucleus in aneccentric Iocabon, and cytoplasm ... .... an ~ emson WIt1 ~ dIslr1buIim of~ 8 Sysl8rlIc rnastlc)tlsIs. The eels may haw bland ru:lel WIIIl moderate ~ of1*tyqllasm, spinIed __ .. I'MeITtlle fibroblasts. orIctllAated nuclei WIth ab.nln dearC)'kIpIasrn TheIallereels mayresermle rnonoc:ytes orhis/ioq'Ies. and ant more oommooly seenin aggnssift "'..... Fig. 2.45 SystemiC mastocytosis, booe marrow bklpsy. AThelocal lesions01 mast cellschenconsist ofacentral core ol lymp/lOCyles, surrourldlld bypolygonal mast cells with pa~. faintly lJ"iJrlUlarcyIOplasm. WIth reactive eosinophilsat the outer margirl ol lhe lesion. 8 The lesiOns are often well-circumscribed. and may OCCIJ" irl parauabecular or perivascular Iocabons, butmay be I'lV'ldorTWy dislnbuted in the interll'abeclAar regionsaswei. • • c •c n s Cl a of s my pl. my 00< disl 0' qUE 148 'he Mastocytoma of skin This occurs as a single lesion, almost exclusively in infants. without predi lecl~ of site. The histologic picture is one ~ sheets of mature-appearing highly meta- chromatic mast cells with abundant C'/'I> plasm that densely infiltrate the oa and reticular dermis. These mast eel trates may extend into the suocoteoece tissues (11541 . Cytological atypia is na detected. This allc:M's separation 01 mas» cytoma from an extremely rare masteel sarcoma 01 the skin 119581. upper reticular dermis. In massively treted skin, the histological picture !Tll'f be the same as that seen in solitarymas» cytorna 12055, 24361. Bone marrow In most cases of SM, multifocal . sllar~ demarcated compact infiltrates 01 rna; cells are the most common and easily ce tectable feature in the BM biopsy. The infiltrates are found pred ominantly If paratrabecutar and/or perivascular loca- tions 1290, 965, 971, 977, 978. 11981.The focal lesions are comprised 01 varyiOj numbers of mast cells. intermingled w varying numbers of lymphocytes, eoere phils , tusnocytes. and fibroblasts. These diagnostic "mixed" infiltrates are o/tell w Systemicmastocytosis (SM) sa He The prerequisites for the diagnosis ofSo! di, are outlined in Table 2.10. In most cases. ex aggreg ates 01 atypical mast cells a1 era readily found in tissuesections. The crtt9'll lor variants 01SM are given in Table 2.12. fr Diffuse cutaneous mastocytosis This clinically remarkable subvanent of CM is much less frequent than UP and presents almost exclusively in childhood . Here the skin is diffusely thickened and may have a peau chagrine or peau d'a- ange (orange peel) appearance. There are no individual lesions. In patients with clin- ically less obvious infiltration 01the skin, the biopsy usually shows a band-like infiltrate 01mast celts in the papillary and fewer mast cells than observed in chil- dren. The number of lesoner mast cells may sometimes overlap with the upper range of mast cell number s found in nor- mal or inflamed skin. In some cases, examination of multiple biopsies and immunohistochemical analysis may be necessary to establi sh the diagnosis of e M 12286, 2436). 58 Myeloprol!terative neoplasms
  • Fig. 2.46 Systen'ic masb;ylosls, spleen, A Sl)Ieen tom a paletIt 'lII'i01 systen'ic maslIXylosls. BAggregates rJmast eels may be seen II tie redorwliIe pulp, orbolh. ~ his case, mast eels ate seen II apenloIi::IJNlocation. Fig. 2.43 SM-AHNUD(acutemyeloid Iel.Jkaemia). A Thestreaming,spindledeels ofa largemast eel aggregatecan be seen ononeside rJ lhebooy lrabecUkJm(arrow), weeeas a rTlCIllOIonoUs J)Opljabonofblast cellsis seen onlhlI oppositeside . BThespiodledcells of mastcell disease abut onalarge aggregale of blasts. disorders, including myeloid and especially lymphoid neoplasms, such as lympho- plasmacytic lymphoma or hairy cell leukaemia 122901. In such reactive states , the predominantly round mast cells lack major" cytological atypia. and are almost always loosely scattered throughout the tissues. a finding that clearly contrasts with the compact aggregates 01 reooiastc spindle-shaped mast cellsfound in masto- cyt osis 122901. The documentation of 8M involvemen t accompanying SM is usually established by examination 01a 8M trephine biopsy specimen. However. the analysis of mar- row aspirate smears does provi de useful should be classified according to estab- lished WHD criteria . II is important to note whether there is increased cellularity of the marrow or disturbed maturation of haematopoietic cells, because. even if criteria lora coexisting myeloid neoplasm are not completely fulfilled , hypercetlutarity Of abnormal myeloid maturation patterns cou ld be associated with an unfavourable outcome (progression to ASM or SM- AHNMD) or with a smouldenng variant of SM in which the out come is uncertain 122901. Interpretation of findi ngs must in- clude consideration that reactive, non- clonal mast cell hyperplasia may accompany a variety of haematological seen in ISM and generally show either a central core of lymphocytes surrounded bymastcells, or a central compact mast eel aggregate with a broad rim of lym- phocytes 19651· In other cases, the le- sions are mote rronorooptec and are many composed of spindle-shaped mas! cells that abut Of stream along the bonytrabeculae 1977. 9781. Significant relJCulin fibrosis and thickening of the adlacent bone are frequently Observed . ScrnetIITles. the 8M space is diffusely re- placed by compact mast cell infiltrates, which mayresemble sheets of fibroblasts 19711. Marked reticulin or even collagen fibrosis is frequentl y observed in such cases 1971, 977, 9781. Usually, there is a mixture ofboth spindle-shaped and round mastcells. Rarely, compact infiltrates may exclusively consist of round hypergr anu- 'af mas! cells, which meets the criteria for so-called trvptase-costnve round cell l'lfiltratioo 01 8M (TRDCI-8 M) 19761. In cmrest to spindle-shaped tryptase- expresSing cells that are always mast cells, the round nvptase-posmve cells in TROCI are either mast ce lls (coexpres- 9IOl'l li C0111 and chymase), neoplastic !laSl:ViIS (primary or secondary baso- It1k leoIo:aemial or myeloblasts in the of a trvotase-oosmve acute 'l'IyflIOId eokaene. CaretlJ inspection of the 8M not at!ected by mastocytosis is of crucial ecctarce. Often, the una ffected 8M is II1remarkable with a normal distribution of tal cells and haematopoenc prec ursors. Such cases usually eithe r belong to ISM o'lthinvOvemen! of skin and 8M, or repre- SMt isolated mastoc ytosis of the 8M, However, in other cases the 8M not drectly infiltrated by mast cel ls may be extremely hypercellular due to the prolif- escoof cells of non-mast cell lineages, tduding neutrophils, rnonocytes. or less frequently, eosoopbns or blast cells. De- PQ"Ong on the type of proliferating cells, eese lindlngs may be reactive (myeloid ~), or may indicate the presence dacoexistingnaematoooeuc neoplasm ll.d! as acute myeloid leukaemia, a ~ollferatiYe neoplasm, a myelodys- syndrome or myelodysplasliC/ ~ferative neoplasm, Of chronic ...""llc ~. Lymphoproliferahve diseases, such as plasma cell myeloma ~ malignant lymphoma. are less Ire- (JJllflIyseen 1110, 969, 971, 975.1 147, 1484 2056,2066, 20951. In all such cases, ~ associated naematoroorc disease e 9 ~ m I t e • Mastocytosis 59
  • granulomatoid lesions in the caranecec- ular and paratoucurar areas. or within the lymphatic follicles, or as diffuse infiltrates within the red pulp. As in other tissue sites, eosinophilia and fibrosis are fre- quently observed in areas of mast eel infiltration. In some cases. an associated haematological disorder may be present, but this is often difficult to diagnoseusirg splenic tissues alone 1973, 14661. Gastrointestinal (GI) tract mucosa Involvement 01 the GI tract mucosa bf mastocytosis is frequently suspected ctn- ically but may only rarely be assessed morphologically. As in omer tissues, • least one compact mast cell infiltrate isre- quireo to support the diagnosis of SM. IfI typical cases. these mast cells shOw an abnormal immunophenotype with expres- sion of CD25, and an activating poirt mutation of KITis present. Due to theIre- quency of CD25-positive lymphocytes. careful examination of the tissue is rec- essary to avoid false positive results.To evaluate a GI biopsy for mastocytosis, both antt-trvotase and anti-C0117 anti' bod ies should be applied in order to avoid false positive results due to strong background staining when only ant~ tryptase antibodies are used. A lew Liver Liver involvement in SM usually presen With disseminated small granulomat foci of mast cells within the periportal tracts and as loosely scattered masteels within the sousoos. Severe liver i~ rrent is only rarely seen in SM. WiderWg and fibrosis 01 periportal areas is cct- monly found. but fully developed cirrhosis is rare 1966, 14661. Spleen The white and red pulp of the spleen may be involved in SM, with rare case s show- ing preferential infiltration of the lymphoid follicles of the white pulp (9731. Here. mast cell infiltrates often present as focal have been reported 10 belong to a defined subset of ASM, namely "Iymphadeno- pathc SM with eosinophilia" 11484, 22901. In such cases, studies for rearrangement of PDGFRA are recorrmeoded, and if present, the case should be reassigned to the cat- egory of myeloid neoplasm with eosino- philia and rearrangement of PDGFRA. additional information and is crueial lor the diagnosis of mast cell leukaemia and 01 some suovanante of $M-AHNMD 122901. In ISM, most mast cells are found within the thicker regions of the aspirated crushed fragments. Mast cells in ISM, which should always be assessed in the thin regions and at a fair distance from 8M particles, usually comprise < 1% of all nucleated marrow ce lls. This is in contrast to mast cell leukaemia, where mast cell numbers by definition equal or exceed 20% of all nucleated cells in aspirate smears 1290, 977, 978, 2290}, A ...C f~ 2,49 SystemicmastlcyloliswiltIassoci8led hl*yt:ell Waerria. A Bone marrow aspi'a'B smear Wllh hairycels and al)1liCal mast eels BThe spirded mast cells M pteSel11 adjacenttothe hairyeel i'lfiItJate il lhe intersbbaI regionsoI1he ITil'I'OW Although hairycelleubemia may occasioRaIy assume a spindledlTW)IJlIlology,inIhis case lhe mast eel tryplase lustrated in (e ) dearly demonslrales !he masl eel origin 01 ltle spindled tens. alll! an imuIostaIn for C020 idenlifles ltle IIaify eels in (D). Lymph node Lymph nodes appear to be rarely in- volved in 8M in that significant lym- phadenopathy is unusual. The mast cell infiltrates within lymph nodes may involve any of the anatomical compartments but particularly involve the paraooncatareas. Mast cell infiltrates can be either focal or diffuse, but rarely totally efface preexisting architecture. Hyperplasia of germinal centres, evidence of angioneogenesis, tissueeosinophilia, plasmacytosis and reti- culin/collagen fibrosis usually accompany the mast cell infiltrates 1968. 14661. In a few patients, lymphadenopathy is marked , with a progressive clinical course mim- icking malignant lymphoma . II Significant blood eosinophilia is present. such cases 60 Myeloproliferative neoplasms
  • exceptlOl'l3l cases exhibit a diffuse com- pact infiltrationof the lamina propf"ia mu- cosae by atypical mast cells , and this 'f'B1reseroeinlIanTnatory bowel disease r:1 malignanl lymphomaat first glance. AI- klgelher, lourpatterns of involvement of theGItractmucosa by mastocytosis can be dlscnminaled 11711: 1) Loosely scat- tered mast cellswithoutdense aggregates W wrth an atypical immunophenotype and anactivating point mutation of KIT, usual~ in thesettinq 01 SM of some dura- ioo and involving the 8M, 2) Slight in- crease in loosely-scattered mast cells withoccasional dense aggregates and an atypicalrrmoopterotvce withexpression ct CD25.usually associated with an actr- ~ating point mutation of KIT, 3) Diffuse Cl:lmpaCI infillralion 01 the mucosa by atypiCal mast cells, resembling the ag- ~ive variant of SM in other tissues 1711and4)Localized mast cell sarcoma (based on one published case with in- 'OteTlerC oIlhe ascending colon) 111761. _ 1esK>ns The lfequency of bone changes varies eesubtype of disease. -'hile pure tduse ceteoscerosis is unusual in ISM Iil(:U 6%0), it is observed in about one dWl:lol patients withASM. The most com- llO'I radlOlOglcallinding associated with ISM crests of concurrent osteosclerotic andOSleolytic lesions(45%). Osteopenia Of osteoporosis is another frequent find- ing in patients with mastocytosis, and may occur in any variant. Mast eel/leukaemia (MCL) In mast cell leukaemia , mast cells equal or exceed 20% of all nuc leated cells in aspirate smears 1290 , 977, 978, 22901. In this rare and highly aggressive lorm of SM, the BM reveals a diffu se, compact infiltrate with marked redu ction of fat cells and normal haematopoietic precu rsors. The mast ce lls often show sign s of marked atypia with hypogranular cyto- plasm, irregularly shaped monocytoid or bilobated nuclei (promas tocy tes), and may even present as metach romatic blasts 122901. In some cases, the nucleoli may be prominent. In typical cases , mast cells account for 10% or more of the c irculating nucleated cells. If mast cells comprise less than 10% the circulating cens. the diagnosis of an "a'eukaem.c" variant of MCL is appropriate 122891. Mast eell sarcoma (MCS) Mast cell sarcoma is extremely rare and characterized by a localized and de- structive growth of highly atypical mast cells, which can be identified only after application 01 appropriate immunohisto- chemical markers, particularly anti-tryptase and anti-CD l17. AlthOugh initially local- ized, distant spread followed by a terminal phase resembling MCl is seen alter a short interval. Mast cell sarcomas have been reported to occur in the larynx, large bowel, meninges, bone and skin 1265, 970, 11761. Extracutaneous mastocytoma This localized tumour consists of an accumulation of mature-appearing gran- ulated strongly metachromati c mast cells, in contrast to the highly atypical mast cell s observed in a mast cell sarcoma. Extracutaneous mastocytoma is excep- tionally rare, and the reported cases involved the lung {3981. Irrm.mopheooIype Mast cells co-express COO, CD33, CD45, CD68 and CD 117 but lack several rnyelomonOCytic ant9S"S, including CD14, CD15 and CD16, as well as most T- and B-eell related antigens 1974, 977, 978, 1073, 1292, 1687, 22901, Virtually an mast cells , irrespective of stage of maturation or neoptasnc state, react with antibodies against trvptase. a cell not expressing tryptase cannot be identified as a mast cell immunohistochemically. Chymase is Mastocvtose 61
  • Fig. 2.53 Mast celleull.aem&a A ~ blood smear. Note lhe biIobed ru:tel and relatively ~ cytoplasmoften seen inItll5awessive form ofrnastIcykIIas. B Theborle marrow biopsy is li1IuseIy inIiIlr.*ldby ~slJC mastcells, CderronslriIles!he 'dear aIr appearance !hatisdue ~ !he poorgratlJIalion ofthe ltIatis typical ofinmature masteels ofmasteelleukaernia. 0 AllirmI.JnohisD::h slainbr masteel ~ """"'....... expressed in a subpopulation 01 mast cells. Chymase is highly specific but much less sensitive for the identification of atypical and immature mast cells than C0117, whereas COl17 expression is a highly sensitive but rather nonspecific marker of mast cells. Neoplastic mast cells show a similar antigen profile to that of normal mast cells, but in contrast to normal mast cells. they also coexpress C02 or C02 and C025, These latter observanons are of considerable value in the diagnosis and in the differential diag- nosis of mastocytosis and related tumours, and can be applied in immunohistochem- ical as well as in flow cytometry studies j650, 1655. 205n The application of anti- C025 enuoooree has been found particu- larly useful in the histopathological evaluation lor suspected SM. Howeve r. C02~posilive T-cellsare usually present in tissues and must be taken into account before an atypical C02-positive mast cell population can be properly identified. p.J. together, it can be assumed in the routine diagnostic evaluation 01 mastocytosis that cells expressing uvptaserctrsmase and C0117 are mast cells, and cells coax- pressing tryp tase/chymase, COl17 and C02/C025 are neoplastic mast cells 120571. C025 expression may be incon- stant or even undetectable on mast cells in some rare subvartants of the disease, such as welt-dilterentiated SM or in a sub- group 01patients with mast cell leukaemia 1141. Genetics Mastocytosis is frequently associated with somatic activating point mutations within KIT 121761. In most cases, codon 816 mutations in the tyrosine kinase domain are detectable. Rare familial cases with qecmune mutations of KIT have been reported [14,15, 1331,1332, 1333, 1557, 21761. In patients with SM-AHNMO addi- tional genetic defects are detected, depending on the type of AHNMO, Somatic point mutations of the KITprotQ- oncogene that encodes the tyrosine kinase receptor for SCF are detected as recurring abnormalities in mastocytosis 11 4,15, 1331, 1332, 1333, 1557, 1656, 21761 _ The most commonly observed mutation shows substitution 01 Val for Asp at codon B16 (D816V). This mutation results in ligand-independent activation 01 KIT tyrosine kinase and provides relative resistance to the prototypical tyrosine kinase inhibitor imatinib 1995, 15571. 62 Myeloproliferative neoplasms ..~•." ~ ~ .. e The DB16V mutation is identified in the mast cells of 95% or more of adults with SM when sensitive methods are used, in- cluding nested PNA-PCR or PCR on pooled micro-dissected single mast cells, Other activating point mutations of axon 17. such as DB16Y, D816H and 0816F are rarely seen {756. 1332, 1333, 20561. The DB16V mutation is seen in only about one third 01CM in paediatric patients 114, 1331, 1332) and the frequency of point mutations other than 08 16Vis significantly higher in CM than in SM, In patients with SM-AHNMO, add itional genetic defects may be detected, depending on the type of AHNMO. For example, in SM associated with AML, the RUNX1-RUNX1T fusion gene may be found, whereas in cases of SM associated with myeropronteratse neoplasms. JAK2 V617F may be found The detection of the FIPIL 1-PDGFRA fusion gene has been reported in patients with mast cell proliferationand eosinophilia 122861. Although patients presenting wlt'I elevated serum trvptase levels. clonal8M eosinophilia with a F/P1L1·PDGFRA fusion gene and a few scattered atypical mast cells have been described ashaving an unusual variant 01SM {130, 713,11621 most of these patients do not fulfili 8M criteria, particularly as compact mast cel infiltrates are missing, and they are best classified as a myeloid neoplasm With eosinoph ilia and rearrangement 01 PDGFRA (See Chapter 3) 122871.
  • Postulated C~II of oriQin Haematopoietic stem cells. Prognosis and predictive factors Inchildren, CM usually has a favourable outcome and may regress spontaneously before or during puberty. In adults, cuta- neous lesions generally do not regress and are. in contrast to a previous belief, oI1en associated with SM, usually the ocoient variant. One study identified predictors of a poorer prognosis as rate onset of symptoms, absence of CM. ttrembocytopenia. elevated lactate dehy- ciogenase (lOH). anaemia. 8M hypercel- k81ty. qualitative PB smear aboorrehtes. elevated alkalinephosphatase and hepato- splenomegaly. The percentage and mor- phology of mast cells in 8M smears have been identified as additional important and independent predictors of survival in mastocytosis 122901- Currently, there is no cure lor SM. and the prognosisdepends on eediseasecategory 12287, 22881. Patients with high-grade (agg ressive) disease inclUding mast cell leukaemia may survive only a few months, whereas those with indolent SM usually have a normal life expectancy 12287. 22881. SM patients with cutaneous invotvement usually also follow an indolent course, whereas patients With aggressive disease often have no skin lesions 122901 However. isolated 8M mastocytosis as a sobvanant of ISM with excellent prognosis also presents without cutaneous lesions. If there is an associated baematoroqrcet malignancy, the clinical course and prog- nosis are usually dominated by this re- lated haematological malignancy 19751_ Patients with aggressive SM generally show a rapid clinical course with a sur- vival of only a few years. MCS shows a progressive course with death within months. Patients with ASM, Mel and MCS are thus candidates lor cvto- reductive therapies. MastocytosiS 63
  • - Myeloproliferative neoplasm, unclassifiable H.M. Kvasnicka B.J. Bain J, Thiele A. Orazi H.·P. Horny JW , vardiman Epidemiology The exact incidence of MPN, U is ur*~ but some reports indicate that the pel- centage of unclassifiable cases ecccn for as many as 1~ 15% of all cases Ii MPN 1775, 2222 1, The frequency varies a number 01 other naenatopoeuc and rco-neenatcooenc neoplasms, suchas lymphoma or metastatic carcinoma, may infiltra te the marrow and cause reactive changes, inc lud ing dense fibrosis and osteosclerosis that ca n be misconstrued as an MPN 122061. Detection of a clonal cytogenetic abnormality, a JAK2V617Fa other functionally similar JAK2 mutatIOn, or an MPL IMP/.. W515K1L) rrutation distinguish an MPN from such reaclrve conditions, although not all cases ofMPN U express a currently recognized aeretc marker 12171,21771.In add ition, thedefin- ing characteristics of each MPN must be considered with the realization that, aswith any other biological process, variations00 occur, and they may progress thrt:llJ!1l different stages so that the clinical 31"(1 morphological manifestations of the dis- ease will change with time 12177, 22161 Definition The designation. myeloproliferative ne0- plasm. unctassmaore (MPN. U) should be applied only 10 cases that have definite clinical, laboratory and morphological features of an MPN but that fail 10 meel the criteria for any of the specific MPN entities, or that present with features that overlap two or more of the MPN cate- gories. Mostcases 01 MPN. U, will tall into one of three groups: 1) Early stages of poIycythaemia vera (PV), primary myelofi- brosis (PMF) or essootial thrcmbocythaemia (El) in which the charac teristic features are not vet fully developed: 2) Advanced stage MPN, in which pronounced myelo- fibrosis. osteosclerosis. or transformation to a more aggressive stage (r.e. increased blasts and/or dysplasia) obscures the underlying disorder 1775, 1216, 2206, 2216,22221: or, 3) Patients with convincing evidence of an MPN in whom a coexisting neoplastic or inflammatory disorder ob- scures some of the diagnostic clinical and/or morphological features, The pres- ence of a Philadelphia (Ph) chromosome, BCR-ABL 1fusion gene or rearrangement of POGFRA, POGFRB or FGFR 1 genes excludes the diagnosis of MPN,U. The diagnosis MPN,U should not be used wren clinical data necessary for proper classification are insufficient or not avail- able, when the bone marrow (BM) speci- men is of inadequate quality or size for accurate evaluation (1216, 22 16, 22221,or when there has bee n recent cytotoxic or growth factor therapy - problems that ac- count for the majority of the unclassifiable cases encountered in routine practice . In such cases it is often preferable to de- scribe the morphological findings, and to sug gest additional clinical and laboratory procedures that are needed to further classify the process, inCluding adequate peripheral blood (PB) and BM biopsy and aspi rate specimens. When a diagnosis of MPN, U is made, the report should sum- marize the reason for the difficulty in reaching a more specific diagnosis, and. if possible, specify which of the MPN can be excluded from consideration. If a case does not have the features of one of the well-defined entities, the pos- sibility that it is not an MPN must be strongly conside red, A reactive 8M re- sponse to infection and inflammation, lox- ins, chemotherapy, and administration 01 growth tactors. cvtokmes and irrmuno- suppressive agents may closely mimic MPN and must be excluded, Furthermore, ICD..Qcode 997513 64 Myeloproliferative neoplasms
  • I • , e , e significantly aCGording to the exper ience l1lhe diagnostician and the specific eras- sfication system and criteria utilized to dassifyMPN 11216, 22161. ElOOgy The cause is unknown. Sites 01 W1voIvement 5mlar tothe other MPN cncaJleatures r-edI1icaI features 01 MPN. Uare similar Iltoseseen in the other MPN, In pat ients ,. early, tn::lasgjfjable disease, organo- -regaly may be minimal or absent. but sclen:lmegaIy and hepatomegaly may be 'T'8SSNe i1 those with advanced d isease " "IIto'n 8M scecerees are characterized 0,~ myek)flbrosis and/or increased rurtlers of blasts 122161. The baemato- ~ vallesare also variable , and range rem mild leukocytosis and moderate to 'I'.arlo:ed thrombocytosis, with or without ~nying anaemia, to severe cvto- PfJ'8Sae 10 8Mfailure. Some patientswilt1 1IlN.Upresent WIth otherwise unexplained p:fIai or splanchnic vein thrombosis. Iil<pI<JI<lgy 'krrtcases that are diagnosed as MPN. U tJemQ to very early stage disease in iI'tlCJ the differentiation between ET, the p"elibrOlic stage of PMF, and the pre- J:dycythaemic stages of PV is difficult 11216, 2223,22241. Often, the PB smear in li.dI cases shows thromboc ytosis and Ia'iatlle neutrophilia. The haemog lobin concentration may be normal, mildly de- eeasec or borderline increased. The 8M bqJsy specimen frequently shows hyper- terlJiarityandoften prominent megakaryo- ClI'= proliferation, with variable amounts of Q'a1Jlocytic and erythroid prol iferation 12216,2223,22241, If the guidelines suq- gested in the previous sections for each specdic MPN are carefully applied with ti:lSe attention paid 10 the megakary- ocy'£ morphology and histotopography, 'lOSt cases can be accurately assigned 1I8spedic subtype; but if not. the des- ."a1OO ot MPN, U is preferable until follow-up data or adomonar lebo- 'By studies provide evidence leading 1)8 precise diagnosis. lJe-stage disease. the BM specimens -eseal dense fibrosis and/or osteo- ~, indicating a terminal or ...m<lAstage,and distinction between oost-polycylhaemic stage of PV (post-Pv MF) or rarely ET (post-ET MF) 1143A1 and lhe overt fibrotic-osteosclefotic stage of PrlAF may be impossible if there is no previous history or histology for review 12203, 22CX'i,2216, 22221· AlthoughChrc:K1ic myelogenoos leukaemia (CMl) may also be accompanied by marked myelofibro- sis, the small size of the megakaryocytes will alert the morphologist to the correct di- agnosis, and cytogenetic and molecular qenetc demonstration of the Ph chromo- some or the BCR-ABL 1 fusion gene will con firm the diagnosis of CMll775, 2216. 22221. More than 10% blasts in the PB or 8M and/or the finding of significant myelodys- plasia generally indicates a transition of the disease to a more aggressive, often terminal blast phase. If the initial diag- nostic specimen has features of a myelo- proliferative process that cannot be specifically categorized , but shows 10-19% blasts in the PB or BM, the diag· nosis of an accelerated stage of an MPN, U, is appropriate, Irrmu notlistochem- ical staining of the 8M biopsy sections for CD34 may be of diagnostic value in these cas es by demonstrating increased num- bers and/or clusters of blasts 12216, 22221. If blasts account for 20% or more of the peripheral white blood cells or nu- cleated 8 M cells in the initial specimen, then the diagnosis is acute leukaemia, and the suggestion that the case may be a blast transformation of a previous but uncl assifiable MPN is appropriate, Myelo- dysplastic features may appear during the natural progression 01 an MPN even without prior cytoreoucuve therapy. How- ever. if the initial pretreatment specimen demonstrates myelodysplasia, the diag- nosis of a myelodysplastic syndrome or of a myelodysplaslictmyeloproliferative reo- plasm, including the provisional entity, re- fractory anaemia with ring sidercblasts and thrombocytosis, should be considered 1127,1 29,865.1 245,1406.2082,2169/. Inwrunophenotype No abnormal phenotype has been re- ported for this group of patients. Genetics There is no cvtcqenetc or molecular genetic finding specific for this group. There is no Philadelphia chromosome, BCR·ABL 1fusion gene, or rearrangement of PDGFRA. PDGFRB or FGFR1. Some cases with a mutation of JAK2 as a sole genetic abnormality do not meet the cri- teria for a specific MPN or any other spe- cific disease category, and are thus best categorized as MPN, U. Postulated cell of origin Haematopoietic stem cell. Prognosis and predictive factors In patients with the initial stages of an MPN that is urctassmabie. follow-up stud- ies performed at intervals of 4-6 months wilt etten provide sufficient information for a more precise classification {2216, 2222/. Such patients in the early stages of dis- ease will have a prognosis similar to those of the group into which their disease eventually evolves. Patients with advanced disease in whom the initial process is no k>nger recognizable due to 8M fibrosis or bla stic infiltration would be expected to have a poor prognosis. Myeloproliferative neoplasm, unciasSlfiable 65
  • Myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA,PDGFRBorFGFR1 B,J. Bain D,G Gilliland H.-P. Horny JW. Vardiman Myeloid and lymphoid neoplasms with PDGFRA reanangement molecular genetic analysis or both should be carried out in all patients in whom MPN with eosinop hilia is suspected and also in pat ients presen ting with an acute leukaemia or lymphoblastic lymphoma with eosinophilia. Recognition of PDGFRA related disease usually requires molecular genetic ana lysis, since the majority of cases result from a cryptic deletion, whereas cytogenetic analysis will reveal the causative abnormality in the case of PDGFRB- and FGFR1-related disease. Definition The most common MPN associated wll1l PDGFRA rearrangement is that asSOCI- ated with F1PIL l-PDGFRA formed as a result of a cryptic deletiorl at 4q 121466l (Table 3.0 1). Presentation is generally as eEL but can be as AML, T·LBL or bon '.' .. '•. 4,,-. .,..~ "" .f ig. 3.01 FIP1L1-PDGFRA-ffllaled etvonic ~leu kaerlia. APenpheraIblood IilmstIOlWIg Ihree rrlllder*f degranulatedeosinopl'lils. Romanowsky stain. B Trephine biopsy section. Abundanl eosinophils and eosI'q)lli precursors, Giemsa stain. C Trephine biopsy S&ClIOO. Abundalll mast cells. many of wIit:tI are spindle-shaped, Iormingsmalloose dosleB, Masteel tryplIS8 staining, 0 Trephinebiopsysection.CD25expression intilemast CIk eosinophilia, Other patients have had CEL, precursor-B lym phoblastic leuka emia/ lymphoma or AML. The importance of recog nizing these dis- orders is that the aberrant tyro sine kinase activity can make the disease responsive to tyrosine kinase inhibitors, This hope has already been realized for MPN with rearrangement of PDGFRA or PDGFRB, which are responsive to ima- tin ib and some related tyrosine kinase inhibitors. Similar specific therapy has not yet been developed for FGFR 1-relaled disease. Relevant cytogenetic analysis, , • Patients preserUlg witt1 aculemyekidledaema ortyr1lJhDbIastic ~ with8CJSinOPt*l and aFIP1L1.f'OGFRA lusion geneare also aSSlgfllld tobs categoIy. ! IIappropnate OI)IeaJar.-.alysis isnot 1IYIilable.lhisliagnosis slJ:ll*S be suspected ilU1ere is. Pt-negalrve MPN lIiIlIh Ihe~ teahns ofchronic eosirq:lhIc leukaemia assooateeI WIfI~, • marked ~ of58I0OI YltaJfWI812. eIeYaliort ofserum tryplase and incteasecI bone Il'llWI'lMmast llllI!. AmyeloproIlferatMl neoplasm .",111 promnenleosmoph~ia AND Presence ofa FIPILl-PDGFRA fusion gene' T~" 3.01 Diagnosticctitena ofanMPN' wilt1 eoslnophiliaassociated witt1 FIP1U -PDGFRA. Myeloproliferative and lymphoid neoplasms associated withrearrangernenl of PDGFRA. PDGFRB and FGFA1 constitute three rare specific disease groups, which have sore shared features and some that dif- fer. All result from lormalion of a fusion gene encoding an aberrant tyrosine ki- nase. Eosinophilia is characteristic but not invariable. II has been established that, in the case 01 POGFRA and FGFRt-related neoplasms. the cell of origin is a mutated pluripotent (lymphoid-myeloid) stem cell. It is possible that this is also true for PDGFR~relaled neoplasms, but this has yet to be established. All three disorders can present as a chronic myeloproliferatIVeneoplasm (MPN), but the frequency 01manifestation as a lymphoid neoplasm varies. The clinical and neen ercoocer features are also in- fluenced by the partner gene involved . In the case of PDGFRA-related disorders, presentation is usually as chronic eosino- philic leukaemia (CEl) with promi nent involvement of the mast cell lineage and sometimes of the neutroph il lineage. l ess often, presentation is as ac ute myeloid leukaemia (AMl ) or precur sor-T lympho- blastic lymphoma (T-LBL), in both instances with accompanying eos inophilia, In the case of PDGFRB-related disease, the fea- tures of the MPN are more variable but are often those of chronic myelomonocytic leukaemia (CMML) with eosinophilia, Pro- liferation of aberrant mast cells can again be a feature. Acute transformations that have been described to date have been myeloid. In the case of FGFR r-reteteo dis- ease, a lymphomatous presentation is COOl- mon, particularly T-18L with accompanying 68 Myeloid and lymphoid neoplasms with eosinophilia and abnormalities 01 PDGFRA. PDGFRB Of FGFRI
  • Fig. 3.02 Flow diagram showingthe diagnostic process in hypereosinophilia, eEL, chronic eosinophilic leukaemia The definitivediagnosis isshownwithinblue circles/ovals, I I ~~ ------~opi ...., markedly elevated (2309).FIP1L 1-PDGFRA- associated GEL is very responsive to ima- tinib, the gene product being 100-fold more sensitive than BCR-ABl 1 1466J. MorphOlogy The most striking feature in the PB is eosinophilia. the eosinophils being mainly mature with only small numbers of eosino- phil mveiocvtes or promyelocytes. There may be a range 01 eosinophil abnormalities, inclUding sparse granulation with clear areas " cytoplasm, cytop4asmc vacuolation, smaller than normal granules , immature granules that are purplish on a Romanowsky stain. nuclear hyperseg- mentation or hyposegmentation and increased eosinophil size 1466, 23091. --_.......... @ e~ (lncludiog Hoi f _ I ...u..tI.1(11nut . . . . ~I. .... idiopathic HES --, ~". 1',......eEL_ ---_c:,.........,-=Iya&. nptIine b60CIaY Met 1n,"tiglClonb I~"!.-­,@ eel ~~~ . , t,Gr.::==:=:::'::-l gastrointestinal symptoms 1466, 1391, 23091. The majortty of patients have splenomegaly, and a minority have hepato- megaly.The most serious clinical findings relate to endomyocardial fibrosis, with en- suing restrictive cardiomyopathy. Scarring of the mitral/tricuspid valves leads to valvular regurgitation and formation of in· tracardtac thrombi, which mav emtonze. Venous thromboembolism and arterial thromboses are also observed. PulrTl()l1ary disease is restrictive and related to fibro- sis; symptoms include dyspnoea and cough; there may also be an obstructive element. Serum tryptase is increased (> 12 ng/mJ). usually to a lesser extent than in mast cell disease but with some overlap. levels of serum vitamin B12 are Etiology The cause is unknown, although several cases have been reported following cyto- toxic chemotherapy 11 625, 2157) and a case of chronic myeloid leukaemia with a BCR·PDGFRA fusion gene also followed combination chemotherapy 119061. Synonyms Chronic eosinophiliC leukaem ia: chron ic eosinophilic leukaemia wilh FIPIL1- PDGFRA; myeloproliferat ive variant of the hypereosinophilic syndrome. roo _ a The provisional code proposed for the fourth edition of IGOoO is 996513 smcuaneously (14691. Acute transforma- tion can follow presentation as GEL.Organ damage occurs as a result of leukaemic infiltration or the release of cvtokines. en- zymes or omer proteins by the eoeropnns and possibly also by mast cells. The peri- pheral blood (PB) eosinophil count is markedly elevated (in cases reported to daleithas almost always been ~ 1.5x1rPlL) atthough it should be noted that. in some series of patients. investigation was con- fined to patients with eosinophilia. There is no Ph chromosome or BCR-ABL1 fusion gene. Except when there is transformation kl acute leukaemia, there are <20% blasts fl the PBand bone marrow (8M), Epidemiology The FIP1Ll·PDGFRA syndrome is rare. It is considerably more common in men than women; the M:F ratio is - 17:1. Its peak incidence is between 25 and 55 years (median age of onset in late 40s) withreported cases ranging in age from 7 10 77 years 1131). Cinical features Patients usually present With fatigue or pruritus, or with respiratory. cardiac or Sites of involvement GEL associated with FIP1L1-PDGFRA is a multisystem disorder, The PB and 8M are always involved , Tissue infiltration by eosinophils. and release ot cv tokmes and humoral factors from the eosinophil gran- uleslead to tissue damage in a number of organs, but the heart, lungs, central and peripheral nervoussystem. skinand gastro- intestinal tract are commonly involved . The spleen is enlarged in the majority of patients. Myeloid and lymphoid neoplasms associated with POOFRA rearrangement 69
  • Fig. ] .03 Myeloid neoplasm with eosinophilia associated WIlt! PDGFRBrearrangement Penpheral blood lWn d apalienl'MIh 1(5;12) showing numerous abnoImaleosiIlOphis;eosmphis were40% cIleukoc)1eS. These chanQes may, however, be seen in cases of reactive as well as 01 neoplastic eosinophilia 11281 and, in some cases, of FIPIL I-PDGFRA·associated CEL, the eosinophil morphology is close to normal. Only a minority of patients have any increase in peripheral blast cells 123091. Neutrophils may be increased. while baso- phil and monocyte counts are usually normal 118541. Anaemia and thrombo- cytopenia are sometimes present. Any ts- sue may show eosinophilic infiltration. and Charcot-leyden crystals may be present. The 8M is hypercellular with markedly increased eosooprars and precursors. In most cases . eosinophil maturation is or- derly, without a d isproportionate increase in blasts. but in a minority the percentage of blast cell s is increased. There may be necrosis and Charoot-leyden crystals. par- ticularly in those cases where the disease is becoming more acute 14661. Bonemar- rem mast cells are often but not always in- creased on trephine biopsy 11163. 1688} and mast cell proliferation should be rec- ognized as a feature of FIP1L 1-PDGFRA- associated MPN. The mast cells may be scattered Of in loose noo-cot1esive clusters orin cohesive clus ters {1163. 16881. Many cases have a marked increase in C025+ spindle-shaped atypical mast cells , and in occasional cases morpho logical features are indistinguishable from those of systemic mastocytosis. Aeticulin is increased 111631. Patients presenting with AMl or T-l Bl have had coexisting eosinophilia(PBcounts 1 4- 172x 109/l) and in the majority of cases ore-extsunq eosinophilia was also documented (14691. Cytochemi stry Cytochemical stains are not essen tial for diagnosis. The reduced g ranule conten t of eosinophils can lead to reduced pe r- oxidase con tent and inaccurate auto- mated eosinophil counts. Immunophenotype Eosmcptulsmay show immunophenotypic evidence of activation such as expression of C023, C025 and C069 11163}. The mast cells in this syndrome are usually C02-negative cozs-coense 11162} but some times are C02-negative C025· negative 114691 and occasionally C02· positive C025-poSitive 11469J. In conp- anson, the mast cells 01 systemic masto- cytosis are almost always C025-positive and are C02-positive in about two thirds of cases. Genetics Usually cytogenetic analysis is normal, with the FIPIL I-PDGFRA fusion gene resu lting from a cryptic del(4)(q12). Occasionally there is a chromosomal rearrangement with a 4q12 breakpoint such as t(1:4Xq44:q12) 14661 or 1(4;10) (q12;p1 1) /21631. In other patients there is an unrelated cytogenetic abnormality. e.g. trisomy 8, which is likely to represent disease evolution. The fusion gene can be detected by AT-PCA, nested AT·PeR often being required 14661 The causative deletion can also be detected by fluores- cence in situ hybridization (FISH) analysis, often using a probe lor the CHIC2 gene. which is uniformly deleted, or using a break-apa rt probe that encompasses FlP tL 1and PDGFRA. Since the maiontv of patients do not have an increase of blast cells or any abnor mality on conventional cytogenetic analysis, it is usually the de- tection of the F/P 1LI-PDGFRA fusion gene that per mits the definitive d iagnosis of a myeloid neoplasm. Cytoge netic abnor- malities appear to be more common when evolution to AML has occurred (14691 Postulated cell of origin The cell of origin appears to be a pluripo- tent haemopoietic stem cell able to give rise to eosmophtts and in some patients neutrophils. rronocytes, mast cells. T cells and B cells {18541. The detection 01 the fusion gene in a lineage does not neces- sarily correlate with morphological evi- dence 01 involvement 01 that lineage. lymphocytosis. for example. is not usual, even in those with apparent involvement of the B or the T lineage 118541. In chronic phase disease, involvement is predominantly of eosinophils and to a lesser extent mast cells and neutrophils. Acute phase disease may be myelOid or T lymphoblastic 11469}. Prognosis and predictive teeters Since FIPtL 1-PDGFRA-associated GEL and its imatinib responsiveness were recognized lor the first lime only in 2003 14661. the Iong-Ierm prognosis is not yet known . However. prognosis appears favourable if cardiac damage has not already occurred and imatinib treanre« is available. lmatinib resistance can de- velop, e.g . as a result of a T6741 mutation (which is equivalent to the T3151mutation that can occur in the BCR-ABL 1 gene) 1466. 844} . Alternative tyrosine kinase inhibitors such as PKG412 and sorafenib may be effective in these patients 1468. 1297. 2103}. Patients presenting as AMl or T lymphoblastic lymphoma can achieve sustained complete molecular remission with imatinib 114691. Variants A number of possible molecular variants of F/P1L 1-PDGFRA-associated GELhave been recognized in which there are other fusion genes inco rpo rating part of PDGFRA. A male patient with imatinib- responsive CEL was found to have a K/F5B-PDGFRA fusion gene assoc iated with a complex chromosomal abnormality involving chromosomes 3. 4 and 10 11979 1. and a female patient had a CDK5RAP2-PDGFRA fusion gene associ- ated with ins(9:4)(q33:q 12Q25)123541. A male patient with t(2;4)(p24:q 12) and a STRN-PDGFRA fusion gene 14971 and another with t(4;12)(q2?3;p1?2) and an ETV6-PDGFRA fusion gene, both with the haematological featuresofCEL responded 10 low-dose imatinib 14971. Patients with t(4:22)(q12;q1 1) and a BCR-PDGFRA fusion gene, four cases a which have been described, have de- ease characteristics intermediate betweer. those of FIPIL 7-PDGFRA-associaled eosinophilic leukaemia and those a BCR-ABL t-poseve chrcnic myeIogenec:l.lS ( , E T n a "rr /: 70 Myeloid and Iymphotd neoplasms Witheosinophilia and etoomannes of PDGFRA. PDGFRB 0' FGFR 7
  • leukaemia; eosinophilia mayor may not be prominen t 1162, 765, 1906, 22661. Ac- celerated phase 11621 and T 11621 and B lymphoblastic transformation 122661 have been reported . The condition is imatinib- sensitive 11906, 2266/. Table 302 DiagnostccriteriaofMPNaSsoclatedwitll ETV5-POGFRB tusioo gene oroItIerrearrangementofPDGFRB A~~ , often -MIl ~eosilqlhIa fn:I ecreeres witt1 ~ orflUlX)'tlsis AND f'ntsence of1(5:12)(q31""Q33;pt2)ora variant translocatiOn' or,demonstrabor1 ofanETV6-PDGFRB fusion gene orofreBlfBngememofPDGFRB Myeloid neoplasms with PDGFRB roanangement , Because t(5;ll)(q3t""Q33;p12) does IIOl always INd 10 an ETV6-PDGFRB fusion gene, rnoIei::uIM conlirmation is ~ (lesjrable IfI'lJClIe(Uar ana/ySiS is not avaiable. IhisdtagnosJs shoj:j be suspected if thereISa f'Il. negative MPN asscrialed wi1tI eosirqIhiIiIlndwitha ~sIocaborl WllhI 5q31-33 brealqloint. Table 303 f.Aljecu1arvariants ofMPN associated WIth ETVU'DGFRB Modified fromIt31) aCML.alypical chronicmyeloidl6ukaemia; CEl ,chrooic eosinophilk:leukaemia:CML, chronic myeloid leukaemia: CMML,chronic myelornonotybc leukaemia: JMML,juvenile myelomonocytiC leukaemia: MPOIMOS, myeloproliferativeJmyeioctysplastic syndrome: MPN, myeloproliferative lleOpIasm. ca CMML WIth eosirloptlia aCMLWllh eosinoph6a, MPD with eosinophN eEl Pl'H'lega1ive CML(13% eoV1ophils) CMML wrlheosinophilia Ph-negabveCMLwithprominent eosinoptlIa CMML CMML JMML ca ca FUIlon V&I1t WDR48-POGFRB GPfAP1-PDGRFB TPMJ.POGFRS POE4DII'POGFRS PRKG2-PDGFRB GOtGA4-POGFRB CClJC6.PDGFRB GIT1.p()GFRB NIN.PDGFRB KlAA1S09-POGFRB TP53BP1-PDGFRB NDE1-PDGFRB RABEP1-PDGFRB SPECC1-PDGFRB t(1;3:5)(p36J)21;q33) d8r(1lll1;5)(p34:q33). dert5)1(1:5)(p34:ql5). der(11)ils(11;5Xp12:ql5q33) 1(1:5)(q21;q33) 1(1:5)(q23:q33) l(4;5;5)(q23:q31;q33) l(3;5)(pll·25;q3t-35) l(5:7)(q33;q1t.2) l(5:10l(q33:q21) t(5;ll)(q31.J3;q24) l(5;14)(q33:q24) t(5;t4)(q33;q32) 1(5;15){q33:q22) t(5:16)(q33:p1J) t(5:17)(q33:pt3) t(5;17}(q33:pl1.2) •rl _ Fig.3.04 Myeloid neoplasm wItI ~ associa1edwilhPDGFRB ~ Trephine biopsysedion In:lm a pallll'It WIth 1(5;12)showingamar1o.edincrease ineosWlclphiII. -"'ogyT!'IIS neoplasm is considerab ly more com- ~ in men (M:F.,2:1) and has a wide age range (8-72 years) with the peak rcoerce being in mi ddle-aged ad ults; reoen age of onset is in the late 405 00lS1. Syronym Chronic mvetomonocvnc leukaemia with !IOSinophilia associated with t(5;12). ICD-O code The provisional code proposed for the foorthedition of ICO-O is 996613. Definition A distinctive type of myeloid neoplasm occurs in association with rearrangement ~ PCXiFRBat 5q31-33 (Table 3.02). Usu- aIythere is t(5;12XQ31- 33;p 12) with for- malion of an ETV6-PDGFRB fusion gene 1812. 11341. In l/OCOITITlOfl variants. other "ansIocations with a 5q31-33 breakpoint lead to the formation of other fusion genes, sse incorporating part of PrX;FRB (Table 3.03). In cases with t(5 ;12) . and in the variant rransiocatcne. there is synthesis ~ anaberrant, constitutively activated ty- !OSine kinase. Thehaematological features are most often those of CMML (usually With eosinophilia) but some patients have been characterized as atypical ch ronic myeloid leukaemias (aC ML) (usually with eosinophilia), CEL and MPN with eosino- philia 1131. 20851; Single cases have been reported of AML. probably superim- posed onchronic idiopathic myelofibrosis 12245). and of juvenile myelomonoc ytic eukaemia 11513J, the latter associated /jithavariant fusion gene. Eosinophilia is usual but not invariable 120851 Acute sensiorrnaton ca n occur, often in a rela- tively short period of time. MPN with PDGFRB rearrangement is sensi tive to tyrosine kinase inhibitors such as imatinib ;64). Myeloid and lymphoid neoplasms associated W Ith PDGFRB rearrangement 71
  • Sites of involvement MPN associated with t(5;12Xq31-33;p12) is a multisystem disorder, The PB and BM are always involved, The spleen is en- larged in the majority of patients. Tissue infiltration by eosmoctats and release of cvtounes. humoral factors or granule contents by eosinophils can contribute to tissue damage in a number of organs. Clinical features Patients often have splenomegaly, with hepatomegaly being present in a minority. Some patients ha....e skin infiltration and some have cardiac damage leading to cardiac failure. Serum tryptase may be mildly or moderately elevated The great ma;ority 01 patients who have been treated with erenmo have been found to be responsive. M<Kphology The white cell count is increased. There may be anaemia and thrombocytopenia There is a ....anabre increase of neutro- phils . eosooonne. rrooocvtes and eosino- phil and neutrophil precursors. Rarely. there is a marked increase in basophils {23551. The 8M is hypercellular as a result of active granulopoiesis (neutrophilic and eosinophilic). Bonemarrow trephine biopsy may show, in addition, an increase 01mast cells and these may be spindle-shaped 1503,23551. Bone marrow reticulin may be increased 123551. In chronic phase disease, the blast cell count is less than 20% in the PB and 8M. Cytochemistry The eos inophils, neutrophile and mono - cytes show the expected cytochemical reactions for ce lls of these lineages, Immunophenotype Immunophenotypic analysis of the mast cells has shown exp ression of C02 and C025, as is also obse rved in the majori ty of cases of mast cell disease [23551. Genetics Cytogenetic analysis usually shows t(5;12) (q 31-33;p 12) with the translocation resulting in formation of an ETV6-PDGFRB fusion gene {812/ (previously known as TEL-PDGFRB), In one patient ETV6· PDGFRB resulted from a four-way trans- location, t(1;12;5;12)(p36;p 13;q33;q24) {489J, and in anomer occurred in association with ins(2;12)(p21;q?13q?22) 15121. The 5q breakpoint is sometimes assigned to 5q31 and sometimes to 5q33, although the gene map loc us of PDGFRBgene is 5q31·32. Not all translocations characterized as t(5 ;12)(q31 ;p13) lead to ETV6-PDGFRB fusion . Cases without a fusion gene are not assigned to this category of MPN and. importantly. are not likely to respond to imatinib; in such cases an alternative Ieukaemogenic mechanism is upregulation of mterleukin 3 (IL3) 14671. AT-PeA. using primers suitable for all known break- points, is therefore recommended to confirm ETV6·PDGFRB {498/ but if molecular analysis is not available a Irial of imatinib is justi fied in patients with an MPN assoc iated with 1(5;12). Postulated cel l of origin The cell of origin appea rs to be a multi- potent baemocorenc stem cell , which is able to give rise to neutrophils, monocytes. eosinophils and probably mast cells, Prognosis and predictive factors Pre-imatinib, the median survival was less than 2 yea rs, There are not yet reliab le data on survival of imatini b-treated patients, but in a small series (10 patients) the med ian survival was 65 months 15121. Med ian survival is likely to improve as patients are recognized and started on appropriate treatment at d iagnosis rather than when cardiac damage or transfor- mation has already occurred Variants A number of molecular variants of MPN with ETV6-PDGFRB fusion have been reported 1131, 20851. In addition,a patie!t who acquired eosinophilia at relapse (j AML was found to have acquired 1(5:14 (q33;q22) with a TRIPl1-PDGFRBf gene. A number of other patients ha", rearrangement of PDGFRB but With second gene involved being unl<.novo1l. Complex rearrangements appear tobe common (e.g. a small inversion as~. translocation) 120851. Because ofthe apeutic implications, FISH (break·~ FISH with a PDGFRB probe) is indicaled in all patients with a presunptive of MPN who have a 5q31-33 break particularly. but not only. if there , eosinophilia. However, FISHanalysis not always demonstrate rearrangemercd PDGFRB, even when it is detectable Southern Blot analysis 120851. MoIect.iJ analysis is not indicated if there is 5q31-33 breakpoint on classical genetic analysis since all cases re to date have had a cytogenetically de- lectable abnormality. Myeloid and lymphoid neoplasms with FGFRI abnonnalities Definition Haematoroqrce! neoplasms with FGFRJ rearrangement are heterogeneous.They are derived from a pluripotent baemaio poietic stem cell, although in differet'l patients or at different stages of thedisease the neoplastic ce lls may be precursa cells or mature ce lls. Presentation call be as an MPN or, in transformation, as AML T or 8 lineage lymphoblastic lympt'loo'lQl leukaemia or mixed phenotype acute leukaemia (MPAL) (Table 3.04). ICD-O code The provisional code proposed fOf tl"E fourth enuon of ICO-o is 996713. Table 3.04 Diagnosbc 0'ItetiaofMPNoractIIe leuk.aerria associated withFGFRf rearrangement AmyeIoproIlleralive neoplasm lMlh promIfIent eosmpI1E and sometines withneutrophilia or rTW:IAClC)'Iosi OR Acute myebd leukaemia orpreanor T<eIIorpreanor EkeIItymphoblasliC ~ {~ associated with periphetaI blood orbone JTIilITlI'W eosonophIia) AND Preseoce r:A .8;13)(P11;q12)or. v;nnlJallsb..aboil!eadlng klFGFRf~ delrorkStJaIed in ITI)'8Ioid eels, ~sts or boItl Synonyms 8p 11 myeloproliferative syndrome, 8p11 stem cell syndrome, 8p1 1 stem eel leukaemiallymphoma syndrome. EpklemKllogy This neoplasm occurs across a wide age range (3-84 years) but most patients are young. with a median age of onset iJi 72 Myeloid and lymphoid neoplasms With eosooobne and abnormalities 01 PDGFRA. PDGFRB Of FGFRI
  • around 32 years {13541. In contrast 10 MPNwith rearrangement of POGFRA and PDGFRB, there is only a moderate male predominance (1.5:1) Sites of involvement Tissues primarily involved are 8M , PB, lymph nodes, liver and spleen. lym- phadenopathy is the result of infiltration byeither Iymphoblasts or myeloid cells. Clinical features Some patients present as lymphoma with mainly lymph node involvement. while others present with myeloproliferative leatures. such as splenomegaly and hypermetabolism. and yet others wilh features of AML or myeloid sarcoma 13. 1006. 13541. Systemic symptoms such as fever. weight loss and night sweats are otten present 11311. ~ Presentation may be as CEL, AML, T-LBL or. least often. precursor B lympho- blastic leukaemiallymphoma. Cases 01 acute leukaemia/lymphoblastic lymphoma may be of mixed phenotype . In patients who present with CEL. there may be sub- sequent transformation to AML (including myeloid sarcoma), T or B lineage lympho- blastic leukaemiall ymphoma or MPAL. Lymphoblastic lymphoma appears to be rrore common in patients with t(8;13) than in those with variant transiocatons 113541. Patients who present in chronic phase usuallyhave eosinophilia and neutrophilia and, occasionally. monocyto sis. Those who present in transformation are often also found to have eosinophilia, Overall, about 90% of patients have PB Or BM eosinophilia (1354). The eosinophils be- long to the neop lastic clone, as do the Iymphoblasts and myeloblasts in cases in transformation. Basoph ilia is not usual but patients with BCR-FGFR1 fusion may have basophilia {18791. An association with polycythaemia vera has been observed in threepatients witht(6;8)1FGFRIOPI-FGFRI fusion 11770, 23401. T precursor lymphoblastrc lymphoma characteristically shows eosinophilic infiltration within the lymphoma. Cases should be classified as leukaemia! lymphoma associated with FGFR1 rearrangement, followed by further details of the specific p esenatco. e.g. "~ lymphoma associated with FGFRI rearrangement/chronic eosilophilic IelJ<ae. mia, T precursor IyrrVlobIastic lymphoma. or "leukaemia/lymphcma associated with FGFRI rearrangemenl/myeloid sarcoma". Cytochemistry Neutrophil alkaline phosphatase score is often low, but cytochemistry is not impor- tant in the diagnosis. Immunophenotype Immuno phenolypic analysis is not useful in chronic phase disease, but is important to demonstrate the T or B lineage 01 precursor Been or precursor r-ceu leukaemiallym phoma. Genetics A variety of translocations with an 8p 1t breakpoint can underli e this syndrome, Secondary cytogenetic abnormalities occur, among which trisomy 21 is most often observed. Dependi ng on the partner chromoso me, a variety of fusion gene s incorporating part of FGFR1are formed. All fusion genes encode an aberrant tyro- sine kinase (Table 3,05) Table 3.05 Chromosomal rearrangements and fusion genes reported in MPN associated wiltl FGFRt rearrangemenl·. Modrtied from (1311. Cytogeoetica M~laf geoetic:s N' 1(8;13)(pll;q12) ZNFI98-FGFR' "t(8:9Kp11;q33) CEPf1O-FGFR1 •t(6:8l(q27:pl1-12) FGFRIOP1.FGFR1 •1(822l(pl1;ql1) BCR-FGFR1 5 (l' .8l(q34:pl1) TRJN2.f.FGFRJ 1(8.11)(pl1:Q23) lrlY018A-FGFR1 1(8:19)(pl2;q13.3) HERVK-fGFR1 n(12:8)(p11;pl1p22) FGFR10P1-FGFRf • tI adclillon,FGFRJ fl!IilfTiIl'iQt!ilelt has beenku1dII iISSfJciaIio'. will ~: 12l(p11;q151aocl.8:17XP1l;q25) buth suspected IwoIYement d FGFRt 1I1(8:tl ) (p11,pt5) wasnot confrmed. I rvrtln ~ tern MaI::OoniIIdiIl"IlCross(1354). Postulated cell of orig in The cell of origin is a pluripotent tymphoid- myeloid naematopoietlc stem cell. Prognosis and predictive factors The prognosis is currently poor. There is no established tyrosine kinase inhibitor therapy for MPN with FGFRI rearrange- ment. although PKC142 was effect ive in one case 14001. Interferon has induced a cytogene tic response in several patients 11354. 14021. Until specific therapy is developed. haematopoietic stem cell transplantation should be considered. even in those who present in chronic phase. Myeloid and lymphoid neoplasms associated WIth FGFRI abnormalities 73
  • Atypical chronic myeloid leukaemia. BCR-ABL 1negative CHAPTER 4 Chronic myelomonocytic leukaemia Jwenile myelomonocytic leukaemia Myelodysplastic/Myeloproliferative Neoplasms Myelodysplasticlmyeloproliferative neoplasm. unclassifiable
  • Chronic myelomonocytic leukaemia A. Orazi J.M. Bennett U. Germing A.D. Brunning B.J. Bam J. Thiele 4 Fewer than 20%blasts" in theblood al'(j in ee bone marrow 2. No~ cf1romosomeor BCR-A8L11usion gene 3, Norearrangement ofPOOFRA orPOGFRB (sllouldbe spealicaRy e~duded 11 cases Wlth eosinophial at diagnosis is 65--75 years. with a male predominance of 1.5-3:1 148. 683. 777 2047.21021· Etiology The etiology of CMML is unknown. 0CCu- penona t and environmental carcinogens and ionizing irradiation are possible causes in some cases 1108. 20261. Sites of involvement The PB and BM are always involved. The spleen. liver. skin and lymph nodes arethe most common sites of extramedu llary leukaemic infiltration 148. 683, 777). 9945/3ICD-Ocode • Blasts irl<:IWe myeloblasts.monobIasts and prornotlOC)'le5. Promonocytes owe monocytic precursors WI1Il ab.IIdallt light grey orsIif1Iliy besophilic cytoplasmwitha lew scattered. h liIac-<::oIoIJ-ed p1UIes. finely- dislrtluled. sWied nudearetwomabn.variably prominent nudeoIi. WId delicalenud8arloIding oroeasilg.rd intIIisdassilicaliorl are equivalenl lO~. AbnormaIITIClI'IOCy1eS wnen can be present baCh ti the ~ blood and bone marrow are excluded from lhe blastCCUIIl 5. Dysplasia Inoneor more myeloid lineages. If myelodys~asia isabsent orminimal. thediagnosis ofCMM,. may still be made iflhe other requirements aremet. and' • anacquired, ctooal cylogenelic ormoleculargenetic abnoonality ispresent inthehaemopoietic cells. r:r • the monocytosis hasp&rSisted forateast 3 months and • aijother causes 0( monocytosis have been e~duded neoplasms. JAK2 V617F mutation is uo- ccmmon in CMML 11058. 20821· Epidemiology There are no reliab le incidence data for CMML. because in some epidemiological surveys CMML is grouped with chronic myeloid rewaemras and in others is rega rded as a myeioovsptasnc syndrome (MOS) 108] In one study in which CMML accounted for 31% of the cases of MOS. the incidence of MOS was estimated to be approximately 12,8 cases per 100 ()(X) persons per year (2414). The median age Definition CIvLric~ IeU<aenia (CMML) is a clonal baematopoletrc mal ignancy that is characterized by features of both a myeloproliferative neoplasm and a myelo- dysplastic syndrome. It is characterized by: 1) persistent monocytosis >1x1()9/L in the peripheral blood (PBl; 2) absence of a Philadelphia (Ph) chromosome and BCR-ABL 1fusion gene; 3) no rearrange- ment of POGFRA or PDGFRB (should be specifically excluded in cases with eosinophilia); 4) lewer than 20% blasts (promonocyles are considered as blast equivalents) in the PB and bone marrow (8M); and 5) dysplasia involving one or more myeloid lineages. However, II con- vincing myelodysplasia is not present, the diagnosis of CMML can still be made if the other requirements are mel, and an acqu ired. clonal cytogenetic ormolecular genetiC abnormality is present in the 8M cells . or if the monocytosis has persisted for at least 3 months and all other causes of monocytosis. such as the presence of malignancy, infection or inflammation, have been excluded, CMML is further subdivided into two subsets. CMML· 1 and CMML·2 , depending on the number of blasts plus promonocytes in the PB and BM. The clinical, haematological and mor- phological features of CMML are hetero- geneous, and vary along a spec trum from predom inantly myelodysplastic to mainly myeloproliferative in nature. In contrast with the BCR·ABL 1negative myeloproliferative 76 Myelodysplastic/myeloproliferative neoplasms
  • Clinical features Inthe majority of patients, the white blood cell (WBC) count is increased at the time of diagnosis. and the disease appears as an atypical myeloproliferative neoplasm. Inother patients, however, the WBCis nor- mal or slightly decreased with variable neutropenia and the disease resembles MOS. The incidence of the most common presenting complaints of fatigue, weight css. fever and night sweats is similar in re twogroups 01patients. as is the rate of otectooand of bleed ing due to thrombo- cytopenia 148, 683, 777, 2047, 21021. AI· ilough splenomegaly and hepatomegaly rn'irf be present in either group, they are morefrequent (up to 50%) in patients with leukocytosis 177n Morp/loklgy and cytochemistry Peripheral blood monocytosis is the hall- markof CMML. By definitIOn, monocytes are always >lxlQ91l and usually range from 2 to 5x10~/L, but may excee d 8Ox1()91l [48. 683, 1396, 14711. Monocytes are almost always >10% of leukocytes 189.20031. The monocytes generally are mature. with unremarkable morphology. but can exhibit abnormal granulation, or unusual nuclear lobation or chromatin pattern 111851. The tatter cells are best termed abnormal monocvtes -a desig- nation used to describe rronocvtes that are immature, but. in comparison to promonocytes (and monoblasts). have denser chromatin, nuclear convolutions and folds, and a more greyish cytoplasm, Blasts and promonocytes may also be seen , but if the sum of blasts plus the promonocytes is 20% or more, the d iag- nosis is AML rather than CMML. Other changes in the PB are variable . The wac may be normal or slightly decreased . with neutropenia, but in nearly one half of patients it is inc reased due not only to monocytosis but also to neutroph ilia (777, 1396. 16451. Neutrophil precursors (promyelocytes, myelocytes) usually ac- count for <10% of the leukocytes 1189, 20031. Dysgranulopoiesis. including neu- trophils with hypolobated or abnormally lobated nuclei or abnormal cytoplasmic granulation. is present in most cases, but may be less prominent in patients with leukocytosis than those with a normal or low wac1'185, 13961. It may be difficult in some cases to distingu ish between hypogranular neutrophils and dysplastic mooocvtes. Mild basophilia is sometimes present. Eosinophils are usually normal or slightly increased in number, but in some cases eosinophilia may be striking. CMML with eosinophilia may be diagnosed when the criteria lor CMML are present. but in addition the eosinophil count in the PB is 2:1.5xlQ1JIl. Patients in this category may have complications related to the degranulation 01 the eosinophils. These "hypereosinophilic" cases of CMML may ! f1. U 2 Chn:nc myeIomonocytic IeukaenU-l.The degree of~s, neutrr.optMia and dysploIsia isYiWiabIe .. CUt.4L. AThe ..... bIoocI eel Cl:UlliseIINaIed wiIh rnirImaI ~ in!he ~ series. B A noonaI wtJIebIoocI eel axn WIth absokJte monocytOSis. ~ and dysgrarUopoiesls. CA bone marrow biopsy splDnen Inlma ..,.. . CJM..·1. Oftsn," grarUoqIlc WI.-u"" ~ ismosl obYil::lIJs lin se biopsy ~, iW'llI monocyI8S may nol be rNliIy appreoaIed. DThe tllded ru:IeIlnl dek:aIe ....c:t'ttInRn em..... iiIic fA monocyI8S CM be appreciated IIIIO'IQ 1he~. Chrorllc myelornooocylic Ieuka8ffila 77
  • closely resemble cases of myeloid neo- plasms with eosinophilia associated with specific cytogenetiC/molec ular genetic abnormalities involving POGFRA or PDGFRB genes. for which suc h cases should always be examined . These disor- ders are con sidered separately from CMML. Mild anaemia. etten nor mocytic but sometimes mac rocytic. is common. Plateletcounts vary,butmoderate thrombi> cytopenia is often present. Atypical , large platelets may be observed 148. 13961· The BM is hypercellular in ove r 75% of cases. but rorrrccenorerand even hypo- cellular specimen s also occur (1471, 21021. Granu locytic proliferation is often the most striking finding in the BM biopsy but an increa se in erythroid precursors may be seen as well (189. 14711. M0no- cytic proliferation is invariably present. but can be difficu lt to appreciate in the biopsy oron 8M aspirate smears. Cytochemical and immunohistOChemicalstudies that aid in the identificatiOnof mcoocvtes and their less mature term s are strongly recom- mended when the diagnosis of CMML is suspected 121701· Dysqranulcpoiests. similar 10 that found in the blood. is pres- ent in the 8M of most panents with CMML. and ovsevmroooesrs (e.g. megaloblastic changes, abnormal nuclear contours. ring srderoblasts) is observed in over one half of patients 1777, 1396, 14711. Micro- megakaryocytes and/or meqekervccytes with abnormally lobated nuclei are found in up to 80% of patients [1396. 14711. I A mild to moderate increase in the amount of reticulin fibres is seen in the 8M of nearly 30% of patients with CMML 114061. Nodules composed of mature plasma- cytoid de ndritic cells (plasmacytoid monocytes) in the BM biopsy have been reported in 20% of cases 116491. These cells have round nuclei. finely dispersed chromatin, inconspicuous nucleoli and a rim of eosinop hilic cytop lasm. The cyto- plasmic membrane is usually d istinct. with we ll-defined cyto plasmic borders. This imparts a cohesive ap pearance to the infilt rating cells. Apoptonc bodies. often within starry sky testrocvtes. are frequently present. The relationship of the plasmacytoid dendritic cell proliferation 10 the leukaemic ce lls has been considered uncertain 1120, 655 , 895 , 9671. A recent study. however. has shown that they are clonal. neoplastic in nature, and closely related to the associated myeloid neo- plasm 123351. The splenic enlargement in CMML is usua lly due 10 infiltration of the red pulp by leukaemic cells. Lymphadenopathy is uncommon, but when it occurs. it may signal transformation to a more acute phase. and the lymph node may show diffuse infiltration by mye loid blasts. Sometimes, there is lymph node and (less commonly) sp lenic involvement by a diffuse infiltration of plasmacytoid dendritic cells. In some patients generalized lympha- denopathy due to tumou ral proliferations of plasmacytoid dendritic ce lls may be the presenting manifestation of CMML Blast cells plus oromonocvtes usually account for fewer than 5% of the periphera; blood leukocytes and fewer than 10%ci the nucleated BM cells at the time of d iagnosis. A higher number of blasts (plus promonocytes) than this may ident4y patients who have a poor prognosis or a greater risk of rapid transformation to acute leukaemia {48. 682, 683. 833. 2102. 2170. 24431. Thus. it is recommelldecl that CMML be furt her divided into two subcategories. dependil"lQ on the runt:lEJ of blasts (plus promonocytes) found i'l PS and 8M . as follows : CMML-1 Blasts (including promonocytes) <5% r: ee PS , <10% in the BM; CMML·2 Blasts (incl uding promonocytes) 5-1 9 in the PB or 10- 19% in the 8M . ex I'tte1 Auer rods are present irrespective of the blast plus promonocyte count. The value of this approach has been re- cently con firmed 17801. Cytochemical or immunophenotypic stud- ies are strongly recommended whenever the d iagnosis of CMML is considered When performed on P8 and 8M aspirate smears. alpha naphthyl acetate esterase or alpha naphthyl butyrate esterase, used alone or in combination with naphtt'd- ASD-chloroacetate esterase (cbioroacetae A;. 4.03 Chronic myelomonocytlc teokaemia-2. A Blood smearfrom a newly ~ patient.0C:casi0naI bl9:sls W8f1l noled.,!he perVleIaI bloodsmear. B Bilpsy~ .. same palJefW. The ImaIJ.ny of!he ba1e fllamlW BIemenIs c:ar1 be rea:iIy appreciated. CBIasts.-.d pI'Ofl'IOf'IOC) ICCOU'IC lor12".110 of!he I'fllIm)fr eels (~ ~ 78 Myelodysplasticlmyeloproliferative neoplasms
  • F"tg.4.04 Onncmyelomooocylic leukaemia, Some dl9'8801fibrosrsmay beseen inupb3O"1i 01 cases.A,8 These pl1oklmicrographs1ustra1e retiaJIin fibnls$ ina mafTllW blopsy specimen 01 a pabefIlWIIt1 CMML. is 20-40 months {48. 682, 683. 777, 779. 833,2047,2102,2170.24431_Progression to AML occurs in approximately 15-30% of cases. A number of clinical and haematological pa rameters, including splenomegaly, severity of anaemia and degree of leukocytosis, have been re- ported to be important factors in predict- ing the cou rse 01the disease. However, in virtually all studies, the percentage of PB and BM blas ts is the most important fac- tor in determining survival j48, 480, 682, 683, 777 , 780, 833, 2047, 2102 , 2170, 2443). 1 ,8 Fig, U 5 CI.-onic myelornonocytIc leukaemia ANodI.*s COfl'IPOMd 01 pIastr1ac:ybd tter'01tiC eels inthe bone R'IiIr- row 01 apatient WIIt1 CMML. Bcom is posilMIin pIasmaqtid dendriIic eels Postulated cell of origin Heerropoeuc stem cell. Prognosis and predictive factors Survival of patients with CMML is reported to vary from one to more than 100 months, but the median survival time in most series mutations of RAS genes at diagnosis or dunnq the disease course {1686, 2 118, 24171- The approp riate categorization of baematoroqrcat neoplasms associated with isolated isochromosome 17q is un- certain at this time. Although a proportion 01cases meet the criteria for CMML, others may be more appropriately categorized as MDS/MPN, uncrassmabre {708 . 14371- Abnormalities of 11q23 are uncommon in CMML, and instead suggest the diagnosis 01AML. Cases of MDS/MPN with eosinophilia associated with t(S;12)(q31 -33;p1 2) and an ETV6-PDGFRB fusion gene, which were formerly included in the CMML catego ry, are now co nside red a distinct entity, Cases resembling CMML may express the p190 BCR-ABL1 Isotorm and should be classified as ch ronic myelo- genous leukaemia (CML). Thus, if a t(9;22)(q34;q 11) is not detected by cyto- genetic analysis it is insufficient 10 use only PeA analysis for the presence of p210 to exclude CML. esterase, CAE) is extremely useful to as- sess the monocytic component. Genetics Cb'lal cytogenetic abnormalities are found in 20-40% of patients with CMML, but rmeis specific 148, 683, 684 , 777,867, 2102, 2170, 22601_ The most frequent re- :urng abnormalities include +8. -7/deI(7q) ind structural abnormalities of 12p. As many as 40% of patients exhibit point Inmunophenotype The PB and BM cells usually express the expected myelomonocytic antigens, such asCD33 and C013, with variable expres- sion of C01 4, C068 and C064 1243, 1377,24421. The PB and BM monocytes often express aberrant phenotypes with :...oar more aberrant features by flow cvto- metric analysis. Some,such as decreased expression of C014, may reflect relative rronocyte immaturlty_ Other aberrant characteristics include overexpresscn of C056, aberrant expression of C02 or cecreesec expression of HLA-OA, C0 13, C015. CD64 or C036. There may be aber- rn phenotypic features on maturing gran- ulocytic cells and neutroonas may also stlCM' aberrant scatter properties. An rceaseo percentage of CD34 + cells or an emerging blast population with aberrant .rrrnunophenotype has been associated tilth early transformation to acute eukaerma (AML) 1626. 2442 , 24591. Irrmunohistoc hemistry on tissue sec tions b the identi fication of monocytic cells is -etanvelv insensitive as compared with cytochemistry or flow cytometry. The most reliable markers are CD68R and CD l63 11649J. Lysozyme used in conjunction withcytochemistry for CAE can also faci l- ~ate the identification of monocytic cells, ...nich are lysozyme-positive but negative lorCAE, in contrast with the c renulocytrc precursor ce lls, wh ich are positive for bolh,An increased percentage of C0 34+ cells detected by immunohistochemistry has also been assoc iated with transfor- mation 116491. The plasmacytoid dendritic cells associated II'ithCMML have a characteristic immuno- peeootype. They are positive for C0 123, CD14, C0 43, C068, C068R, C0 4SAA, C033 (weakly) and CD4. Granzy me B is also regularly expresse d. but TIA1 and perforin are not. Variable C056 expression isseen in a minority of the cases, while tceu-assoctateo antigens such as C02 !'Id CDS can also be present. Chronic myeklmonocytic IeukaerTlla 79
  • Atypical chronic myeloid leukaemia, BCR-ABL1 negative JW, Vardiman J.M. Bennett B,J, Bain R D, Brunning J , Thiele Synonym . Atypical chronic myeloid leukaemia. Sites of involvement The pe riph eral blood (PB) and bone ma r- row (BM) are always invol ved: splenic and hepatic involvement are also common. Epidemiology The exact incidence of aCMl is not krlOWn, but is reported to be only 1- 2 cases for every 100 cases of BCR·ABL 1 positive CML 120031. Patients with aCMl tend to be elderly. In the few series reported to date, the med ian age at diagnosis is the seve nth or eighth decade of life but the disea se has been reported in teen ag ers as we t11266, 928, 1208, 1396,20031, The report ed maie.temare ratio varies, but based on the larger series reported , is approximately 1:1 1266 ,928, 1208,13961. Definition Atypical chronic myeloid leukaemia. BCR-ABL 1negative (aCMl) is a leukaemic disorder with myelodysplastic as well as myeloproliferative features at the lime of initial diagnosis. It is characterized by principal involvement of the neutrophil lin- eage with leukocytosis resulting from an increase 01 tnOfphologically dysplastic neutrophils and their precursors. However, mullilineage dysplasia is common and reflects the stem cell origin 01aCML. The neoplastic cells do not have a BCR·ABL 1 fusion gene. common 1189, 928,1396,20031 . The BM biopsy is hypercellular due to an increase 01 neutrophils and their pecesos Blasts may be modestly increased 111 number, but are always less than 20'%: large sheets or clusters of blasts are rICK present. Dysgranulopoiesis is a constant and the changes in the neutroptil lineage observed in the 8M are similar to those described for the blood, Megakaryo- cvtes may be decreased. normal or in- creased in number, but in most cases some oysmeqakarvopoiesrs is present including small megaka ryocytes and microrreqakarvocytes and/or megakaryo. cvteswith hypolobu laled or non-lobulated nuclei 1266, 9281. Usually the M:Eratio is greater than 10:1, but in some cases ery· throid precursors ac count for over 30%01 the 8M ce lls, Dyserythropoiesis is present in at least 50% of cases 11 89, 266, 9281_ Increased reticu lin fibres are seen in some cases at the time of diagnosis, or may counts in excess 01 3OOx1091l1266, 928, 1208, 1396 ,20031. Blasts are usually less than 5% and always less than 20% 0I1eu~ cvtes. Neutrophil precursors (promyeloc- vtes. rnveiccvtes and metamyelocytes) usually comprise 10- 20% or more of the leukocyte differential. Although the ab- solute monocyte count may be increased, the percentage of rnonocyte s rarely ex- ceeds 10. Basophilia may be observed but is not prominent 1189. 266. 928. 1396. 20031. The major feature that character- izes aC ML is ovsqranctoooese. which is often pronounced, Ac qu ired Pelger-Huat or other nuclear abnormalities, suc h as ab- normally clumped nuclear chroma tin or bizarrely segmented nuclei, and abnormal cytoplasmic granularity may be obse rved in the neutrophils. Moderate anaemi a is frequent and the red blood cells may show changes indi ca tive of dyserythropoiesis, inc luding macrcovaiocvtosrs. The platelet cou nt is variable, but thrombocytopenia is Table• •02 Dl3QOOSoc critenalor at)1Ial dlronic myeloid leuUemIa, BCR-ItBL nega!lYe (acML). ~ t*;lod Ieukocylosi$ (WBC 2:13alO'1l) cl.Ie 10IllCtlliIsed runbers 01 neutn;lp/'iIs arKI their prewrsor5 WIth prominent ~ NoPh dlromosome orBCR-ABI..1 fIlSIOIl gene NorearrMgBI'IlllI 01 PDGFRA or POGFRB Neulrophi prectJS(n {pfomyelocyles, myeIocyles,~) ~1 0% 01 leukocytes hh'naIlIbsokIIe ~ : b9soptlis USUIIy 4"4 0I1IIukocyles Ncor II'III'IirrIClI absoUe~ ; lMl'lOC)1eS <10'1t oI~ ~arbone mafTtM'wiII~ pi" . 'and ~~. W!ltl orwrtloul dysplasia nh etyflroict and megakaryocyIc Irl9Iges less than m bIiIsts n fie blood and n h bone rr8lUW 987613ICD-<l code Cl inical features There are only a lew reports of the clinical features of pa tients with aC ML. Most pa- tients have symptoms related 10 anaemia or sometimes 10 thrombocytopenia. whereas in others the chief complaint is rela ted to spleromega" 1266.928.1206. 1396.20031. Morphology and cytochemistry The white blood cell (WBC) count is always ~ 13x 1r1fL 11891 but median values ranging from 24-96x1Ql'1L have been reported and some patients have WBC 80 MyekldysplasticJrnyeloproliferative neoplasms
  • ». -,.- ~ .....Fog. ' .07Atypical chrOIlIt myeloid leukaemia. ABoneITlIITOIfI'biopsy shows 1Iypetc:eIIWnty. 0Je to~ proMerabon BNcJ(e anncrease "' Ihel1JITtler ofrnegak.afyocytes, ... smalabnonnallorms From the biopsy alone. !he fT'OlIhology wWd be dlfliQjt totjft'erentlale from BCR-ABl. po5IbYe chronic myelogenous leukaen'ia C Bone marrow . .smear. Oysplasia in!he ~ andthe megakaryo:;ybC lineages iseWlenI. appear later in the course of the disease. Most cases reported as the 'syndrome of a~mal chromatin clumping" can be considerec:l as a ....ariantof aCML 1276. 680, 10071. These are characterized in the P8 .nt 8M by a high percentage 01 reuno- :tits and precursors that exhibit exagger· eeock.mping of the nuclear chromatin . '«> specific cytochemical abnormality has been reported 10 date, although stains to detect a significant rnoncx:ytic component can be useful to exclude chronic myelo- monocytic leukaemia (CMML) . A non- SPecific esterase react ion performed on a BM aspirate may identify sign ific antly more monocytes than are apprec iated by routine stains. l eukoc yte alkaline phos- phatase scores may be low, normal or elevated. and thus are not useful for diagnosis 11208. 13961. Immunophenotype No specific immunophenotypic c harac- teristics have been reported to date, As withcytochemistry, immunohistochemical studies for CD 14 or CD68R on biopsy sections may help to identify monocytes: fnding a significant 8M monocytosis sllould call the diagn osis of aCML into coesnon. Genetics Karyotypic abnormalities are reported in up to 80% 01 patients withaCML. The most CCfTITlOlI abnormalities are +8and del(2Oq), but abnormalities of chromosomes 13, 14, 17,19 and 12 are corrvnonly reported as 'Nell 1266,928.13961. Rarely, patients whose neoplastic cells have an isolated isochro- mosome17q may have features of aCML although most will fulfill the criteria for CMML 11437f. There is no BCR·ABL 1 fusion gene. Cases with rearrangement of PDGFRA or PQGFRB genes are also specifica lly excl uded. The ac tivating JAK2 V617F mutation has been reported in some cases of aCML {1064, 12871. Approximately 30% of cases are associated with acquired mutations of NRASor KRAS123111, Some cases of t(8;9)(p22;p 24) with the PCM1..JAK2 fusio n gene have been reported as "aCML" 1259, 18331 but data cu rrently ava ilable suggest they have eosinophilia and lack myelodysplasia and may be better regarded as chronic eosino- philic leukaemia. Meticulous description of the morphology of atypical mye loid prout- erations associated with var ious geneti c defects will be necessary to assign them to appropriate categories, Postulated cell of origin Bonemarrow haematopoietic stem cell. Prognosis and predictive factors Patients with aCML fare poorly, The series reported to the present time include only small numbers of patients, but median survival times range from 14-29 months 1266, 928, 1208, 20031. Age >65 years , female sex. W8C >50x1Q91l thrombo- cytopenia, and Hb <10g1dL have been reported to be adverse prognostic find- ings {266. 9281. However, patients who receive 8M nansptantanon may have an improved outcome 111781. In approximately 15-40% of patients, aCML evolves to acute myeloid leukaemia. wherea s the remainder die of marrow failure {266. 12081, AtypIcal crvooc myeloid leukaemia. BCR-ABL 1reqanve 81
  • Juvenile myelomonocytic leukaemia I Baumann J,M. Bennett C.M. Niemeyer J , Thiele K, Shannon Table 4.03 Diagoosticarteria of juveoilemyelomonocyticleukaemia" "McOfled from 11596}. ."InIIliScialslkalJon. protI'I(lllCICy In equivaIer( 10 bIa5ts. - • •• •.. • .~ • 1 •<) • •FIg.4.111 ..hJyrie myek:m:lnocytlc IUaeITia I.MU PenpheraI blood smeal" shoWn;l abnornIaI ~ wotrl C)t:IpIasmic vacuolesand two oormoblasl5. have lymphadenopathy. In addition , W- aemic infiltrates may give rise to markedy enlarged tonsils. Signs of bleeding are frequent and about a quarter ofthe caress have skin rashes. Cafe au tait spots are noted in patients with NFl . A remarkable feature of many JMML cases is a ma rke dly increased synthesis 01 haemoglobin F, specifically in cases WIth a normal karyotype 1345. 15951. AddrtiClrl! features include polyclonal hyp ergamma- globulinaemia and the presenc e of auto- antibodies 1345, 15951. The cl inical and laboratory features of JMML sometimes closely mimic infectious diseases, including those due to Epstein-Barr virus, cytomega- loviru s, human herpesvirus 6 and others 11 376, 1596, 17511, Appropriate laboraicv testing including mo lecu lar studies and if1 vitrocultures may be requ ired to exclude infec tions as a cause for the clinical arc haematoroqc find ings In vitro, there is marked hypersensitivityol myeloid progenitor cells to GM-CSF 16441; this has become the hallmark ofthe disease and represents an important diagnostic lo:t Morphology and cytochemistry The PB is the most important specimen III proving the diagnosis. It generally stoes leukocytosis, throm bocytopenia and oae- anaemia1345.1346. 15951. Themedianre- ported .....tIile blood count ('NBC) varies lrcm 25-30x1Ql1Il, but rarely is >l00xll1i. The leukocytosis is comprised mainly aI neutroohns. with some immature ceus such as promyelocytes and mveocytes. Clinical features Most patients present with constitutional sym ptoms or evidence of infection 345, 1346, 1595l. There is generally ma rked hepatosplenomegaly, Occasionally spleen size is no rmal at diagn osis but rap idly increases thereafter, About half the patients Sites of involvement The PB and BM always show evidence of myerononccvnc proliferation. Leukaemic infiltration of the liver and spleen is found in virtually all cases, Although any tissue may be infilt rated, lymph node, skin and the respiratory tract are other co mmon sites of involvement 1345, 1346, 15951. Etiology The cause of JMML is not known. Rare cases have been reported in identical twins 17051. Theassociation between NF1 and JMML has long been established 1345. 1595, 21011. In contrast to adults who have NFl . children with NFl are reported to have a 2OQ. to 5(X).fold increased risk of developing myeloid malignancy, mainly JMML 115951.Occasionally young infants withNoonan syndrome develop aJMML-like disorder, which resolves without treatment in some cases and behaves more aggres- sively in others 11211, These children carry germhne motanons in PTPN11,lt1e gene encocting the protein tyrosine phosphatase SHP2121621 or in KRAS119741. 994613ICD-Ocode 1. F'eflpheralblood ~ >b lO'IL 2. Blasts (ird.Jdlng ~)" In <:!(l%oflie leUor.ocyles IIeeblood 1Rlof!hermeated beneITI8ITtlW eels 3 NoPh dlomosome or BCR-ABL1fusion gene .4 Plus two ex moredille loIowing: - HaemogIoI:lln F irocrea&ed lorage - Irm'Iature granulocyles intheperipheralblood - WBC counl>10J;10"/l • Clonal d1I01TC1SOm111 abrlormIldy (maybemonosomy 7) • GM.csF hyper'5enIIbviI ofmyeIold progerIIIor5 on I'itro Definition Juvenilemyel:m:>nocyt<; ""-'<aemia (JMMLI is a clonal haematoocietrc disorder of childhood characterized by proliferation princi pally of the granulocytic and m0no- cytic lineages. Blasts pius promonocytes account for <20% of cells in peripheral blood (PB) and bone marrow (8M). Ery- throid and megakaryocytic abnomaunes are frequently present 132. 303, 14771. BCR·A8L , is absent, whereas rrctato-s in- volving genes althe RASIMAPK pathway are characteristic. Epidemiology The inci dence of JMMl is estimated to be approximately 1.3 per million children 0- 14 years of age per year. It accounts for less than 2-3 % of altleukaemias in children, but for 20-30% of all cases 01 myelodysplaslic and myeloproliferative disease in patients <14 yearsof age 1907. 17041. The age at diagnosis ranges from one month to early adolescence, but 75% of cases occur in children <3 years of age 1345, 1346, 15951, Boys are affected nearly twice as freque ntly as g irls, Approxi- mat ely 10% of cases occur in children with the clinical diagnosis of neurofibro- matosis type 1 (NFl) 1345 , 1595,210 11. 82 Myelodysplastic/myeloproliferative neoplasms
  • Genetics Karyotyping studies show monosomy 7 in about 25% of patients, other abnormali- ties in 10%. and a normal karyotype in 65% 115951. Philadephia chromosorneand the BCR-ABL I fusion gene are absent. Fig. •U t JuvenilemyeIomooocytlc leukaemia, AThe bone marrow-aspole&IM3f usuaty refIecls thedafIge$ noted intheblood. buI!he monocyle ~ lllIlI is dmft10 appreciate, 8 ACOlTiw'oed alpha naplhyI acela1e eslefase and naptl~ esterase'eaclion idenblies the vanulocytlt (bluereaction product)andthe ITIOflOCYlIC component (brown feacbon product).Aleweels containbolhpnxIuct$ • Fig. 4.10 Juvenile ~ lOCytJc leukaemia, A The b<:Jre marrow is ~ wrlhg~pn:lilefabon. B The megakalyocytes are reduced in IlUfTlbef, but appear rTlOIphologlcally IlOffIIII in Ihe biopsy Blasts arenot substantially ineteased inrvnber. foC~ *Fig.4.11 JU'.'OOilernyeIofnoncq1ic leukaemia. The leukae ~ infiltrate inthe Iivef isinthe portalregiOns (AIasweias in!he hepalicsinusoids (8) , C The leukaemicI1filtralein!he redpulpof!he spleen encroadles ~ !he gemiIIaI ten. Int. 0 The infiltJale is compfised mainly ofimmalufltandmaluflt neutrophils and fTIOflOCYes. is best detected by irTVTlunohistochemica l techni ques that detect lysozyme and CD68 R. However, individual cases may show almost excluswetv infiltration by myeloperox idase-positive granulopoietic precursor cells. - type"'speo!ic ~abroonaJ'" rave been reported in JMML. In extra- ~ 1JSSUeS, the monocytic COflXIl8llI as well as of roonocytes. Blasts (including promonocytes) usually account for fewer than5% of the white cells, and always less than 20%. Eosinophilia and basophilia are ooseved in a minority of cases, Nucleated red blood cells are often seen . Red blood cell changes include macrocytosis, partie- ulartyin patients with monosomy 7, but nor- mcx:ytic red cells are more common, and recrocvtosrs due to iron deficiency or ac- QOired thalassaemia phenotype 1961} may be seen as well Although platelet counts arevariable, thrombocytopenia is usual and may be severe 1345, 1346, 1595, 17051. Bone mar row findings are not by them- selves diagnostic. The 8M aspirate and biopsy are hyperceUularwith gral'lUloCytic proliferation , although in some patients erythfoid precursors may predominate 1595, 17051. Monoc:ytes in the BM are often less impressive than in the PB. generally accounting lor 5-10% 01 the BM cells. Blasts (including prorooo- cytesj account tor <20% 01the 8M cells. andAuer rod s are never seen . Most often dysplasia is minimal. However, dysgranu- ccorese. including pseudO Pelqer-Heet neutrophils or hyp:>granularlty may be noIed n somecases and erythroid precursors may be enlarged, Megakaryocytes are cnen reduced in number, but marked rregakaryocytic dysplasia is unusual 1345, 1595, 17051. Reticulin fibrosis has been noted in some patients 13451. Leukaemic infiltrates are common in the skin where myelomonocyt ic celts infiltrate the superficial and deep dermis, In the IUl"Ig, leukaemic cells spread from the cap- illaries of the alveolar septa into alveolae. ¥ld il"l the spleen they infiltrate the red pulp, and have a predilection for trab ecular and central arteries, In the liver, the sinusoids eoo the portal tracts are infiltrated , ~ specific cvtocterracaiabnormalitieshave been reported in JMML. In 8M aspirate smears. cytoc hemical stains for alpha naphthyl acet ate esterase Of butyrate esterase, alone or in combination with naphthol-ASD-chloroacetate esterase, may be helpful in detection of the mono- cytic component. Although leu kocyte all.aline phosphatase scores are reported to be elevated in about 50% 01 patients, this test is not helpful in establishing the diagnosis 113461. JlIVenile myebnonocytic leukaemia 83
  • I EttK tor Pathways Neurofibforrin effect plays an important role, since a substantial proportion of children can be cured alter a failed HSCT by donor 1ym- phocvte infusion and immunomodulatory therapy 117871.The role of anti-leukaemic eeaov prior to HSCT is currentlyu-ceten PTPNU Mutation (-35%) GM~SFR GM~SF Ra s -GDP I G, b2 SO~ ~---.......r-, She Gab2! ~ .-I SHP-2 - - "..,""'"""~ Fig.4.12 Molecular lesions ~ Ras sir¥'*'!l prOWlS in JMM.. GM-CSf normaIy binds kI its rec:epD". in1al I'IeterIXlin1er ¥d asserrbIes 8 ~. d S9'*9 mclIo.JIes a'ldadaplets flat i'le1.I::les She: and GttI. ThesI proieln$. " un. ftICI"Uit Gab2. SHP-2and 505. 1IltliCh eataIyzeI~ IWJd80lIde ~ lllI Rasand iwnases irr.IoeI.D"leYeIs d Ras-GTP. oeeaetvaaed, Ras-GTP~ ..... arurtJerd ~ elfectIrs, The Gw. lIdMIlogproB1s pt2OGN' and net.6OIibn:mn brld kIRas-GTP and aoc:eIerate lXlfI'o'eIWn d Ras-GTP kIRas-W' ~ kIGM-CSf is a ceIlW haImart. d JtAt. ltIal resullsfrom a rurtJer d lisln::l genetic ~ t.lJtaIioI1s inPTPNfl increaseSHP·2phosphatase acIYlty a'lderNIce Ras SigrlafrIg. SiTI1arIy.cancer-associaled... acid Slbsl.iluIiCI'I inNRAS orKRAS2 red in/TJJlarIl: Rasprol8in:s IIaIlICO.Il1Jiate " ee acINe. GTP-b:u1d c:onbma- lion.FnaIy. inacIivaIiorI ofllleNFl ~ ~gene ~ Rassigoahng ItlrtXJgh loss ofneurofib'orm die from organ failure. such as respiratory failure. due to leukaemic infiltration. Haernatcpoietic stem cell transplant (HSCT) from a related or unrelated HLA com patible donor can cure about half the patients 113261. Relapse is the major cause of treatment failure, There is clea r evidence that graft versus leukaemia Prognosis and predictive factors Although JMMl rarely transforms into acute leukaemia. it is a rapidly fatal disor- der for most children If lelt untreated . The median survival time Without allogeneic stem cell transplantation (HSCT) is about one year. Low platelet count, age above 2 years at diagnosis and high haemoglobin F at diagnosis are the main predictors of short survival 1345. 1595. 17051. In the ab- sence of effective treatment, most children Postulated cell of origin Haematopoietic stem cell. There is evidence that JMML is, at least in part. due to aberrant signal transduction resulting from mutations of components of the AAS/MAPK signaling pathway, So- matic mutations in PTPN 11occur in 35% of patients 11329, 21621. and oncogenic mutation of the RA$ genes, NRAS and KRAS2, and of NFl are each seen in ap- proximately 20% 121621. Mutations in PTPN1', the RAS genes and NFl are largely mutually exclusive, suggesting that pathOlogical activation of AAS de- pendent pathways plays a central role in the pathophysiology of the disease. In JMML cells of children with NF 1, unr- parenteral dlsomy results in dUplication of the mutant NFJ allele 1714, 20961. Since the NFt gene product, a negative rroourato- 01 AAS function, the lossof the normal NFt allele is associated with AAS hyperactivity 119971, •s ( 1 s ti C T o •2 84 MyelOdysplasticJmyeloprolilerative neoplasms
  • Myelodysplastic/myeloproliferative neoplasm, unclassifiable JW. Vardiman J.M . Bennett B.J, Bam I. Baumann J , Thiele A. Orazt Synonyms lIXedmyelocrouterawe/myelocysptastc syndrome, unctasstnebre: "overlap" syn- acme, unclassiliable . &las of involvement The BM and PB are always involved: spleen, liver and other extramedullary ':ISSUeS may be involved. ~icaI features The clinical features of MDSlMPN, U OYerlap those found in diseases of the l.tOS and MPN categories 1129. 1588. 23111. Postulated cell of origin Haematccoretrc stem cell. Genetics There is nocvtooeoetc or rooIecular genetic finding specific torthis group.A Philadelphia chromosome and BCR-ABL1fusion gene should atways be excluded prior to making the diagnosis of MDSlMPN, U. Cases with rearrangements of POGFRA, PDGFRB or FGFRI or with isolated del(5q) or 1(3:3) (q2 1:q26) or inv(3Xq21q26) are excluded from this category as well. In difficult cases. the presence of a JAK2 V617F mu tation may help to confirm a haemato- poietic neoplasm. thoug h the significance of such mutations in this entity is uncertain. Occasional cases with isolated del(5q) and JAK2 V617F mutation have been re- ported to have features that overlap MDS and MPN 110051. Refractory anaemia with ring sideroblasts (RARS) associated with marked thrombocytosis Definition Inthe thirdeditionofthe INHO Ciasetcaton RAR$-T, previously also referred 10 as essentia l thrombocythaemia (ET) with ring sioerobiasts. was proposed as a provi- siona l entity to encompass patients who have the cuncat and morphological fea- tures of the myelodysplastic syndrome, The case has dirucaI, laboratory and ~ IN!ufes rJonerJ!he ca1egories rJMDS (reifacklry ~ WIItl unineage: dysplaSIa, relraalryaJla&mia WIIlI'IIgSiCIerObIasIs. reIracIory tyqlenia 'MIhIlUb- Iileage ~. relradory anaemia -.ilh elC8SS 01 blasts) and <20"4 blasts in the blood and bone marrow ""HasproITWlenI mye!oploilelalMlleatLres,e.g. pIMeleIaut a 45OJ;10'lt associaIed -.ilh megakaryotytlc proIileration, orWBC COld~1 h1l1'lt, MIh orWI1hOul P'tJn*Ienl spIeIlllfTIllgaIy ""tia$ no preceding tGlfy rJIn ~ W'N orrJKlS,nohlst:lryrJn!CeflI L)'k*JXlC or~ Iador hel'apy ~ ccokle.'(j)lain !he ~ or1ll)eIopi00000llti.. feaUes , IIfId noF'hiadelphia chCfl'CSOlII8« BCR-ABL1 k.tsion 98"8, no realral'9lll,.ltrJ PDGFRA. PDGFRB orFGFRf,1IfId no isolated del(5q},l(3:3)(Q2I;(l26) or1fI'l'(3)(Q21q26) The palienlhas de rICM) disease WItl nned myeIoprolilnlrt'8 and myelodyspIastIc features IIfId eatnlt beassigned toi1It'/ olhercategory rJMOS, MPN«rJMDSIMPN. Morphology and cytochemistry These disorders are characterized by pro- liferation of one or more myeloid lineages that is ineffective, dysplastic or both and simultaneously, by effective proliferation . with or without dysplasia, in one or more of the other myeloid lineages, l aboratory features usually include anaemia ofvariable severity, with or without macrocytosis and ofte n dimorphic red blood cells on the peripheral smear. In addition, there is evi- dence of effec tive proliferation in one or more lineages, either as thrombocytosis (platelet count ~ 45Ox1Q91l) or leukocytos is (white blood cell count ~1 3x 1 09/l) , Neu- troph ils may show dysplastic features and there may be giant or hypogranular platelets, Blasts account for <20% of the leukocytes in the PB and of the nucleated cells of the BM, and a finding of >10% blasts in the PB or BM likely indicates tranetoenetoo to a more agg ressive staqe. The 8M biopsy specimen is hypercellular and may show proliferation in any or all of the myeloid lineages. However, dysplastic features are simultaneously present in et least one cell line. Cytochemical findings may be similar to lhose seen in MDS or in MPN, IrrmJnophenotype May be similar to findings in MDS and/or MPN. 9975/3ICD-O code Definition Myelodysplastic/myeloprohferative neo- pIasm. lI'lClassifiabie. (MDWPN. U)meets !he criteria lor the MDSIMPN category in lhat, at the time of irntial presentation , eee are clinical, laboralOf'y and rrcepro- bgicaI features that overlap both MOO and MPN. Cases classified as MDS/MPN, U 00 not meet the criteria lor chronic myelomooocytic leukaemia . juvenile myelomonocytic leukaemia or atypical d'rlnc myeloid leukaemia Thefinding 01 a oc:R-ABL , fusion gene or of rearrangement 11 PDGFRA, POGFRB or FGFR' excludes tie diagnosis of MDSlMPN, U. It is important that the designation UDSnvtPN, U not be used for patients with aprevious, well-defined MPN who develop Oysplastic features in association with eans'ormeton 10 a more aggressive rrase. HoNever, MD5'MPN, Umay include sere patients in whom the chronic phase 01 an MPN was not previously detected. :rld who initially present in Iransformalion MIh myelodysplasticfeatures. If the under- ~ MPNcannot be identified. the desig- ration of MDS/MPN, U is appropriate. If there has bee n any recent cytotoxic or arowth factor therapy, follow-up clinical and laboratory observations are essential kldemonstrate that the peripheral blood (PS) and bone marrow (BM) changes are 'lOt due to the treatment. MyelodysplasticJmyeloproliferative neoplasm, uoclassifiable 85
  • Morphology These cases have features of AAAS (anaemia With no blasts in the PB and dysplastic , ineffective erythroid prolif8fation often with megaloblastoid features, ring sideroorasts :2:-15% 01 the erythroid pre- cursors. and <5% blasts in the BM) and thrombocytosis With a platelet count :2:-450x1CJ1Il associated with proliferation AARS, bul who also have marked throm- bocytosis assoc iated with abnormal megakaryocytes similar to those observed in the BCR-ABL 1nega tive MPN, such as ET or eartv-staqe primary myelofibrosis (PMF) 1865,1077,21091. However, some investigators have suggested that MAS-T is not a unique entity but instead repre- sents cases of other subtypes of MDS or well-defined MPN that have acquired ring sidercbtasts as a secondary form of dysplasia 119661. It is not clear whether AAAS-T is a distinct entity, one end of the spectrum of AAAS. a progression of AAAS due to an addrtiooat acquired genetic abnormality. or less likely. Ihe occurrence of two rare diseases in the same patient. Therefore . until these ques- tions are more ctearly answered. AAAS-T remains a provisional entity In support of a myeloproliferative compo- nent to this neoplasm, the majority of cases reooeted as RAAS-T have shown the JAK2 V617F mutation, or much less commonly. the MPL W515KIL mutation 1234. 354, 762, 1835. 1839. 1969. 2081, 2139. 23581_ On the other hand. the few reported cases with this mutation that have been studied for endogenous colony formation in vitro have demonstrated a pattern more akin to that of MDS 1234. 18351. Thus it may be that the provisional design ation of an MDS/MPN accurately reflects the underlying biology in a sub- stantial proportion of the patients 1762J; more study is needed to further ctarify this disorder. Cases with isolated del(SQ),t(3;3)(q21;q26) or inv(3)q 21q26) are excluded from this category, as are cases with a BCR·ABL1 fusion gene, In addition, if there has been a prior d iagnosis of an MPN without ring sioercotasts. or there is evidence that the ring stoerotsasts might be a consequence of therapy or represent disease prog res- sion in a patient with features that meet the criteria of another well-defined MPN, this designation should not be used. Genetics The recent discovery that up 10 60% of patients with AARS-T harb our the JAK2 V617F mutation (an incidence similar to that found in ET and PMF) or less corn- mon ly, the MPL W515KjL mutation, not only elucidates the reason for the prolifer- ative aspect of AARS-T but also woold seem to move it closer to the MPNcatego) 1234, 354. 762. 1835, 1839, 1969,2081, 2139, 23581. Thus. studies for JAK2V617F, and. if indicated, for the MPL W515M mutation should always be performed in such cases . of targe atypical megakaryocytes similar to those observed in BCR-ABL1negative MPN (See Chapt er 2). The minimum platelet count required for inclusi on has been lowered to 450xlCY'/L from 600x109/L for consistency with the defining criterion for ET, and because several studies have demonstrated that patients with platelet coun ts lower than 6OOxlCY'/L may have biological features, including JAK2V617F mutations, similar to those with coun ts ~x1Cf1A..1354I . It is important to note that the criteria for AAAS-T includes morphologically abnor- mal meqakarvocytes similar to those observed in ET and in PMF. This criterion should aid in distinguishing AAAS-T from those cases of RAAS commonly reported to have a modest increase in their platelet count. Nevertheless, we recommend test- ing for JAK2 V617F when the platelet count is elevated in patients with AARS until the borderline between AAAS and AAAS-T is more clearly defined ..Fig.' .13 Refractory eneema WIth ring SideI'Ob~s andlhfombocylosis This sequence ofrnitrophotogriljtls AtsIr3lt blood and bone marrow 01 a 62-year-old manwho presenledwithsevere anaemia anda plateletcountoI85lb:10"l AAbnormalred cellsandIhrontlocylosis. BEl)'lhroid proliferation and abnormal megakaryocylll$ reserrtIing megNy- ccytesseen inET. CMild dyserythropote$is. 0 The majority01 erythroid pIlICllfSOrS were ring sicleroblasts. 9982/3IC().() code 86 MyelodyspiastiC/myeloprollferallVe neoplasms
  • CHAPTER 5 Myelodysplastic Syndromes Myelodysplastic syndromes/neoplasms. overview Refractory cytopenia with unilineage dysptasia Refractory anaemia with ring siderobtasts Refractory cytopenia with multilineage dysplasia Refractory anaemia with excess blasts Myeladysplastic syndrome with lsoleted del(Sq) Myelodysplastic syndrome, unclassifiable Childhood myelodysplastic syndrome
  • Myelodysplastic syndromes/neoplasms, overview A.D. Brunning A.Orazi U. Germing M.M. Le Beau APOfWit I. Baumam J .W. Vardiman E. Hellstrom-Lindberg •Fig.5.02 Bone marrow smearfrom a . 1.year-d:l 'Mlh pancytoperia being cIYooic:aIy poiscWled lneIic. There isma'ked ~ M"",hoIogy The morphological classitication 01 MOO is principally based 00 the percent a blasts in the 8M and PB. the type an:! Etiology Primary or de novo MOS occurs without a known history of chemotherapy or race nonexpos ure. Possible etiologies for pre mary MOS Include benzene exposure at levels well above the minima allowed by most government agencies. cigarette smoking, exposure to agricultural cherri- cats or solvents and family history ci heematoootenc neoplasms 121131. Some inherited haematolog ical disorders. SUCll as Fanconi anaemia. dyskeratosis Cl)fo geni ta. Shwachmann-Diamond evnocre and Diamond-Brackten syndrome are also associated with an increased riska MOS. I- Clinical features The majority of patients present with symptoms related to cvtooentats): most of the patients are anaemic and transfusion- dependent. less frequent are neutropenia and/or thrombocytopenia. Organomegaly is infrequently observed. Fig. 5.03 Bone marrow smear from a57-yeaf-okl woman ¥r1'Io received several dl&molh&rapetJtlC ageotslorbreast carcinoma ir.clooing loIicacidantagonists. :. .It Fig. 5.01 Bone mamJIIIII smear from a palel1t 'Mlh ~s B19 irltedlon showing mal1<.ed eryttvoid hypoplasia wiltI occasional pi eryttYoblasts 'Mlh dispetsed dwomalin and line cyIqllasmic YlICUllIM. Epidemiology Myetodysplastic syndromes occur princi- pally in olde r adu lts with a median age of 70 years. with a non-age corrected annual incidence of 3-5/100 000 persons but rising to >20/ 100 000 among those ove r the age of 70 years {109, 7831. Approxi- mately 10 300 inciden t cases of MOS were diagnosed in 2003 in the USA {1351 1. There is a male predominance. Thera py-related mveioovsptasuc syn- dromes are discussed in Chapter 6. Definition The mve'oovsptasnc syndromes CMOS) are a group of clonal haematopoienc stem cell diseases characterized by cvtopeorats). dysplasia in one or more of the major myeloid cell lines. ineffective baematopoesis. and increased risk of development 01 acute myeloid leukaemia (AML) 1190. 353, 23101. There is an en- hanced degree of eoootosrs which con- tributes to the cytopenias 12601. The thresholds for cytopenias as recom- mended in the International Prognostic SCoring System (IPSS) lor risk stratification in the MDS are haemoglobin < lOgJdL. absolute reurroptut count (ANC) <18xl(Jl/l and platelets <l00xl(JlL 1833. 833AI. Values above these thresholds are. however, not exclusionary for a diag- nosis of MDS If delinitive morphologic and/or cytogenetic findings are present 123271. The dysplasia may be accompa- nied by an increase in myeloblasts in the peripheral blood (PB) and bone marrow (BM) but the number is <20%, which is the requisite threshold recommended for the diag nosis of AML. It is important 10 recognize that the threshold of 20% blasts in the PB or 8M for the distinction of AML from MDS does not represent a therapeu- tic mandate for treating pat ients with 20% blasts as acu te leukaemia . A treatment dec ision 10 manage the patient as AML or MDS must be based on seve ral factors including age, prior history of a mveoovs- plastic syndrcrne, overall clinical assessment and tempo of the process, which are the same determinant factors for patients with 30% blasts. Although progression to AML is the natural course in many cases of MoS, the percentage of pa tients who progress varies substantially in the various subtypes; a higher percentage of MDS wittl increased myeloblasts transforms to AML 178 1.13711 Althoughthemajorityof MOS are characterized by progressive 8M Iail- ure. the biOlogiCcourse in some patients. e.q. refractory anaemia with unilineage dysplasia (RA) and refractory anaemia with ring sroerobtests (AA AS). is pro- longed and indolent with a very low inci- denced evokJIi:rI toM1L 1781. 1370. 23271. 88 Myelodysplastic syndromes
  • degree of dysplasia and the presence of ring sideroblasts {1 90I. The cy topen ias generally correspond to the dysplastic lineage. but discordance may be present (Table 5.0 1) 123271. To determi ne the blast percentage in the BM, a 500-ceU differential of all nucleated cells in a smear ortrephineimprint is recommended and in the PB, a 2QO.leukocyte cnnerentrat In severely cvtooenrc patients, butfy coat smears of PBmay tacuuare performing the Odferential. The characteristics of the dysplasia are relevant when diSlinguishing between the various types 01 MOS and may be impor- tant in predictmg biology. In addition , some cytogenetic abnormalities are associated with characteristic dysplastic features, e.g isolated del(Sq) and hypo- lobated and non-lobated megakaryocyte nuc lei and det(17p) with hypolobeted neutrophil nuclei /12371 Assessment 01 the deg ree of dysplasia may be problematic depending on the quality of the smear preparations and the stain. Poor quali ty smears may result in misinterpretation of the presence or ab- sence 01 dysplasia particularlyin assessing neutrophil granula tion. Because of the critical importance 01 recognition of dys- plasia to the diagnosis of an MOS, the necessity 01 high quality slide preparations cannot be overemphasized. Slides for the assessment of dysplasia should be made from freshly obtained specimens; speci- mens exposed to anticoagulants for more than two hours are unsatisfactory As a general precaution, no patient should be diagnosed as having MOS without knowledge 01 the clin ical and drug history and no case of MOS should be reclassified while the patient is on growth teeter therapy, including erythro- poietin. In add ition, cytopenia(s) in the absence of dysplasia should not be interpreted as an MOS. A presumptive diagnosis of MOS may be made in the ab- sence of dysplasia il certain cytogenetic abnormalities are present (See Genetics). Persistent cytopenia without dysplasia and without one of the specific cytogenetic abnormalities considered as presumptive evidence of MOS should be viewed as the recently described "idiopathic cytopenia of undetermined siqrufcance" (leUS), and the patent's haematologic and cyto- genetic status should be cerefuny moni- tared 124221. In an attempt to more accurately predict chnical behaviour, cases of MOS without 8q'qlenIa may 0CCiI5i0naIy be obseMld casesWl1l'I pancytopenia should be classified as t.I05--U. I . .. JIlafl'DW myeloblast perc:entBge is <5% bul1tlEWe ere 2--4% myeIoblasls nee blood,ee liagnosticdass1Iic:aticrl is RAEB 1. Cases01 RCUO and RCMDIIo'ilh I%- Il)'IlIoblasts IIIlhll blood shoUlIbe dassifled as MOS, U Cases W1111wfII rods nI <5% myetlbIasls III 'lie bloodarw3 0(10% ineeI'!llll1tIW sInJIdbe d8s$lIied... RAEB 2. "'- ReIrDIlyq10perIIas 'IIII1lriineage dysplasia (RCOO) Refraclory anaemia (RA); Relracloryneutropenia(RN); _ _ IRT) Retacklry anaemiI WIth nngsidetobltsts (RARS) Refradory anaemia Withe~C8SS b1asts--1 (RAEB-1) Refractory ana&mia withexcess blasts-2 (RAEB·2) M)'elodj'Splastic syndrome - undaSSifJed (MDS-U) 8100dMdinp ~ orbicytopenia' t«I or rareblasts « 1%)1 -No "'''' Cylopenia(s) Noorfareblasts « 1'10)2 NoAlIeI'rods <'~10"11. monocytes Cytopenia{s) <5%blasts' NoAutlr rods < 1 ~1O"fl mooocytes Cytopenia(s) 5-19% blasts Auerrods t 1 <1~10'J1. mooocytes Cytopeflias 5:1% blasts ' """""UsuaRy J'M)n1I3I or we.ased pIaIeIet COUI1l Noor rareblasts «,%) IJn*IeagedysplaSIa.2:10% dille cells Ifl onemyebd i1eage <5%_ <15'10 01 eryIhrOId precursors are nngSlderobIasts 2:15%01 eryIhroid precursors onrilg SlderobIasts Erylhmid dysplasia only <5%blasts Dysplasia i'I 2:10%0I1I'le cellsin 2: two myeloid Iil'le<tges (neutrophil and/orerythroid prealrsOfS and/or megallaryocyles) <5'10 blasts in marrow NoAuIM rods 1;15'10 ringsideroblasls Unilineage orml,lttl l~age dysplasia 5-9% blastsl NoAuerrods Unilineage ormullilineage dysplasia 10-1 9"1o blasls Auer rods 1;1 Uoequivocal d~sia inlessIl<In 10% 01 eels ill one or moremyeloid celljoesv.t1en a<:compaflied by a C)'ogene~c abnormallt)' considered as presun1pIlve evideflCe fora diagnosjs 01 MDS (see Table 5.(4) <5%blasts Normal10increased megakaryocytes WJ1h tJwoIobated fIUdei <5%blasts Isolated del{5q) cytogenetic al:inl:lrmlliTyNo_ _
  • Ch.aracteristics of dysplasia Dyserythropoiesis is manilest prine by alterations in the nucleus ine budding, internuclear bridging, karyCI- rhexis, mu/tinucl€arity and megalobla changes; cytoplasmic features . ring siderobIasls. vacooIisalionand penxk acrd-Sctnf positivity. either diffuse (I granular (Table 5.03). Dysgranu!opoiesl is characterized primarily by nudelJ hypolobation (pseudo Pelqer-Hoetj a~ hypersegmentation. cytoplasmic hypo- granularity. pseudo Chediak-HigaS'J granules and small size. MegakaryocytP dysplasia is characterized by micro- megakaryocytes with hypolobated nuclEi, non-lobated nuclei in megakaryocytesIi all sizes, and multiple, wrderv-seoaraiea nuclei, Megakaryocytic dysplasia maytlt more readily app reciated in 8M secncs than smears and both types 01 specimers should be evaluated The characteristics of the dysplasia maj be relevant in pred icting biology of a mveicoysorastc disorder and the relatco- ship to specific cytogenetic abnormalities, ego Sq-syndrome {2327}, Unilineagedys- ptaaia is observed in RCUD and RARS Multilineage dysplasia involving two c. three of the myeloid ce ll lines is rTlOfe frequently observed in the high-graClt MDS and is used to distinguish ReM!) from ACUD 118641. Similarly, the presence 01 multilineage dysplasia is used separate RARS from RCMD with n sroerobtasts. the latter of which hasa similar clinical course to RCMD_ increased number of ring sioerotnasa occasionally> 15% of the erythroid pre- cursors. may be observed in refract anaemia with excess blasts (RAEB). TIt defining criteria of RAEB- l or RAEB-2 dictate the classification in such cases ~ 1 0% dysplastic megakaryocytes basec on evaluation of at least 30 megakaryo. cvtesin smears orsections, Future snoes may result in modification or this recco- mendation 114201. Mcromeqakaryocves and mullinucleate megakaryocytes are the most reliable dysplastic findings inttl megakaryocyte series 11420. 23271. Although the majority of patients w MDS and unlineage dysplasia pre with a single cytopenia. this revised etcatoo allows lor bicytopenia in refracb'y cytopenia withlXlilineage dysplasia (00,.q and RARS (Table 5.02). The majority~ patients with RCMD have 2 cytopeMS 118641. -.• - Categories Refractory cytopel1ia with unilineage dysplasia (RCUD) Refractory anaemia (RA) Relfactory I'le(Jtropenia (RN) Relfactory tnrombocylcpenia (RT) Relr<lclory aI1aerTlla withring SIIiIroblasts (RAAS) MyelodysplaslJc syndrome.uocIasS/fled (MD5-U) Retractory cyIOpenia Wllh mullilneage d:y$plaSiII (RCMO) erythroi d cells. In refractory cytopenia with mullilineage dysplasia (RCMD) with or without ring sioe robleete. significant dysplastic features are recognized in two or more of the major myeloid cell lineages. The recommended requisite percentage of cells manifesting dysplasia to qualify as sig nificant is ~ 10% 11864J in the erythroi d precursors and granulocytes, Significant megakaryocyte dysplasia is defined as Oysplasla Unilineage UflIinelIge and 2:15"" ringSideroblasts ""","", --(2:2myeloid eels Ines) - Cytopenia(s) Unicytopenia Bicytopenia -...Biq10penia p- "--" ' - ---" ' - --""Fig. 5.05 A Blood smear from apaJ8I"It on grarUocyte COOny sbmulating!acttJr. Aneutrophil W'IIh a bIlobed nucleus andnaeased azuror:I* grClruabon. B The same SI)Itinen as (A) showing amyeloblast. - Table 5.02 Summary ofcytopenias anddysplasia characteristics in MOS without an illCfease of marrow blasts. an increase in blasts are recognized as manifesting either unilineage or multilin- eage dysplasia In RA and RAAS. the dysplasia is generally confined 10the ery- throid lineage. Unilineage dysplasia may also occur in the neutrophns. refractory neutropenia (AN), and megakaryocytes. refractory thrombocytopenia (AT), but these processes are much less frequent than unilineage dysplasia involving the ,- 90 Myelodysplastic Syndromes
  • FIg. 5.11 BtnucIeate mega~ in a bone marrow smear from a pabeflt with• ~ history 01 refrackIry 1hrontlocytopen There isacentral !13f1JIOt'nereand a peripheral hyalomere. Fig.5.10 Neutn:lphi WIlll ar'lOI'Hlbaledru::Ieus (pseuclo PeIger-HuiIJ in. bbXI smear from a paIienl on~ mol3ZOle. ApproXllTlalely 50 percent01 the neuIrtlpt* hada simiarappearance. Histopathology The value of the BM biopsy in MOSis well established 116471. It may aid in confirming a suspected diagnosis by excluding reactive conditions in which ovsnaemato- poietic changes may also be observed: it can also increase the diagnostic accu- racy and helps in refining the IPSS score 123281. Assessment of 8M cellularity and strcmal reactions, e.g. fibrosis. B!eadditi:Jrl<W striking nuclear hypolobation 11968): blasts may be observed in the PB and may reach levels of 9- to% and rarely higher in patients with no evidence of AML or MOS. The 8M blast percentage is gener- ally normal, but may be increased as well. Paroxysmal noct urnal haemoglobinuria may also present with features similar 10 MOS. As a result 01all these possibilities. it is extremely important to be aware of the clinical history including exposure 10 drugs or c hemicals and cons ider non- clo nal disorde rs as possible etiologies when evaluating cases with myelodyspla- sia, particularly those cases with no in- crease in blasts. Repeated 8 M biopsies. including cytogenetic studies, over a pe- riod of several months may be necessary in difficu lt cases. • A. ... Fig.5.09 Dysplasbc megakaryocyeS. Bone n'llWl'OW as- pirate smear from a 37-year«l maleWIIh ~ stIotMgmegaka-yocyleswithdysplaslic features. • of AAEB-2 or CMML-2 in the con text of MOS or MOS/MPN rega rdless of the blast percentag e. This concept is reta ined in the present classification. Cases of MOS with <5% blasts in the 8M and <1% in the P8 may rarely have Auer rods. These cases have been reported to be associ- ated with an adverse prognosis 124151. Differential diagnostk: considerations A major problem in the diagnosis 01 MOS is the determination whether the presence 01 myelodysplasia is due to a clonal disor- der or is the result of some other factor. The presence 01 dysplasia is not in itsell definitive evidence of a clonal disorder. There are seve ral nutnnoner. toxic and other factors which may cause myelodys- plastic changes, including but not limited to vitamin 8 12 and folic acid deficiency, essential element deficiencies and expo- sure to heavy metals, parncutarts arsenic and several commonly used drugs and biologic agents 12601. The antibiotic cotreroxezoie may cause marked neu- trophil nuclear hypolobation indistinguish- able from the changes observed in MOS. In some patients on multiple drugs it may be difficult to identify the causative agent of the neutrophil changes 11136. 21411. Congenital reematoioqcat disorders such as congenital dyserythropoietic anaemia must also be considered as a cause of dysp lasia when it is confined to the ery- throid cells. Parvovi rus B19 infection may be associated with ervtn robreetopente wilh giant megaloblasloid erylhroblasls: the immunosu ppression age nt myco- phe nolate mofetil may also be associated with erythroblastopenia. Chemotherapeutic age nts may result in marked dysplasia of all myeloid ce ll lineages. Granuloc yte colony-stimulating factor result in mor- pholog ic alterations in the neotrophns. incl udin g marked hypergranularity and ••:- .~ --f.. 5.01 M~a stJc dysery1hropoIeSil. Bone MlIo ~ Inm., ao:Ul JT8B -Mlh fefracUy ~ .. rrUl*leage dysplasia (RCMD) and complex ~ 8t:n:lnnIIlItle N:tdng del(17p) anddel(Sq). The relationship between cvtopenras. type of dysplasia. and classification is summarized in Table 5.02 . The significance of the Auer rod in myeloid disorders has historically been sonewttat uncertain. For several decades Its detection was viewe d as virtually diag- nestle of AML. There was no specificity applied to it with the introduction 01 the concept of MDS by the FA8 group. In the revised FAB classification of 1982 it was veweoas evidence of a high-grade MOS. refractory anaemia with excess of blasts intransformation, (RAEB t ), irrespective of the blast percentage in the PB or 8 M 11901. In the prior WHO Classification of theMDS it was considered as evidence Fig. AAtmrmaIbcaizaIon01 inmaIu'e~. Bone marrow sectJon lI'om I ease 01 RAE&-l allIlain$ I locus 01 immature myeloid preo.nor$. SAlocus 0I1nmnJrec:eIIs in. bone rnatTOW biopsy from aesse 01 RAE&-2 reacted wl1t1 I nbbody kI C034. A lI'Iap:II'Ity oIlhe mmature eels are posilMl. , Overvrew- 91
  • Fig. $.12 A Bone marrow bI:lpsy from a case ofMDS(RAfB) WIth /I'I)'eIOfb'osi5everaI ~ iIIe presenl B Retio.anstainona marrow bclpsy from a case ofMDSwilh myelofibrosis. There isa marked inaease II retia.Wl MIres. important diagnostic features of the biopsy. The 8M in MDS is usually hyper- cellular ex oormocenutar: the cvtopenras result from the ineffective reenatcooese. Histologically, aggressive MDS may be characterized by the presence of aggre- gates (3-5 cells) ex clusters (>5 cells) of blasts in 8M biopsies usually localized in the central portion of the 8 M away from the vascular structures and endosteal surfaces 01 the bone trabeculae. These are frequently present in RAEB. The blasts can also be identified by immunohisto- chemistry with anlibody to CD34, an anti- gen expressed in progenitor cells and Table 5.lJ3 Morphologic marule$tabons01 ~ Oyserylhropolesll Noclear budding Int&rTll.lClear bridging Karyorrtlexis Mll~inuclearity Nuclear hyperlobation Megaloblastic changes Cytoplasmic Ring sideroblasts ~izaliOn PeriodiC acid-SChiff positvily ~granulopoie. l. SmaI or oousually largesize Nuclear hypoiobaliOn (pseudo Peiger-Huet: peIgeroid) IrT9{PJIar hypetSl:lgmentation Decreased granules: agrarWrity PseucIo QledIak-HtgastH ~arws ....""" ~l)'ocytopoiIs ls --NudNt hypoklbllJon ~ (normaI .,..katytq1es in I.lI'W'IJl:illI wilhkltdaled nudeI) 92 Myekxtysplaslic syndromes early precursor 8M cells in lhe majorIty of cases. Antj-C034 can be used to demon- strate pathologic accumulations of blasts both singly and in clusters in aggressive subtypes of myeloid neoplasms 120501. With some fixatives, CD34 will also im- munoreact with megakaryocytes in MOS, IrTYTlunohistologicanalysis with anti-C034 may be especially useful in cases 01 MDS with fibrosis or hvpoceuuiar marrows as well as therapy-related cases to assess blast percentage. In these instances the presence 01fibrosis ()( fany changes in the 8M may make accurate cbaractenzanon of the process very difficult. Hypoplastic MDS In a minority of the cases of MDS, approx- imately 10%, the 8M is hypocellular. These cases have been referred to as hypoplastic MOS. This group , which has no inde- pendent prognostic significance per S8, may lead to difficulties in the dif/eren lial d iag nos is with aplastic anaelT)i~ 1834. 16481. In addition, anti-thymocyte globulin and other therapies used for aplastic anaemia have been used with some deg ree of success in this subgroup 1260, 1302, 2477, 24781. It is also impo rtant when con- sidering the diagnosis of hypoplastic MDS 10 exclude toxic myelopathy and au to- immune disorders. MDS with myelofibrosis Signilicant degrees of myelofibrosis are observed in approximately 10% of the cases of MOS. These cases have been referred to as MDS with fibrosis (12461. Most of the cases with fibrosis have ex- cess of blasts and an aggressive clinical course. Such cases may erroneously be considered low-grade MOS if only the blast count determined from the 8M aspi- rate, which is usually diluted With P8 , is evaluated. In the fibrotic group, as in other cases of MDS with inadequate aspirates, the blast determination requires a aM biopsy and immunohistochemical studies for C034 may prove invaluable. 1l1VTlUnophenotyping Published studies on immunophenotyprg by flow cytometry in MOS have focused CI'l several strategies, including determrwg the size and immunophenotype of ee blast population and assessing the matu- ration pattern 0I1he myeloid cell popUatol More specifically. these studies included immunophenotyp ing of CD34+ cells, ap. plication of SCOfing systems, and pattern recognition strategies uSing muttiCOO analysis and comparison with norrn;iI reactive PB and 8M. There is generally good correlation be- tween the percentage of blasts as cere- mined by morphologic examination iJ fOJtine smearorirr'pV'ltor~ preparations and percentage of CD34. cells determined by flow cytometry (FC~ However. in some cases there may be significant discordance due to signilicart myelofibrosis and haemodilute samples As a result, Fe percentages 01 CD34+ eels cannot replace differential counts 00 smears, However, Fe may be informal1Ye~ abnormal phenotypes of C034+ cells are detected: this could be additional evidence f: dysplasia. In addition, an emerging athological population of CD34 IJ 01 17 cells in low-grade MDS could Sl.I9" gest evolution of the disease 116221. Maturation patterns of erythropoietic granulocytic, and monocytic difterentiatcn in the normal/reac tive 8 M, as well as the immunophenotype of the mature cellsin PB have been thoroughly described using four-color FC. Erythroid abnormalities as determined by the pattern of exoressce of H-ferritin, CD71 and C010S in gly· cophorin A (GPA) posi tive nucleated cells reportedly can pred ict morphological ery- throid dysplasia with 98%sensitivity [5501, Aberran t maturation patterns in granu- lopoiesis could predict morphological dysplasia and abnormal cytogenetics in approximately 90% of cases 112121. ThJs flow cytorretrv results correiate well with morphology and cytogenetics in MDS However, in cases with borderline dys. plasia by morphology and no cytogenetic abnormalities. FC results are highly sug- gestive for MOS only if there are three IJ more aberrant features in erymropoietc. granulocytic or monocytic maturation; single aberrant features by FC are na
  • Table 5.05 International PrognosticSC:or1'1g System(IPSSllorMDS (833,833Af. SeePrognosis and pt'edidive faclQrs lorinterpretation, "This ~ is~ asAML in thewtK) classificabon. - Karyotype: Good" normal, -Y,del(5Q). del(2Oq). Poor " ~l ~ lIbnormaIiIies) or....~~mlTlOSOl""'m..18 7...::ma1ies: Intermecliate " otherIIbnormaIrt.oes - Cylopenias: Hgb<1llgk1. NeutropIiIs <1.8xlll'11. PIaWets <1 00x1 ~ ,,~ • ••• , ,.s 2 Prognostic variables " bone marrow blasts <5. 5-10% 11- 19"110 20-30%' Karyotype" Good Intermediate Poot C~s- .-, 2-3 significant. .Cases with inconclu sive morphologic and cytogene tic find ings and three or mo re aberrant fea tures by flow cytometry should be reevaluated over several mon ths for definitive rrorpro- logic orcytogenetic evidence of MOS, Genetics Cytogenetic and molecular studies have amajor role in the evaluation of patients withMOS in regard to prognosis, deter- mnatonof clonality {833, 16411, and the 'ecognltion of cytogenetic , morphologic, m clinical correlates . Clonal cytogenetic abnormalities are observed in - 50% of I,()S cases. Myekxtysptastic syndromes associated with an isolated del(5q) occur orinarity in women, are characterized by megakaryocy1es withroo-ocetec Of hypo- klbated nuclei, refractory macrocytic anaemia, normal or increased platelet Cl:lOOt, and a favourable clinical course, and are recccneec as a scecinc type of MDS in this classification, Theoccurrence (j 17p loss is assoc iated with MOS or AML with pseudo Pelger-Hu6t anomaly. small vacuolated neutroohlrs. TP53 muta- tion and unfavourable clinical course: it is rest common in therapy-related MOS (12371· Complex karyotypes (2:3 abnor- malities) typically include chromosomes 5 andfOf 7 [-S/del(5q), -7/del(7q )), and are generally assoc iated with an unfavourable clinical course. Several olher cytogenetic lindings appear to be assoc iated with characteristic morphologic abnormalities such as isolated del(20q) with involve- ment of erythroid ce lls and megakaryo- cvies. and abnormalities of chromosome 3(irw (3)(q2 1q26,2) or t(3 ~3)(q21 :q26,2)]. which are associated with MOS and AML withincreased abno rmal megakaryocytes 1289, 866, 1207j. Some clonal cytogenetic abnormalities occuring in MOS are not definitive evi- dence for this disorde r in the absence of morphological crtterte. e.q. -Y, +8 or ool(2Oq) as the sale abnormality, The other abnormalities listed in Table 504 in ee presence of a refractory cytopenia, but no morphologic evidence of dysplasia, are considered presumptive evidence for MOS. It is recommended thai tnese pa- llefllS be followed caretcuv lor emerging roorphological evidence of MOS. FISH tJOVides increased senSitivity in monitoring Sl.Ch pateots.oncea recurring abnormality res been identified , Postulated cell of origin Haematoooetic stem cell. Prognosis and predictive factors The morphological subtypes of MDS can be generally categorized into three risk groups based on duration of survival and incidence of evolution to AML. The Iow-risk groups are RCUD and RARS. The inter- mediate-risk groups are RCMD with or without ring srderobrasts and RAEB-1, Pa- tients with RAE&-2 constitute the high-risk group. It should be noted that patient s with bcvtopema in RCUO and RARS have been reported to have a shorter surviva l than patients with one cytopenia 123271. Patients with one cyt openia in the context of RCMD had a longer survival than pa- tients with two cvtocenras 123271· The importance of cytogenetic studies as a prognostic indicator in MDS has been recogniZed and cod ified by the Interna- tional Myekxtysplaslic Synd rome Working Group 18331· Three major risk categories of cytogenetic findi ngs have been de- fined : i) good risk -normal karyotype, isolated del(5q), isolated del (2Oq) and -Y; ii) poor risk ---complex abnorma lities, l.e., 2:3 abnormalities, or abnormalities of chromosome 7; and iii) intermediate risk - all other abnormalities. A scoring system for predicting survival and evolution to AML based on percent 8M blasts. type of cytogenetic abnormal- ities , and degree and number of cytcoe- ntas has been pro posed by this group (Table 5.05) 1833, 833AI, Four risk groups based on this scoring system are recog- nized : low, O' INT (interme diate)-1, 0,5-1.0; INT-2, 1,5- 2.0; and high , 2:2,5. In general, the higher-risk groups are related to higher 8M blast percent age, mo re un- favourab le cytogenetic findings and mo re Tabl. 5.04 ReCl.lningcluumosomal abnormalitiesand their frequency in re myelod~aslic syndromes at diagoosis. A_" MO' ,-110, """"""""' S' ' 0% ·1 ordel(7Q) ' 0% ""'-5 ordel(Sq) ' 0% ""'- ,' .....r S% ~ 17Q) orl(17p) . S% .13 ordel(13Q) '"del(11Q) '"del(12p)Of1(12p) '"-, ' .2% dc(X)(Q13) ' .2% -1(11;16)(q23,p13.3) '"1(32 1)(q262;q22.1) 2% 1(1;3)(p36.3:~1.2) ..1(2;1l)(p21:Q231 ..~3)(q21q26.2) ..1(6:9)(p23;q34) .. , The ceseece of these at:JnormaIIies as the sc*l ~ abrmnaiIy 11 !he absence ofrrupho- logic aTlenaisno! considered deMiIiveevidence lor 1.40S, In !he seltlng of persistent eytapenias ol ~ origin. lheoll'ler abnormahties shoWn areIXIO~ ~ve evidence 01 MDS inthe absenc:e 01 defu'itive ITlCfPlIOIC9Cfeatures. severe degree of cytopenia. Constderatoo of age improves predictabil- ityof survival; patients younger than 60 years of age have improved survival in the ind ividual risk ca tegories compared with patients older than 60 years. The cytoge netic subgrouping of the IPSS system also has an independ ent value in pred icting the outcome of allog eneic stem cell transplantation in patients with MOS 15321. i Overview 93
  • Refractory cytopenia with unilineage dysplasia A.D. Brunning A.P. Hasserjian A. Porwit J.M. Bennett A. Orazr J. Thiele E. Heustrorn-Ltndberq Fig. 5.13 Refradory WIlIeIT'Iia, Thisbone IIWTt7W smear speomen shows dyspIasbc Jeatures criy in !he8f)1tVOld preo.nors; octaSiOnaI erythrobIasl$ sI'lClW vacu:lIat8d c:ytopIasm Mel~ megakXVst*! 1'oldBi. Definition Refractory cytopenia with unilineage dys- plasia (RCUD) is intended to encompass those myelodysplastic syndromes (MDS) which present with a refractory cytopenia with unilineage dysplasia and includes refractory anaemia (RA), refractory neutro- penia (RN) and refractory thrombocyto- penia (AT). Although refractory anaemia with ring sioercoiasts is also characterized by unilineage dysplasia. it is considered as a distinct entity of its own. Refractory bicytopenia may be inCluded in the AGUD category il accompanied by unilineage dysplasia. It is recomnet ICIed that refractory pancytopenia with unilineagEl dysplasia be placed in the category 01 rnyelodysplastic synd rome. unctassrnaore (MDS·U). The recommended level lor dysplasia is ~ 1 0% in the cell lineage affected. The recom- men ded levels for defining cytopenias are haemoglobin <10g/dL. absolute neutro- phil count (ANG) < 1.8x1Ql1IL and platelet count <100x1(19/l1833, 833AJ. However, values above these levels do not exclude MDS if definitive morphologic and/or cyto- genetic evidence of MOS is present. The type of cytopenia in the majority of cases will cor respond to the type of unilineage dysplasia, e.q. anaemia and erythroid dysplasia, although discordance between type of cytopenia and cell lineage dyspla- sia may be observed 123271. Some of the cases previously classified as M05-U may be included in this category. e.q. RN, RT All non-clonal causes tor the dysplasia must be explored and excluded before the diagnosis of MOS is established These include, but are not limited to, drug and toxin exposure, growth factor therapy. viral infections, immunologic crsorcers. congenital disorders, vitamin deficiencies and possible essential element deficien- cies, such as copper deficiency 18371_ Excessive zinc supplementation has also been reported to be associated with se- vere cytopenia and dysplastic changes 110 101. It a clonal cytogenetic abnormality is not present, there should be a period of observation of six months from initial examination before a diagnosis of MOS is established unless more definitive morpro- logic or genetic evidence emerges during the observation period. The presence of peripheral blood (PB) blasts essentially excludes a diagnosis of RCUD although in an occasional case a rare blast may be identified: patients with the findings of RCUO and 1% blasts in the PB and <5% in the bone marrow (BM) on two successive evaluations should be placed in the category of MOS-U because ofthe uncertain biology ofthis constellation of findings. Patients with 2-4% blasts 11"1 the PB and <5% blasts in the 8M should be classified as refractory anaemia With excess btasts-t (RAEB-1) if other cntere lor MOS are present. The number d cases with these findings is very lowana these patients stoJd be careftAly coseoec for increasing 8M blast percentage 111651, Refractory cytopenia with unilineage dysplasia should not be equaled wiVl "Idiopathic cytopenia of undetermined signiftcance" (ICUS) which lacks the minimal morphologic or genetic criteria requisite tor a diagnosis 01 MOS and should not be considered as such [24221. Synonym Refractory anaemia. Epidemiology Refractory cytopenia with unilineage dysplasia comprises 10-20% of all cases of MOS 1782, 1371/. It is primarily a ds- ease of older adults; the median age is around 65-70 years There is no signifi· cant sex predilection, The vast majorityo! RCUD cases are RA. Refractor y neutro- pen ia and refractory thrombocytopenia are rare and extreme caution should be used in making either of these diagnoses. Sites of involvement The P8 and 8 M are the principal sites 01 involvement, Clinical feature s In RCUO. the presenting symptoms are related to the type of cytopenia, The cyto- per nas are refractory to haernauruc ther- apy, but may be responsive 10 growth factors 19831. Mo<phology Refractory anaemia oco-ocode 998013) In the PB in RA, the red blood cells are usually normochrcmic, normocytic or nor- moctYomic, macrocytic. Unusually, there is anisochromasia or dimorphism with a 94 Myelodysplastic syndromes
  • _ A S Fif!. 5.14 A Refraclory neuuopel'lIa Bklod smearm a56-year-old male;!tiel'lIllAJq)hIinlhebwer IeflIS normal aweamgwith weI-grarIJIated cytJpIa$ITI andanamaIy M!1I'*'*I 1IJdIus.The A8IA"ophI inltlel4lP8l' rv-isdysplastic wiIh ~ ~ cyq:.Ia$mWld oc:casionaI 0CHe bode&. The I1.JdM; showsretarded MglIl8lI!alJOll. ApprounaleIy IlIIf01 fie nMropI'Iis 'III'8l1l dyspIaslic. Cytogenetic S!I..des showed .. extra toP'I d cnomosome 8 lWld perlOlft'lc rNer1ion d ctvornosare 12. B AtIyspIastic megakaI)uyte ina ~ ItTl8al' from a ll-year-okl male WIlIl a two year hISlory oIrelradory II1rtlmbocyk:Jp Theieis ~ Ikdearcylopiastllc dewelopll.,1 '/IIllh a ~ ~ and 8 norHobatedmnaltn nucleus. CytIgeoelic slldIes ' I this!line stoNed a missing Ychromosome. There wasSlbsequenC evokIIIon at which lime~ -.oesshcMoed arrWsSlI'lg Y, addltIonaI9 and deletion 13. e -- s a population of hypochromic red blood cells. Anisoc ytosis and po ikilocytosis va ry from none 10 marked. Blasts are rarely seen and, if present, account for <1% of the while blood cells. The nectrocnns and platelets are usually normal in number and rrorpno- logy. However, some degree 01 either neutropenia or thrombocytopenia may be present The erythroid precursors in the 8M in RA vary from decreased to rnatkedty increased; <tyseryltYopoie variestrern slight tomod- e ere. unequivocal evidence of dysplasia met be present in 10% or more erythroid precursors. Dyserythropoiesis is manifest principally by alterations in the nucleus includ ing budding, internuclear bridging , karyorrhexis. multinuclearity and mecato- blastoid changes: cytoplasmic features in. coosvacuolizationand periodic acid-Schiff positivity, either diftuse or granular. Aing sideroblasts may be present but are <15% iJ erythroid precursors. Myeloblasts ac- ooun1 for <5% of the nucleated BM cells, The neutrophils and megakaryocytes are 'l:lm'IaI or may show rnnimaJ dysplasia, but ~ways <10% in either cell line, The BM biopsy is generally hypercellular due 10 rcreased erythroid precursors. but may be rorrccenoiaroreven hypocellular. Refractory neutropenia (lCD-O code 9991/3) Refractory neutropeni a is ch aracterized by~ 1 0% dysplastic neutrophils in the PB or 3M;thedysplasia is principally manifesl as ru:::1ear hypoIobation and hypogranulation. Neutropenia secondary to drug therapy, toxic exposure, infectious processes , im- mune mechanisms, or other causative fac- tors must be excluded, The other myeloid cell lines do not show significant dysplasia «10%). Refractory thrombocytopenia (ICD-O code 9992iJ) Refractory thrombocytopenia is charac- terized by 2':10% dysplastic megakaryo- cv tee of at least 30 megakaryocytes evaluated: hypolcbate megakaryocytes, binucleate and multinucleate megakarye- cytes and mrcromeqakarvocvtes are the most reliable and reproduci ble features of megakaryocyte dysp lasia, Dyspl astic megakaryocyles may be more evident in sections than smears and usually well exceed the 10% threshold. The mega- karvocvtes may be increased or de- creased . The other myeloid cell lines do not show sign ificant dysplasia (<10%). Distinction frem chronic autoinvnune thrombocytopenia is cntc at and may be extremely difficult clinically and morpho- logically. Cytogenetic studies may be of consi derable aid in this distinclion 18661. Immunophenotype In refractory anaemia abe rrant immune- phenotypic features of erythropo ietic precursors can be found by flow cytometry analysis 15501. There are no data on RN and RT. Genetics Cytogenetic abnormalities may be ob- served in up to 50% of cases of refractory anaemia 1782J Several difterent acquired clonal chromosomal abnormalities may be observed. and although useful for establishing a diagnosis of RA, they are not specific. The abnormalities generally associated with RA include del(2OQ), .8 and abnormalities of 5 aod/Of 7. The num- ber 01 reported case s of AN and mis 100 low to allow for generalizations, although del(2Oq) has been reported in AT 1866. 19381. Postulated cell of origin Haematopoietic stem cell. Prognosis and predictive factors The clinical course is protracted; the median survival of patients wilh RA in one series was approximately 66 months and the rate of progression to AML at 5 years was approximately 2% 17821. In another study, the median survival tor pat ients over 70 years 01age with AA, RARS and MOS with del(Sq) was not sigml icantly different frem the non-affected population 11371 1. Approximately 90-95% 01patients with RA have low or intermediate Interna- tional Prognostic Scoring System (IPSS) scores 1833, 833AI. Approximately 80-85% have good to intermediate cytogenetic profiles 1782, 13711,Most patients with AT have tow IPSS scores and 90% of the pa- tients live more than twoyears 119381. . Refractory cytopenia with unilineage dysplasia 95
  • Refractory anaemia with ring sideroblasts R.P. Hasserjian N. Gattermann J.M. Bennett A.D. Brunning J . Thiele Epidemiology RARS accounts for 3-11% of MDS cases. It occurs primarily in older indivi duals with a median age of 60-73 years and has a similar freq uency in males and females 1267.782. 13711. Detinitioo Refractory anaemiawith nng stderoorasts (RARS) is a myelodysp lastic syndrome (MDS) cha racterized by anaemia. morpho- logic dysplasia in the erythroid lineage and ring eoercoteste comprising ~ 1 5% of the bone marrow (BM) erythroid precur- sors , There is no significant dysplasia in non-erythroid lineages. Myeiobiasis com- prise <5% allhe nucleated 8 M cells and are not present in the peripheral blood (Pe), Secondary causes of ring sroero- blasts must be excluded. EIOOgy Ring sideroblasls represent erythroid pre- cursorswithabnormal accumulation of iron within mitochondr ia. including some depo- sited as mitochondrial ferritin 1352, 827f. Primary def ects of haem synthesis (such as the a-amlnolevonruc acid synthetase defect in hered itary X-linked srderoblastc anaemia) can largely be excluded be- cause protoporphyrin IX, the end prod uct of po rphyr in synthesis, is not decreased in RARS 11 2091. Furthermore , acquired mutations in genes of the haem synthetic pathway have not been demonstrated in AAAS {20841 Therefore. a primary defect ICD-O code 998213 of mitochondrial iron metabolism is sus- pect ed . This defect may be caused by somatic mutations or deletions in nuclear or mitochondrial DNA. Potentially analo- gous congenital d isorders inc lude the Pearson marrow-pancreas syndrome , which features s.oerooiastc anaemia and is caused by congenital large oeetcos of mitochondrial DNA 1478/. Somatic point mutations 01 mitochondrial DNA have been identified in the BM 01 some patients with AAAS t7631 bu t it remains 10 be established whether they cause the soeo- blastic phenotype 114221. Clona lity 01 CD34-positive progenitor cells and erythroid and granulocytic elemen ts has been demon strated in RARS patients by x-cbrorosome inactivation analysis {549. 21261. Stem cells from AARS patients display poor erythroid colony formation in vitro and manifest abnormal iron depo- sition at a very early stage 01 erythroid development {444, 21781. This evidence suggests that RARS represents a clonal stem cell defect that manifests as abnor- mal iron metabolism in the erythroid lineage and results in ineffective erythropo iesis. Sites of involvement The PB and BM are the principal sites of involvement. The liver and spleen may show evidence of iron over load. Clinical features The presenting symptoms are related to anaemia. which is usually of mode rate de- gree; some patients may additionally be thrombocytopenic or neutropenic . There may be symptoms related to progressive iron overload. """"hology Patients typically present with norrTll'> ch romic macrocytic or normochromic normocytic anaemia. The red blood eels in the PB smear may manifest a dimor- phic pattern with a major population 01 normochromic red bkxxt cells and a minor population 01 hypochromic cells Blasts are not present in the PB. The 8M aspirate smear shows an increase in ery- throid precursors with erythroid lineage dysplasia. including nuclear lobation and megaloblastoid features . Granulocytes and megakaryocytes show no significant dysplasia «10% dysplastic forms). Haemosiderin-Iaden macrophages are often abundant. Myelob lasts are less mao 5% of the nucleated 8M cells. On an iron- stained aspirate smea r, 15% or more of the red cell precursors are ring srcero- blasts, as defined by 5 or more iron gran- ules enci rcli ng one third or more of the nucleus. The 8M biopsy is norrnocellularto markedly hyperceIlular. usuallywitha marked erythroid proliferation. Meqakaryocytes are normal in number and morphology. Ring sideroblasts are frequently observed in other types 01MDS 1776, 10781. For ex- amp le, cases with ring sideroblasts that have excess blas ts in the PB or 8M are classified as refractory anaemi a with excess of blasts (RAEB).When ring stoero blasts are 15% or more of the eryth roid precursors but there are 10% or more dys- plastic cells in any non-erythroid lineage. • A _ Fig. 5.15 RefratQy..aema WItl'l rtogsiderobIasts. A Blood smear wilhdmorphic red bklodeels and macrocyIeS (WrJItII-Giemsa). B8lnI 1lWfOlf aspt'aIe smear stlowIWlg I marked 8l)'ttlroid proIiferallon with ad)'5!JIBstlc Mderate bm (WrVrt-Giecnsa). CIronslain d boneIlWfOlfiISpQI8 sIll:JrMng I'U"I'letOUS ringsdetoblasts. 96 Myelodysplas!iC svnorores
  • ---1....- RCMD with 2:15% RS and blasts are < 1% in the PB and <5% in the8M with no Auer rods or monocytosis, the case is classified as refractory cyto- penia with mullilineage dysplasia (RCMD), Such patients have infe rior survival to patients with AARS. tbHleoplastic causes 01ring sideroblasts. including alcohol. toxins (lead and ben- zene). drugs (isoniazid), zinc aorrurustra- ton. copper deficiency and congenital sderootastc anaemia, must be excluded 1201. Irrrnunopheootyp In refractory anaemia with ring stdero- oests. aberrant immunophenotypic tea- luresof erythropoietic precursors can be lound by flow cytometry analysis 15501. 100 eo 0; .~ 60,0 "~ 40 •Q. 20 0 0 100 ~RARS 200 300 Months Genetics Clonal chromosomal abnormalities are seen in 5-20% of cases of AARS and, when present. typically involve a single chromosome 1267. 776. 7781. Postulated cell 01 origin Haematopoielic stem cell. Prognosis and pred ictive factors Approximately 1- 2% of cases of AAAS evolve to ac ute myeloid leukaemia. The reported overall median survival is 69- loa months 1549, 7781. FIg. 5.16 Stn;vaI Ctro'eS allerlong-lenn ~oI' 161patients WIth RARS and 318 RCMO patients WIltJ 2'15%mg siderotlIasts (RSI. showing i'ltenor survival lor lIIe pallents WIth mg sideroblasts and nUtiIineage dysplasia (p:O.ClCIOOS)(Datafrom ltIeDusseldorf UDSregislry), Aefractory anaemIa with ring soercoiests 97
  • Refractory cytopenia with multilineage dysplasia R D. Brunning J,M. Bennett E. Matures A. Orazi J.w. Vardiman J. Thiele Sites of involvement Blood and bone marrow Morphology The BM is usually hypercellular. Neu- trophil dy splasia is characterized by ....... Fig. 5.1' Refractooy ~ withrn.J~~ Bone marrow smearshowseviOenCe ee erythroidprecursors andthe neutropnils.The maItt neutrophils aresmall andMvallypolobulated rn.cIeI. hypogranulation and/or nuclear hyposeq. mentation with marked clump ing of the nuclear chromatin (pseudo Pelqer-l-iuet nuclei), The nuc lear hyposegm entation may occur as two clumped nuclear lobes con nected by a thin chromatin strand (ptoce-nez type) Of marked ly clumped non-lobated nuclei, Myeloblasts account for <5% of the 8 M ceus. In some cases there is a marked increase in erythroid precu rsors . Erythroid precursors may show cytoplasmic vacuoles and marked nuclear irregularity, including internuclear chromatin bridging, multilobation, nuclear budding, multmucleation and megalo- brastord nuclei. The vacuoles are usually poorly defined and dissimilar to the sharply demarcated vacuoles observed in toxic alterations such as alcoholism The vacuoles may be periodic acid-Schlll (PAS) positive; there may also be diffuse cytoplasmic PAS positivity. In RCMD, 998513ICD-Ocode blasts in the PB, <5% in the BM, and no Auer rods should be classified as refrac- tory anaemia with excess of blasts (RAEB)- l ; cases with 1% blasts orfewer in the PB and <5% blasts in the BM, and Auer rods should be classified as RAEB-2 ; cases with 1% blasts in the PB and <5% in the 8M and no Auer rods should be classified as MDS-U. Some cases of RCMD have 2:15% ring sideroblasts (782. 13711. Epidemiology Refractory cytopenia With multilineage dysplasia occurs in older individuals: the median age is approximately 70 years. There is a sligh t predominance of males. The peak incidence for males is 70-74 years, for females 75-79 years (7821. It accounts for -30% of cases of MDS 1782. 137 11. Clinical features Most patients present with evidence 01 BM failure with cytopenia 01two or more myeloid cell lines. Definition Refractory cytopenia with multilineage dysplasia (ACMD) is a type 01 myelodys- plastic syndrome (MOS) with one or more cytopenias and dysplastic changes in t'NO or rrore of the myeloid lineages: erythroid . 9mnulocytic. n-egaka<yocytjc 118641.rtere are < 1% blasts in the peripheral blood (PS) and <5% in the bOne marrow (8M); Auer rods ere not present and the mono- cytes in the P8 are less than lxHJ'I.. The recommended levels for defining cytope- nias are haemoglobin < lOgfdL absolute neutrophil cocnt <1.8xl()9/l and platelet count <100xl()11I.I633. 833A1. However, values in excess 01these thresholds are not exclusionary of a diagnosis of MDS if definitive morphologic and/or cytogenetic findings are consistent with a diagnosis. e.q. complex cytogenetic abnormalities . The thresholds lor dysplasia are ~10% in each of the affected cell lines. In assess- ing dysplasia it is recommended that 200 neutrophils and precursors and 200 ery- throid precursors be evaluated in smear and/or trephine imprint preparations. The neutrophil dysplasia may be evaluated in PB or BM smears. At least 30 megakary- cc ytes should be evaluated for dysplasia in BM smears or sections, In some ca ses, dysplastic meg akaryocytes may be more readily identified in sections than smears, In particul ar the presence of micro- megakaryocyte s should be noted. Cases with multilineage dyspl asia and 2-4% 98 Myek:!dYSplastlC syndromes
  • variable numbers of ring stoercorasts may be identified Megakaryocyte abnorma li- ties which may be observed include non- lobated nuclei, nvpotonered nuclei, binucleate or multinucleate megakary- ocvtes and micromegakaryocytes; the mi- cromegakaryocyte is defined as a megakaryocyte approximately the size of a promyelocyte or smaller with a non- lobated or bitobed nucleus and is the most reliable and reproducible dysplastic feature in the megakaryocyte series {1 4201_ Immunophenotype See Chapter on myelod ysplastic syn- oromesrneootasms. overview. Genetics Clonal cytogenetic abnormalities including trisomy 8, monosomy 7, del(7q). mono- somy 5, del(5q), and del(2Oq), as well as complex karyotypes, may be found in up to 50% of patients with RCMD {782, 8331. Postulated cell of origin Haematopoietic stem cell. Prognosis and predictive factors The clinical course varies. The majority of patients wilh RCMD has International Prognostic Scoring System (IPSS) scores in the intermediate category 1833, 833AI. Prognoslic factors relate to the degree ot cytopenia and dysplasia. The frequency of acute leukaemia evolution at two years is - 10% in RMCD 17821. The overall me- dian survival is approximately 30 rron ms. Patients with complex karvorvpes have survivals similar to patients with refractory anaemia with excess of blasts (AAEB) 17821. Refractory cvtooeoa WithmultJ!ineage dysplaSia 99
  • Refractory anaemia with excess blasts A.Orazi R D. Brunning R P. Hasserjian U. Germing J. Thiele Ep;demkllogy This disease affec ts primarily individuals over 50 years 01 age. It accounts lor ap- proximately 40% of all patients with MOS. Definition Refractory anaemia with excess blasts (RAEB) is a myelodysplastic syndrome (MDS) with 5-19% myeloblasts in the bone marrow (BM) or 2-19% blasts in the peripheral blood (PB) Because of differ- ences in survival and incidence of evolu- tion to acute myeloid leukaemia (AML). two categories of RAEB are recognized: AAEB-l, defined by 5-9% blasts in the BMor 2-4% blasts in the PB, and RAEB-2, defined by 10-19% blasts in the 8M or 5-19% blasts in the PB 18331. The pres- ence of Auer rods in blasts qualifies a case as RAEB-2 irrespective of the blast percentage 17811. ICD-O code 998313 FIg. 5.19 Relractoryanaemia Wl1tJ excess b1asts-1(RAEB-1J. Bone rnatrOWsmear.The malJ.l'e ~ I'Ihsc. show nuclear hypolobulabon (pseudo Pelger-Hll8Inuclei) and cytoplasmic hypograrnunty. Etiology The etiology is unknown. Exposure to en- vironmental toxins, including pesticides, petroleum derivatives and some heavy metals increases risk, as does cigarette smok ing 12113AI. Sites of Involvement Blood and bone marrow, Clinical features Most patients initially present with symp- toms rela ted to BM failure, including anaemia, thrombocytopenia and neutro- penia. "'"""",Iogy The PB smear frequently shows abnor- mali ties in all three myeloid cell lines. including red cell anisopoikilocytosis. large, giant or hypogranular platelets and abnormal cytoplasmic granUlarity and nuclear segmentation of the neutrophils. Blasts are commonly present. The BM is usually hyperceHular. The degree of dys- plasia may vary. Erythropoiesis may be increased withmacrocyticlmegaloblastoid changes. The erythroid precursors may 100 MyelOdysplastiC syndromes show dyserythropoiesis including the presence of abnormally lobulated nuclei and internucl ear bridging, Granulopoiesis is frequently increased and shows vari- able degrees of dysplasia. This is cha rac- terized primarily by small size neutrophils with nuclear hypolobation (pseudo Pelq er-Hoet nucl ei) or nucl ear hype rseg- mentation, cytoplasmic hypogranularity and/or pseudo Chediak-Higashi granules. Megakaryopoiesis is variable in quantity but is frequently norma! to increased. The megakaryocytes often show a tendency to c luster. Oysmegakaryopoiesis is almost invariably present and is usually cha rac- terized by the presence of abnormal forms predominantly of small size, includ- ing micromegakaryocytes 122261. How- ever, megakaryocytes of all sizes as well as forms with multiple widely-separated nuclei can also occur. The BM biopsy shows alteration of the normal tnstc- topography. Both erythropoiesis and megakaryopoiesis appear frequently dis- located towards the paratrabecular areas that are normally predominantly occupied by granulopoietic cells. In a minority of cases the BM appears normocellular orhvpocenuar. RAEBcases with hypocellular 8M represent only a small proportion of cases of hypoplasbC MOS, since most of these cases do rd show an increased number of blasts ana belong to the group of refractory cvtooere with unilineage dys plasia (RCUD) or less commonly to refractory cytopenia witn multilineage dysp lasia (RCMDl , The 8M biopsy can be very useful in documenting the presence of an excess of blasts per- ticula rly in cases with subo ptimal aspirate smears such as those associated wim a hypocellular and/or fibrotic BM. Blastsi1 AAEB often tend to form cell clusters II aggregates that are usually located a~ 'rom bone trabeculae and vascular snc teres.a histologic finding formerly referred to as abnormal localization of immature precursors (AlIP). Immunohistochemical staining for C034 may be particularty helpful in their identification. RAEB wilh fibrosis (RAEB-F): In about 15% of patients with MOS, ee BM stews a sign ificant degree of relCl.irl fibrosis. Such cases have been termed MDS WIth fibrosis (MDS-F) (1246. 1400/.
  • Since myelQfibrosis can be seen also in cases otmerapv -rerateo MOS, myelopro- liferative neoplasms, and, rarely, in reac- tive dyshaematopoietic conditions (e·9 HIV·related myelopathy) these conditions need to be excluded. Because of the lack of consensus on the degree of fibrosis necessary to characterize a case as MDS-F, it is stilt unclear whether fibrosis represents an independent prognostic parameter 120831. The current working definiloo of MOS-Frequires diffuse coarse reticulin fibrosis with orwithout coocomilant collagenizalion, associated with dysplasia in at least twocell lineages 12083, 23121. Most of the cases defined as MOS·F belong to the RAEB category (RAEB-F), The presence of an excess of blasts in these cases can usually be demonstrated using immunohistochemistry. particularly for CD34. The BM smears are usually inadequate. A characteristic finding in RAEB-F is an increased number 01mega- keryccv tes with a spectrum of cell size (including micromegakaryocytes) and a high degree of dysplasia 112461. Cases of RAEB·F may morphologically overlap acute paomveiosts with myelofibrosis (APMF) previously referred to as acute (malignant) myelofibrosis. APMF is dis- netfrom RAEB-F by its abrupt onset with 'ever and bone pain 11651, 22251. Irrmunophenotype Flow cytometry in RAEB often shows increased numbers 01 cells positive for precursor cell associated antigens CD34 and/or C0117. These cell s are usually positive for C038. HLA-DR and myeloid- associated antigens CD13 and/or CD33. Asynchronous expression of granulocytic maturation antigens CD1S, C011b and/or COOS can be seen in the blast population. Aberrant expression 01C07 on blast cells is seen in 20% 01 cases and C056 is present in 10% of cases. while expression of other lymphoid markers is rare {1210. 1623J, In tissue sections, C034 immunohisto- chemistry may be used to confirm the presence of an increased number of blasts; it allows the appreciation of their arrangement into clusters or agg regates, a characteristic finding seen in most of the cases of RAEB 120501. Antibodies such as C061 or C042b can aid in the identification of micromegakaryocytes and other small dysplastic forms. which are particularly numerous in cases of RAEB-F 11246, 22261_ Genetics A variable percentage of cases of RAEB (30- 50%) have clonal cytogenetic abnor- malities, including +8, -5, del(5q). -7. del(7q) and del(2Oq). Complex karyo- types may also be observed 17821. Postulated cell of origin Haematopoietic stem cell. Prognosis and pl'edictive factors Refractory anaemia with excess blasts is usually characterized by progressive BM failure with increasing cytopenias. Ap- proximately 25% of cases 01 RAEB-l and 33% of patients with RAEB-2 progress to AML; the remainder succumb to the sequelae 01 BM failure. The mediansurvival is approximalely 16 months for RAEB-1 and 9 months for RAEB-2 17811. CD7 expression has been assocrateo with poor prognosis {16231. RAEB-2 patients with 5- 19% blasts in the PB have a median survival of 3 months similar to that of myelodysplasia-related AML 121t 41, In contrast, cases defined as AAEB-2 based only on the presence of Auer rods. have a prognosis which is similar to that seen in cases of RAEB-2 with 2-4% peripheral blasts (median sur- vival. 12 months) 121141. Refractory anaemia with excess blasts tOl
  • Myelodysplastic syndrome with isolated del(5q) Definition Mveiccvsoiasnc syndrome with isolated del(Sq) is a myelodysplastic syndrome (MDS) cnaractertzeo by anaemia with or without other cvtopenrasand/or thrombo- cytosis and in which the sole cytogenetic abnormality is del(Sq), Myeloblasts con- prise<5% of nucleatedbone marrow(8M) cells and <1% 01 peripheral blood (PSI leukocytes and Auer rods are absent. Synonym MyeIodyspIastic syndrome with 5Q deletion (Sq- syndrome). RP. Hasserjian MM LeBeau AF. li st J.M. Bennett J. Thiele ,. • ., EpidemK>logy MDS with isolated del(Sq) occurs more oflen In women, with a median age 0167 years. Etiology Presumed loss of a tumou r suppressor ge ne in the deleted regioo . Possible ca n- didates include the early growth response 1(EGR 1) and c-ceterm (CTNNA I) genes and as-vet-untcennted genets) in 5q32 1256, 1075, 1324). The RPS14 gene that encodes a ribosomal protein has been propo sed as a can didate in the Sq- syn- drome, raising the possibility that a defect in ribosomal protein function ca uses that disorder 1256. 635, 1075. 13241. Sites of involvement Blood and bone marrow, Clinicalleatures The most common symptoms are usually related to anaemia. whic h is often severe and usually macrocytic. Thrombocytosis is present in one third 10 one half of patients. while rnromcoocytopenle is uncommon {794, 14171. Mo<phology The BM is usually hypercellular or norma- cellular and frequently exhibits erythroid hypoplasia 123621. Megakaryocytes are increased in number and are normal to sfil.:t1tIydecreased in size withconspicuwsIy 102 MyelodysplastJc Syndromes non-lobated and hypolobated nuclei. In contrast, dysplasia in the erythroid and myeloid lineages is uncommon 1257. 794}. The term "Sq- syndrome- has been used to desi gnate a subset 01cases with macrocytic anaemia. normal or eleva ted platelet count and BM erythroid hypoplasia 1257,23621.The number of blasts in the BM is <5% and in the PB is < 1%. Genetics The sole cytogene tic abnormality involves an interstitial deletion 01 chromosome 5; the size of the deletion and the breakpoints are variabl e, but band s q31·q33 are invariably deleted. If any additional cyto- genetic abnormality is present (With the exception of a loss of the Y chromosome), the case should not be placed in this cat- eqoey 11 has bee n recen tly reported that a small subset of patients withisolated del(Sq) may show a concomitant JAK2 V617F mutation. Until more data are collected for such cases and theirclinical behaviour and response to therapy such as lenalidomide are clarified. it is prudent to classify lhem as MDSwith isolated de~5q) (rather than in the MDS/MPN category) and to note the pres- ence of the JAK2V617F in the diagnosis 110051. Postulated cell of origin Haernatoootetrc stern cell . FISH analysis has confi rmed presence of the del{Sq) abnormality in differentiating erythroid. myeloid. and megakaryocytic cells, but generally not in mature lymphoid cells 139.2191. Prognosis and predictive factors This disease is associated with a rrecen survival of 145 months, with transformatioo to acute myeloid leukaemia occurring II <10% of patients 17941. Patients with del(Sq) associated with other chrorTlOSlmll abnormalities or with excess blasts have an inferior survival and are excluded frOOI this diagnosis 17941. Recently. the thalia; mide analogue lena fidomide has been shown to benefit MDS patients with isolated del(Sq) as well as del(5q) with additional cytogenetic abnormalities. Transfusion independence was achieved in two thirds of patients and was c losely linked to suppression of the abno rmal clone (795, 13201
  • Myelodysplastic syndrome, unclassifiable Definition Myelodysplastic syndrome. unclassifiable (MDS-U) is a subtype 01 MDS which ini- t~1y lacks findings appropriate for classi- fication into any other MDS category Three possible situations which qualify patents tor inclusion in this category are listed under -morphology·. 9989/3 Sjrooym Uyelodysplastic syndrome, NOS. EpOdemk>logy The incidence of mvetodvscrasuc 5YO- cone. uoctassmame. is unknown. Sites of irwotvement The peripheral blood (PB) and bone mal1'C1W (8M)arethe principal sites of involvement. Clinicalfeatures Patients present with symptoms similar 10 nose seen in the other myetcovsprasnc syndromes. --There are no specific morphological lind- iogs. The diagnosis of myerocvsplasnc syndrome, unctasslnabie. can be made in the following instances: 1. Patients with the findings 01 refractory cytopenia with unilineage dysplasia (RCUO) or refractory cytopenia with rn.Jlti- lineage dysplasia (RCMD) but with 1% blasts in the P8 qualify for MDS-U 111651. 2.Casesof MOO with tXlihneage dySplasia which are associated with pancytopenia. In contrast. the RCUD category only allows for a single cytopenia or bi-cytoperna. 3. Patients with persistent cvtooemats) with 1% or fewer blasts in the blood and fewer than 5% in the BM, unequivocal dysplasia (Table 5.03) in less than 10% of the cells in one or more myeloid lineages. and who have cytogenetic abnormalities considered as presumptive evidence 01 MOO (Table 5.04) are placed in this category MDS-U patients should be carefully followed for evidence of evolution to a more specific MDS type. A.Orazi AD Brunning I. Baumann R.P. Hasserpan Genetics See Table 5.04. Postulated cell of origin Haematopoietic stem cell. Prognosis and predictive factors If characteristics of a specific subtype of MDS develop later in the course 01 the disease, the case should be reclassified accordingly. In cases diagnosed as MOS. U. it is unknown both the percentage 01 patients which translorm to acute myeloid leukaemia as well as the disease survival . Cases with features otherwise consistent WIth a diagnosis 01 RCUD Of ACMO. but in which 1% blasts are detected in the peri- pheral blood, have been shown to have a prognosis which is intermediate between ACUO (or ACMO) and that of refractory anaemia with excess blasts (AAEB) 11 1651. Myelodysptasttc syndrome. unclaSSiflable t03
  • Childhood myelodysplastic syndrome I. Baumann C,M. Niemeyer J .M, Bennett K. Shannon Table 5.06 Ir.cKIence ofhaematoklgical malignancies in children 0 - 14 years, Combined data from Dtlnmark. 1980-1991and British Columbia 1982-1996(907, 908}. ALl.acute IyrnpIlobIaSbC leukaemia;AML.acute myeloid leukaemia; MOS, ~SbC s)'l'klrome; JMML,;.wetiIe m~ leukaemia:CUl. etworic myelogenous leukaemia. PII. poIytytllaeITia vera;El essenbal ttvorrtlocyII'I , ExdudngDown 5)'I»'ome (OS) I pern-.on poptAalJon peryear Myelodysplastic syndrome CMOS) is very UflCOrTlfl"lOf1 in children, accounting lor less than 5% of all haematcooenc neoplasms in patients less than 14 years of age (Table 5.06) 1908. 910 , 1595A, 2079AI. The de novo or primary form of MDS in children should be distinguished from cases of "secondary MOS· that follow congenital or acquired bone marrow (8M) failure syndromes and from therapy· related MDS that tollows cytotoxic therapy tora previous neoplastic or rco-reootastc condi tion. Furthermore. although MOS associated with Down syndrome has been reported to account lor 20-25% 01 cases of childhood MDS in the past {2079AI, this disorder is now considered as a unique biologic entity synonymous with Down syndrome-related myeloid leukaemia and cnstmct from other cases of chil dhood MDS (See Chapter 6). Many of the morphologic. immonopheno- typic and genetic features observed in MDS in adults are also seen in childhood forms of the disease but there are some signifi- cant differences reported , part icularly in patients who do not have increased blasts in their peripheral blood (PB) or 998513ICD-{) code Epidemkllogy RCCis the most corrmon subtype 01 MDS in childhood accounting for about 50%ct Definition Refractory cytopenia of childhoocl (RCC}1S a mveioovsotastc syndrome (MDSl char· actenzeo by persistent cytopenia with <5% blasts in the BM and <2% blasts in the PB {908). Although the presence of dysplasia is required for the diagnosis, the cytological evaluation of dysplasia by itself constitutes only one aspect of the morpho logical diag- nosis of RCC, The evaluation of an ade- quate BM trephine biopsy specimen is indispensable for the diagnosis 01 RCe in children, About 75% of children with RCe show considerable hypocellularity 01the BM 117841. Consequently, it may be very cha llengin g to differentiate hypocellular RCC from other BM failure disorders, es- pecially from acquired aplastic anaere and inherited BM failure disorders. Down syndrome-related myeloid neoplasms are excluded from this diagnosis. The WHO Working Group assigned RCC to a groop of provisional entities. Refractory cytopenia of childhood (RCC) Synonym Refractory anaemia of childhood. •~IQ . 5J l Relractory~dd'ikhxld(RCC~_ marrow smear showing abnormal nuclear IctUabcwl d antwyttYopoietIc precursor eel alld a smaI megaQ"r- ocyle WItIl a IJi.lobed 1IUdeus, BM. For example, the subtypes 01 refractory anaemia with ring stoeroblaets and MDS associated with isolated del (Sq) chromo- somal abnormality are exceedingly rare in chil dren 11595A1. Isolated anaemia, which is the major presenting rnamtestatton of refractory anaemia (RA) in adults, is un- COlTIllOO in chil dren, wto are more likely to present with neutropenia and thrombo- cytopenia 1908, 11091. In addition, hypo- cellularity of the BM is more commonly observed in childhood MDS than in older patients. Therefore, some chi ldren have findings that do not readily fit into the "low grade" MDS categories. To address these differences, a provisional entity, refractory cytopenia of childhood (RCC) is intro- duced and defined below. For children with MOS in whom there are 2-19% blasts in the PB or 5-19% blasts in the BM . the same criteria utilized for adults with refractory anaemia with excess blasts (RAEB) should be applied . Currently, in contrast to adult MOS, there are no avail- able studies that have investigated the prognos1ic significance of distinguishing RAEB-1 and RAEB-2 in chil dren, but it is recommended that this distinction be made for future investigation. Children with RAEB generally have relatively stable PB counts for weeks or months, Some cases diagnosed in children as acute myeloid leukaem ia (AML) with 20-29% blasts in the PB and/or BM that have myelodysplasia- related changes. including cases with myelodysplasia-related cytogenetic ab- normalities (See Chapter 6) may also have slowly progressive d isease. These cases, considered as refractory anaemia with excess blasts in transformation in the French-American -British cooperative clas- sification. may lack the clinical features of acute leukaemia and behave more like MOS than AML 19081. thus follow-up PB and BM studies are often necessary to measure the pace of the disease in such cases. Children who present with a PB and/or BM disorder associated with t(8;21)(q22;q22), inv( 16)(p13.1q22) or t(16; 16XP13.1;q22) or t( 15;17Xq22;q 12) should be considered to have AML re- gardless of the blast count % Incidence' 79 38.5 11 5.4 4 1.8 2 0.9 2 1,2 1 0,6 o 0.1 o 0.1 1031 100 48.1T"," N AU 915 AMl1 115 "lOS' 38 Myebd leuk.aemia of OS 19 JMMl 25 CMl 13 'VIET 3 Unclassified 3 104 Myelodysplastic syndromes
  • Etiology The etiology is unknown in most cases. ire cases 11704, 1784/. II is diagnosed in all age groups and affects boys and girls with equal frequency 111091. Stesof involvement Bloodand 8 M are always affected. Gen- efally. spleen. liver and lymph nodes are rot sites of initial ma nifestation. Megakaryopoiesis Unequivocal micromegakaryocytes, othefdysplasticchangesl invariable numbers UnequiYocal micromegakaryocytes: irnrl'lJnohistoctlemistry is obIigab')' (COOl , CD41 ). oltlerdysplasti: cIIange5t ill variable I1lSI1bers cytoplasm may be noted . Blasts are absent or account for less than 2% of the white blood cells . On 8M aspirate smears dysplastic changes should be present in twoditlerent myeloid cell lineages, or exceed 10% in one single cell line (Table 5.07). Erythroid abnormalities include nuc lear budding, mcmnucreanty karyorrhexis, internuclear bridg ing. cytoplasmic granules and macr0- cvnc Changes . Cells of granulocytic line- age may extubtt hyposegmentation with pseudo-Pelqer-Huet nuclei . hypo-fagran- ularity of the cytoplasm, macrocytic (giant) bands and cytoplasmic-nuclear maturation asynchrony. Myeloblasts account lex" fewer than 5% of the 8M cells. Megakaryocytes are usually absent or very low in nt.rnber. The detection of micromegakaryocytes is a strong ind icator 01 RCC . Ring sioero- blasts are not found . In RCC with norma- Of hypercetlular 8M specimens there is slight to moderate increase of erythropoiesis with accumula- tion of immature precursor cells. mainly proerymrootaste. Increased numbers of mitoses indicate ineffective erythro- poiesis. Granu lopoiesis appears slightly 10 moderately decreased and cells of granulocytic lineage are loosely scat- tered. Blasts account for less than 5% of the 8 M cells, and C034 staining on the biopsy is useful for verification of the blast percentage. Megakaryocytes may be nor· mal, decreased Of increased in number and display dys plasia with non-lobulated nuclei. abnorma lly separated nuclear Nominimal diagnostic cmeria Granulopoiesis Dysplasbc changes" inat 18ast10%of granulocytic precursors and neutrophils: <5%blasts Dysplastic changes' nat I8ast10%ofneutrophis; "".... Erythropoiesis Dysplasticchanges' andlormegaloblastoid changes inat least 10% of erytlroidPfeoJ~ Alewdusttl'Sofatleast20 erythroid precursors. Stoll inmaturatiOn with increased numbers of 1''''0'''''''''''lncmased I1UIT'tlers ofmitoses. Bonemarrow biopsy Bone marrow aspirate Peripheral blood •AbnormaII'IIdear lobulation, mutIirKIdear oeh.I'lUdear bfidge$. rPseu:Io-PeIger-HlJiiteels. tlypo-or agrardanly, IJ'if'l b8rlds(Incasesofsevere neutropenia lI'»s crilena may nol be fuIIiIed ). f Megakaryocytes ofvanabIe see WIttl $&p8r31ed nuclei orround IlI,dei.Theabsence ofmegak¥yIX:yIes"not emude refraclofy C)'IOPel'Iia ofchitJlood. Morphology The classical picture of RCC is a PB smear that shows red blood cell antsopolknocytosts and macrocytosis. Anisochromia may be present. Platelets often display anisocytosis and occasion- ally giant platelets can be detected. Neutropenia wit h pseudc-Pelg er-t-luet nuclei and/or hypogranularity of neutrophil Table 5.07 Minimal diagnosticcriteria forreffactory cytopenia ofchildhood. 1-'..~ ., • ./ < , ..f •~ • . I ....~ •'~ Clinical features The most common symptoms are malaise, bleeding, fever and infection /1109). lym- phadenopathy secondary to local or systemic infection may be present, but hepatosplenomegaly is ge nerally not a feature of RCe , In up to 20% of patients, eocjrucal signs Of symptoms are reported 11 109/. Congenital abnormalitiesof differ- ent organ systems may be present. Three Quarters of patients have a platelet count below 150x109/L. whi le anaemia with a haemoglobin concentration 01less than 10 g/dL is noted in aboul half of the affected children 111091. Macrocytosis of fed cells evaluated according to the patient's age is seen in most The wh ite blood count is generally decreased with severe neutropenia noted in about 25% 111091. Childhood myeocvsotasuc svocrore 105
  • thereby mimicking RCC (Table 5.09). In the absence of a cytogenetic markerthe clinical course of cases suspected lX RCC has to be carefully evaluated before a clear-cut diagnosis can be made. rte haematological differential diagnosis .... ciuoes acquired aplastic anaemia. riter· ited 8M failure diseases and paroxysrral nocturnal haemoglobinuria (PNH). Inceo- trast to RCe. acquired aplastic aneere presents with adipocytosis of the 8M spaces with few scattered myeloid cells there are no erythroid islands wllh increased numbers of immature erythro- blasts, no granulocytic dysplasia and no micromegakaryocytes (Table 5.08).CO'< trary townatis sometimesreported in adUls with aplastic anaemia, at presentation acquired aplastic anaemia of childhood does not have megaloblastic features; IQl. lowing immunosuppressive therapy, the histological pattern of acquired apiasic anaemia can no longer be separatedfnm that observed in RCC. The inherited au failure oeoroers such as Fanconiereera ovskeratosrs conqemta . Shwachmar- Diamond syndrome, amegakaryocytC thrombocytopenia or pancytopenia radioulnar synostosis show overlap morphological features with ACC, They have to be excluded by medical hisl~ phySical exemoanooand the appropraale laboratory and molecular studies belen a definite diagnosis of RCC can be made The clinical picture of PNH is rare in C/"Ml(j. hood. although PNH clones in the ab- sence of naemoivsts or thrombosis may be observed in children with RCe 122921 The relation between RCe with two (It" more dysplastic lineag es and retractor cytopen ia with mu llilineag e dysplasia (RCMD) has not vet been evaluated, Currently il is recommended that children who otherwise fit the criteria for RCMD be considered as RCC until such studies clarify whether the number 01 lineages involved is an important prococsc discriminator in childhood MOS. Immunophenolype Mlcromegakaryocytes can be missec easily in H&E stained 8M trephine biopsy sectcos but can be more readily awe- ciated by the expression 01 platelet g/y(» proteins like C061 (glycoprotein lila),C04I (glycoprotein lib/lila) or von Willebrancl factor. Myeloblasts do not account ta more than 5% of the 8 M cells , and oetec- tton of 5% or more CD34, mvetooeroe dase, lysozyme and CD117 positive biaS! May be increased BoN tIJafJDW' ISpI(BIe~ lICkflg or Y8IY leweels, WIthool. dysplasiaor megalobIastlid change Maybe increased M~ MulI~e separated nuclei Small roundnuclei lbIe .C)'tc*lgy --.......,..." --~-­Agranuiabon ofcytoplasm_d_Ni.dear<ytoplasmlc malurabondefects Differentialdiagnosis In children, a variety 01 non-haematological d isorders such as viral mtecuons. nutri- tional deficiencies and metabolic diseases can give rise to secondary myelodysplasia, establis hing the diagnosis, Multiple sec- tions prepared from the biopsy may be helpful in roermtcanoo of abnormal rneqa- karvocytes and immunohistochemistry to identify mictomegakaryocytes is obligatory. Fatty tissue between the areas of haemato- poiesis can mimic aplastic anaemia (Table5.08). Thereforeat least two biopsies at least two weeks apart are recom- mended to facil itate the detection of representative 8M spaces containing foci of erythropoiesis. Noincrease Markeddea8ase Dysplastic manges Miaomegakaryocytes May be increased focally or dispersed Noincrease l.Icting orsingle smaIbcus WlIh Ie5slhat110cels W11tl --I.JIc:UIg or ~ decrease, Y8IY lewsmalloci 'NIth maturation l.adUng orY8IY few,no dysplastlc - Pattry dcstrtluIion lell shift -- May be increased bcally Of -"" Aplastic lNemia in childhood C034+cells Lymphocytes C034+cells bbl, 5.08 ComparisonOf rnlIIphologicaI cnlefiaaIhypoplastic refracby cytopeoiaofchildhood and aplasticanaemia inchildhood R,1ractofy cytopenil of childhood lobes and characteristic micromegaKaryo- cytes. There is no increase in reticulin fibres. The majority of patients with RCC show a marked decrease of 8M cellularity, down 10 5-10% of the normal age matched veroe. The morphologic findings are sim- ilar to those observed in the normally cellular Of hypercetlular cases. Immature erythroid precursors form one or several islands consisting 01 at least 10 cells . This patchy pattern of evtreoooests is usually accompanied by sparsely distributed granulopoiesis. MegaKaryocytes are sig. nilicantly decreased or absent. Although micromeqakaryocvtes may be rare or not always found, they should be searched lor carefully as they are impo rtant in 106 Myelodysplastic syndromes
  • Table 5.09 Dfsofders which maypresent witll morphojogic.alleal~ res indisbnguishablefrom refractory cytopenia ofct1ildhood, Infectioos (e.g,c:ytomeo;lalovirus, herpes Wuses.parvovirus 819, YiscerailelsnmaniasiS) Vrtamin detiOeocy (e,g.deficiency ofvitamin B12,Iolale, Yilamln E) Metabolic: disorders(e.g,mevalonatemase delk:iency) Rhel.maliC disease A.utoirmuIeI)mphoproIIferative dISOrders (e,g, FASdeftciency) Mllochondrial deleloos(Pear9onS)YIdrome) ~ bone marrow laikJre disorders(e,g Fanconi anaema. dyskeratosis congeniIa, 5hwactmam-Oiarnond syndrome, amegakaryocyIit~,1hrorTtlocytope WI1h absent radii, radioulnar syMSlO$lS. Sedtelsyndrome) P~nochrnaI ~ (PM-I) ~ apIasbcanaemia dlmg haemalologicall'llCOYllfy cells may lncncate progression to high grade MOS. Clusters of myeloblasts are -otseen in ACC. Genetics The genetic changes predisposing to !.lOS in childhood remain largely obscure. The presumed underlying mechanism may also give rise 10 subtle phenotypic abnormalihes noted in many children with MOS. Monosomy 7 is the most common cytogenetic abnormality /1 109, 1704, 17841. Other cytogenetic abnormalities IlChJding complex karyotypes may also beobserved. Most cases of ACC show a rnmal karyotype irrespective 01 8M eel- ltarrty. There is no difference in morpho- lOgy between cases with Of without -oonosomy 7. PtlstuIated cell of origin saematopoenc stem celt with multihn- eage potential , Prognosis and pred ictive factors (aryotype is the most important factor 'or progression 10 advanced MOS. Pa- tents with monosomy 7 have a sign ifi- cantly higher probability of progression fanpatients with other chromosomal ab- rcmannes or normal karyotype 111091. Spontaneous disappearance of mono- somy 7 and cytopenia has been reported in infants, but remains a rare event It3801. In contrast to mooosomy 7, patients with trisomy 8 Of normal karyotype may expe- riencea long stablecourseof theirdisease, Currently, haematopoietic stem cell trans- plantation (HSCT) is the only curative therapy and is the treatment of choice for patients with monosomy 7 or complex karyotypes early in the course of their dis- ease . In view of a low transplant-related mortality HSCTcan also be recorsrenoed for patients with other karyotypes if a SUIt· able donor is available /1784 . 21041. An expectant approach with careful ob- servation may be reasonable for patients in the absence of transfusionrequirements. severe cytopenia Of infections. Because early 8M failure can at least in part be me- diated by t-een immunosuppression of baenatoooese. irrmunosuppressive ther- apy can be a successful therapy strategy for improving outlook in some children with ACC 12033, 24711. Childhood myelodysplastlc syndrome 107
  • CHAPTER 6 Acute Myeloid Leukaemia and Related Precursor Neoplasms Acute myefoid leukaemia with recurrent genetic abnormalities Acute myeloid leukaemia with myelodysplasia-related changes lllerapy-related myeloid neoplasms Acute myeloid leukaemia, not otherwise specified Myeloid sarcoma Myeloid proliferations related to Down syndrome Blastic plasmacytoid dendritic cell neoplasm
  • Acute myeloid leukaemia with recurrent genetic abnormalities D.A, Arber R D, Brunning M.M.le Beau B, Falini J.w. Vardima~ A. POrNIt J. Thiele CD. Bloomfield AML with balanced translocations/inversions Acute myeloid leukaemia with t(8;21)(q22;q22); RUNX1· RUNX1T1 Fig. 6.02 Myeloid sarcoma Biopsy ofan orbitaIl'I'IaSl froma childw;thAML witha ~ a;21)(q22;q22). There in eosinoph~ precursors scattered in!he preOominat1l lNs1 poplIlation. FIg.lOl /IoI/IIl myeloid IeUlaen'ia Wlltl .811XQ22:Q22' Bone marrow tllasts s/'lowirlg abl.n:lant pUr qtIpIasm WIlh ~deari'1g em Wge~ ......... Immunophenotype Most cases of AMl with the (8;21 )(q22;q22) translocation disp lay a characteristc immunophenotype with a subpopulatioo of blas t cells showing high intensity ex- pression of CD34, together with HLA-DR, myercoeroxidase (MPO) and CD13. bJ relatively weak expression of CD33j114Q, 17751. There are usually signs of granulo- cytic differentiation with subpopuianonsd cells showing granulocytic rnaiuranco demonstrated by CD15 and/or COO expression. Sometimes populations cI blasts showing maturation asynchrony are present (e.g. co-expressing COOt and CD15 ). These leukaemias frequen express the lymphoid markers CD19 and PAX5, and may express cvtoptasrre CD79a 1996, 1155. 2236} . Some cases are terminal deoxynucleotidyf transferase (TdT) positive; however, TdT exoresscoe Clinical features Tumour manifestations , such as myeloid sarconas.may be present at presentation . In such cases the initial bone marrow (BM) aspiration may show a misleading low number of blast cells. but should be diagnosed as AMl despite a blast per- centage in the BM of <20, Epidemiology The t(8;21)(q22;q22) is found in -5% of cases of AMl and in 10%01the prior acute myeloblast ic leukaemia with matu ration (M2) category of the French-American- British classification. It occurs predomi- nantly in younger pat ients. Morphology and cytochemistry The common morphological features in- clude the presence of large blasts with abundant basophilic cytoplasm, often containing numerous azurophilic granules and perinuclear clearing or bots. A few blasts in many cases show very large gra nules (pseudo-Chedrak-Hiqashi gran- ules), suggesting abnormal fusion . Auer rods are frequently found and appear as a sing le long and sharp rod with tap ered ends; they may be de tected in mature neutrophns. In addition to the large blast cells, some smalle r blasts, predominantly in the peripheral blood (PBj, may be found. Promyerocvtes, myeiocytes and mature neutrophils with var iab le dy splasia are present in the BM. These ce lls may show abnormal nuc lear segmentation (e.q. pse uoo-Pelqer-Hoet nuc lei) and/or cyto- plas mic staining abnormalities, including homogeneous pink coloured cytoplasm in neutrophil s. Dysplasia of othe r Cell lines, however, is uncommon. Eosinophil precut- sees arefrequently increased. but they do not exhibit the cytological or cytochemical ab- normalitiescharacteristicofAMl associated with ab normalities of chromosome 16: basophils and/or mast cells are sometimes present in excess.A monocytiCcomponent is usually minimal or absent. Erythroblasts and meg akaryocytes are morphologically normal. Rare cases with a BM blast per- centage <20 occur, These should be classified as AMl and not as MOS. 9896/3 This group is characterized by recurrent genetic abnormalities of prognostIC signif- icance. The most commonty identified are balanced abnormalities: 1(8;21)(q22:q22), inv(16)(p 13. l q22) orI(16:16)(p 13.' ;q 22), 1(15;17}(q22;q12) and 1(9.11)(p22;q23) 1306. 721, 848 , 20361. Each 01 these structural chromosome rearrangements creates a fusion gene encoding a chi- maeric protein that is required. but usually not sufficient. for leukaemogenesis 120631. Many of these disease groups have char- acteristic morphological and immuno- phenotypic features 1651. The categories of acu te myeloid leukaemia (AML) with 1(8:21)(q22:q22), iov( 16)(p 13.1q22) or 1(16:16)(p 13.1;q22) or l(lS;17)(q22:q12) are considered as acute reukaermas without regard to blast cell cou nt. It is not yet clear if all cases with t(9;11Xp22;q23), t(6;9)(p 23;q34 ). inv(3)(q2 1q26,2), t(3;3) (q21;q26 2) or t( 1;22)(p 13;q13) should be categorized as AMl when the blast cell count is <20%. Many of the translocations are detected by AT-PCA which has a higher sensitivity (1x10"5) than cytogenetic analysis (1x 10-2). Cases of therapy-related AMUmyelodyspla stic syndrome (MDS) may also have the balanced translocations and invers ions that are described in this section, but these should be diagnosed as therapy-related AMUMDS with the associated genetic abnormality noted. ICD-Ocode Definition Acu te myeloid leukaemia. with t(8;21) (q22;q22); RUNX1-RUNX7T1 is an AMl generally showing maturation in the neutro- phil lineage. 110 Acute rnyelord leukaemia and related precursor neoplasms
  • Synonym Acute myeloid leukaemia with abnormal marrow-eosoconns. Acute myeloid leukaemia with inv(16)(pI3.1q22) or t(16;16)(pI3.1;q22); CBFB· MYH11 Epidemiology Either inv(1 6)(p 13.1q22) or t(16;16) (p13. 1;q22) is found in 5-8% of all cases of AML. They can occur in all age groups but are found predominantly in younger patients. Fig. 6.04 Acu1e myeloid leukaemia with associated inv(16Kp13.1q22). AbnonnaI eosi~ . one VIlth Large basophiliccolouredgranules.aAl present Clinical features Myeloid sarcomas may be present at initial diagnosis or at relapse and may constitute the only evidence of relapse in some patients. Morphology and cytochemistry In these cases. in addition to the usual morphological features of acute myelo- monocytic leukaemia, the 8M shows a variable number of eosinophils (usually in- creased. but soretrres <5%) at all stages 01 rretoratco without significant maturation arrest. The most striking aboomantee in- volve the immature eosinophilic granules. mainly evident at the promyelocyte and myelocyte stages . The abnormalities are usually not present at later stages of eosinophil maturation . The eosinophilic granules are often larger than mose nor- mally present in immature eosmocnus. purple-violet in colour, and in some cells are so dense that they obscure the cell 9871/3 good response to chemotherapy and a high com plete remission rate with long- term d isease-free survival when treated with high dose cytaratnne in the consoli- dation phase 1228. 8481. Some factors appear to adversely affect prognosis including C056 expression aOO the pres- ence of KfTmutations 1123. 16961. ICD-O code Definition Ac ute myeloid leukaemia with inv(16) (p13.1q22) or t(16:16)(p13,1:q22); CBFB- MYH11 is an AML that usually shows monocytic and granulocytic differentiation and characteristically abnormal eosinophil component in the BM {1258. 1393, 20631. generally weak. C056 is expresse d in a fraction of cases and may have adverse prognostic significance {1231· Genetics The genes for both reteroosreoc compo- nents of core bindll)Q lactor (CBF), RUNX I (atso known as AML 1or CBFA) aOO CBFB ere involved in rearrangements associated WIth acute reukaemes {20631. The t(8;21) (Q22;q22) involves the RUNXI gene, which encodes core- bindin g factor subunit alpha and the RUNX 1T1(ETO) gene {608, 1294, 17331. The RUNX1-RUNX1T1 fu- sion transcript is consistently detected in patients with 1(8;21)(q22;q22) AML. The CBF transcription factor is essential for baematopolests. and transformation by RUNX1-RUNX 1T1 likely results from tran- scriptional repression of normal RUNX1 target genes via aberrant recr uitment of nuclear transcriptional co-repressor com- plexes. Over 70% 01patients show aooi- IIQll3Ichromosome abnormalities: e.q. loss rJa sex chromosome or del(9q ) with loss rJ 9Q22. Secondary cooperating mutations rJ KRAS or NRAS are common (30%) in caedtamc CBF·associated leukaemias ~l. Mutations of KIT occur in 20-25% 01 cases (16961. Postulated normal cout erpart Myeloid stem cell wilhpredominant reuno- phil differentiation. Prognosis and predictive factors Acute myeloid leukaemia with t(8;21) (q22;q22) is usually associated with a 16 inv(16) • • I--<> XI --<> • • .. 16 inv(16) :~:>: A Fig. 1.03 Acute myeloid leukaemia withinv(16)(pt 3.1q22). A The inversion 16 results from breakage and rejoining of bands 16p13.1 and 1&;22. G-banded normal (nI) linrTIosome 16 and irW(16)areshown. B Dual rolorftUOfllSC6OC6 insituhybridizalion: !he5'regll)llofCBFB islabeled inred; !he3' regioninpen Anonnal ettromosome 16 has ~ 5'and 3' regions ~ 10 e<lch otherresultioginasiogle yellowOf oveOappiog IlldIgreen signals,Theinvefsion 16splits theCBFB locus resulting inseparalered andgreen sigla/$. 80Itl interphase ooIIs have one normal 16etvomosome andoneinv(16), Acute myeloid leukaemia with recurrent genetic abnormalities 11 1
  • • Synonym AMl with 1(15;17)(q22;qt2). Acutepromyelocytic leukBemia with t(15;17)(q22;qI2); PML-RARA Epidemiology Acute promyelocyte leukaemia comprises 5-8% of AMl {20781. The disease can occur at any age but patients are pre- dominantly adults in mid-life. 986613ICD-O code ~ B Fig. '.05 Acute promyeIocybc leukaema. A~ ~ typenbonemarrow smear.Theftwe IM'i abnormalprornyelocyles wilhITIense amq:hIc,..... lam. Sewr1lI ollhe promyeIocyles oontaillUl-.all Auef rods(Iaggot oeIs). B M~ vWrt. 1'1 Pt- ripheral bloocI smear. There are several abnclmll promyelocy!es 'Mthlobl,Jlaled. almostc:eretlnbm ru:Il The cytoplasm coolains numerous small alI.tllPl* granules: other ~Is appear sparsely ganlMr. Definition Acute promyelocytic leukaemia (API. or AML with t(15;17)(q22;q12)J is anAMLII which abnormal promyelocytes predcm- nate. 8cttl hypergrarUar'or"l'ypil:3" APLcnl microgranular (hypogranular) types emt Clinical features Typical and rricrograrlAar API.. are lrequerty associated with disseminated inlravasoJa' coagulation (DIG). In microgranular API.. unlike typical API.., the leukocyte COlJ'lt IS very high, with a rapid doubling time Postulated normal counterpart Haemetcooiencstem cell with potential to differentiate into granulocytic and mono- cytic lineages . fusion of the CBFB gene at 16q22 to the MYH11 gene at 16p 13.1 120061. MYH11 codes for a smooth muscle myosin heavy chain 15061. The CBFB gene codes for the core binding factor (CBF) beta sub- unit, a heterodimeric transcription tactoe known to bind the enhancers of t-een receptor (TCR). Cylokine genes, and other genes. The CBFB subunit heterodimerises with CBFA, the gene product of RUNXl, one of the genes involved in AMl with t(8;21)(q22;q22). Occasionally cytological features of AMl with abnormal eosropnns may be present without karyotypic evi- dence of a chromosome 16 abnormality, the CBFB-MYH 11 being nevertheless demonstrated by molecular genetic studies (1533, 1882) By conventional cytogenetic ana lysis, the inv(1 6)(p1 3,lq22l/t(16:16) (p1 3,1;q22) is a subtle rearrangement that may be overlooked when metaphase preparations are suboptimal. Thus, at dia gnosis, the use 01FISH and RT-PeR methods may be necessary to document the genetic alteration. Secondary cytoge- netic abnormalities occur in approximately 40% of cases, with +22, +8 (10 -15% each), and del(7q) or +21(-5%) most commonly observed 113901.Trisomy22 is fairtyspecific for inv( l6XPl3.lq22) patients. being very rarely detected with other pri- mary aberrations in AMl. whereas +8 is commonly seen in patients with other prt- mary aberrations. Rare cases of AML and chronic myelogenous leukaemia with both inv(16)(p 13,1q22) and t(9:22)(q34:q1 l.2) have been reported, and this findi ng in chronic myelogenous leukaemia is usually associated with accelerated or blast phase of the disease 12454 J Mutations of KIT occur in approximately 30% ofcases 116961. Prognosisand predictive factors Clinical studies have shown that patients withAMl withinv(16)(p13 .1q22) or 1(16;16) (p13.1;q22) achieve longer complete remissions when treated with high dose cytarabine in the consolidation phase 1848, 15301. j-owever.older patients have dec reased survival and those with KIT mutat ions have a higher risk of relapse and worse survival 1546. 16961. Patients with +22 as a secondary abnormality have bee n reported to have improved outcome 11390. 19621. morpho~y. The mature eosinophils may occasionally show nuclear hyposegmen- lal ion. The naphthol-ASD-chloroacelale esterase reaction. which is normally negative ineosinophils, ischaractenstically faintly pos.tive in these abnormal eosmo- phils. Such a reaction is 001 seenin eoero- phils 01 AML with the 1(8;21)(q22;q22). Auer rods may be observed in myelo- blasts. At least 3% of the blasts show mveioperoxioase (MPO) reactivity. The monoblasts and promonocvtes usually show non-speci fic esterase reactivity, although it may be weaker than expected or even absent in some cases. In ad dition 10the predominant monocytic and eosino- ph il compo nents, the neutroph ils in the 8M are usually sparse, with a decreased number of mature neutrcphils . The PB is not different from other cases of acute mveromonccvnc leukaemia; eosinoobus are not usually increased. but an occa- sional case has been reported with ab- normal and increased eosinophils in the PB. While the majority of cases 0' inv( l6)(p13.1Q22)have been identified as having abnormal eosinophils, in some cases they are rare and difficult to lind . Occasooar cases with this genetic ab- normality lack the eosinophilia or show cxty myeloid mansatcn wilhoula I"ro"lOCytic CCJITlX)IlE!lll or only rro-ocvtcdifferentiation. Notinfrequently,the blast percentage is only at the threshold level0120%or oc:casionally lower. Cases with inv( l6)(p13.1 q22) or t(16; 16):(p l3. l ;q22) and less than 20% 8M blasts should be diagnosed as AML. The BM treph ine biop sy is usually hyper- ce llular, but may occasionally be normo- ce llular. Immunophenotype Most of these leukaemias are character- ized by a complex immunophenotype with the presence of multiple blast populations: immature blasts with high CD34 and CD l 17 expression and populations dif- ferentiating toward s granulocytic (CD13, CD33. CD l5. CD65. MPO positive) and monocytic (CD 14. CD4. CDl 1b. cone. CD64. CD36 and lysozyme positive) line- ages Maturation async hrony is often seen.Co-expression 01CD2 with myeloid markers has been frequently documented but It is not specmc for this diagnosis. Genetics The inv( 16)(p 13,1q22) foun d in the vast majority of this subtype and the less com- mon t(16; 16)(p13, 1:q22) both result in the 112 Acute myeloid leukaemia and related precursor neoplasms
  • 17 I I 15 1(15;17XQ22;Q12) d.~15)nl 15 A ~ U16 AcuIe prorll)'8locybc Ieuilaen'U WIIh 1(15;11Mq22;q12), ATheD'lslocabon 15;11 t'&SUts from br9akage a'ldr-.nion ofbands15q22 a'ld11q12.G-bMded normallnl) 15 11117dY::Jnc:lsanes (Ieft.l a'ldthe derivatNe ldetl 151n:l11 reslAng from eeIransIocation are sIlOWl'I on hi fil1C. BOuaIlDorl'unscence" sill hybtidiZ.alion M1h probes Pf.C. l'~ iIl'lll RARA(17ql2) derroostrate thepresence ofa Pl.UWtA.lusion ~ from the15;11 transIoca1o'l. Eactlofhi fw'eeIlBphase eels has one sep;nte red(PK) J9W.(W'II sepataIe ween (RARA) sigIaI,In:l one 'dOw or~ ~greet1 si!r.aI ronsislenl..,1Il1tle pttl5etIC8 ofaPMJRARA gene Iusioo. IbphoIogy and cytochemistry The nuclear size and shape in the aboor- rrel promyelocytes of hypergranular APL ere irregular and greatly variable; they are ::tten kidney-shaped or bilobed. The cyto- plasm is marked by densely-packed or even coalescent large granules, staining :Yight pink, red or purple in Romanowsky stains. The cytoplasmic granules may be solarge andior numerous that they totally rescore the nuclear cytoplasmic margin. In some cells. the cytoplasm is filled with Iredust-likegranules. Characteristic cells containing bundles of Auer rods ("faggot cells") randomly distributed in the cyto- plasm are present in most cases, Myelo- blasts with single Auer rods may also be Observed, Auer rod s in hypergranular APL are usually larger than in other types rJ. AMLand they may have a characteristic rrorphology at the ultras truct ural leve l '.vith a hexagonal arrangement of tubular structures with a specific periodicity of aeoroxrnaterv 250 mm in contrast to the 6-20laminar periodicity of Auer rods in erertypes of AML. The MPO reaction is always strongly positive in all the exaernc oromyeiocvtes. with the reac- tion product covering the entire cytoplasm l"Id often the nucleus. The non-specific esterase reaction is weakly positive in ao- ;>rQximately 25% of cases. Only occa- SJOnaI obvious leukaemic prooweiocvtes may be observed in the PB. Cases of rracrcqranurar (hypogranular) A.PI. arecharacterized by distinct morpho- QJicaI features such as apparent paucity CJ absence of granules. and predomi- I'lafltly bilobed nuclear shape 18111. The apparent hypogranular cytoplasm relates to the submicroscopic size of the azurophilic granules. This may cause c0n- fusion with acute monocytic leukaemia on Romanowsky stained smears; however, a small number of the abnormal promyelo- cvtes showing clearly visible granules and/or bundles of Auer rods (faggot cells) can be identified in many cases. The leukoc yte count is frequently markedly elevated in the microgranular variant of APL with numerous abnormal mcroqran- ular promy elocytes in contrast to typical APL. The MPO reaction is strongly positive contrasting with the weak or negative reac- tion in monocytes. Abnormal promveocytes with deeply basophilic cytoplasm have been described mainly in the relapse phase in patients who have been previ- ously treated with all-trans rettnoic acid (ATRA), The 8M biopsy is usually hyper- cellular, The abnormal promyelocytes have relatively abundant cytoplasm with numer- ous granules: occasionally Auer rods may be identified in well-prepared specimens. The nuclei are frequently convoluted Immunophenotype Acute promvetocvtrc leukaemia with the t( 15;17)(q22;q 12) (hypergranular or "typ- ical" variant) is characterized by low expression or absence of HLA·DR. CD34. leukocyte integrins CD11a, CD 11band CD18. a homogeneous, bright expression of CD33, and heterogeneous expression of CD13_ Many cases show expression of CD117, although sometimes weak. The granulocytic differentiation markers C015 and COO5 are negative Of only weakly expressed 11654.1678} and CD64 expression is common. In cases with microgranular morphology or cera Iran. script of the PML-RARA fusion gene there is frequent expression of CD34 and C02, at least on a fraction of cells 16531. Ap- proximately 20% of APl cases express C056. which has been associated with a worse outcome 16901· Using enrourocvto- Chemistry, antibodies against the PML gene product show a characteristic nu- clear multigranular pattern with nucleolar exclusion, in contrast to the speckled rela- tively large nuclear bodies seen in normal oromverocvtes or blasts from other types of AML (6621. Genetics In addition to its therapeutic impact, the sensi tivity of APL cells to ATRA has led to the discovery that the retinoic acid receptor alpha (RARA) gene on 17q12 fuses with a nuclear regulatory factor gene on 15q22 Fig. 1.07 Aone promyeIocytic Ieukaema. Bone IIIiWTtIW biopsy. Abnormal prorrt)'eIotyIe wilIl abl.ndal'll hyper. gran,Aated cytlpIasm. Thenudei are genefaIylWId tI oval. SewlraI of!tie nudei llfll lfregU;w and I!YagrIaled Acute myeloid leukaemia With reconenr genetic ebroerrautes 113
  • Acute myeloid leukaemIa with t(9;II)(p22;q23); MLLT3·MLL Synonym Ac ute myeloid leukaemia. 11q23 abnor- malities. the prognostic significance of FLT3-JTO mutations in this disease remains unclear /690 , 1199 1. present in 9-12% of paediatric and 2%rJ adult AML 1306 . 7211. Cunicalteatures Patients may present with disseminaled intravascular coagulation. They mayhave extramedullary myeloid (monocytic) serco mas and/or tissue infiltration (gingiva, skn~ Morphology and cylochem;Sby There is a strong association between acute monocytic and myelomooocytlc leukaemias and t(9;11)(p22;q23). altho.ql occasionally the t(9;11) is detected i'l At.( with Of without maturation. MonobIaSlS and promonocytes typically predominale Monoblasts are large cells . with abt.r1ci<rf cytoplasm which can be moderately to.,. tensely basophilic and may shcwtosecco pod lormabon. Scattered fine azurophilo: granules and vacuoles may be preset The rrooobasts usually have round BJCIl'i With del icate lacy chromatin, and one f1 more large prominent nucleoli. Prorcoo cvtes have a more irregular and delicat~ convoluted nuclear configuration; theevtr plasm is usually less basophilic ana sometimes more obviously granulated, with occasional large azurophilic grarUe! and vacuoles. Monoblasts and proro-o cvtes usually show strong positive f'lCJl' specific esterase reactions.The rrcocoass often lack MPO reactivity. Immunophenotype Cases 01AML with the t(9:11)(p22;q23)ir1 child ren are associated with strong exp ression 01 CD33, CD65, CD4 and HLA-DA, while expression at CD13, CD34 and CD 14 is usually low /491 1. Most AML cases with 11q23 abnormalities express the NG2 homologue (encoded by CSPG4j, a chond roitin sulfate molecule reacting with the Mab 7.1124561. MostacU: AMl cases with 11q23 abnormalities express some markers 01 monocac differentiation including CD14, CD4,COlle COl lc. CD64. CD36 and lysozyme, v.tIire variable expression of immature markers such as CD34 and CD1 17 and of CD56 has been reported {154 11. Genetics Molecular studies have identified a t1t.rna'I homologue of the Drosophila trithorax gene designated MLL (HRX), that results in a fusion gene in translocations invo/Vllg 11q231 1141. The MLL protein is a histl)1!! mettwnransterase that assembles in pro. tein complexes that reg ulate gene Iran. 9897/3ICD-O code Definition Acute myeloid leukaemia with t(9; 11) (p22;q23): MLLT3-MLL is usually associ- ated with monocytic features. Variant RARA translocations in acute leukaemia A subset of cases. often with morpho- logical fealures resembling acute ~ cvtc leukaemia. show variant nensocetcos involving RARA. These variant fusion part- ners include ZB TB16 (previously known as promveiocvtrc leukaemia zinc finger gene or PLZF) at l 1q23; the nuclear ma- trix assoc iated gene (NUMA 1) at l 1q 13; the nucleophosmin gene (NPM1)at5q35 and STATSB at 17q l 1.2 124881. Some cases with variant transiocanons were initially reported as having APL morphology 119141. However. the t(l l ;l7) (q23;Q12); ZBTB16-RARA subgroup shc1ws some morphological differences with a predominance of cells with regular nuclei, many granules. usual absence ot Auer rod s. an increased number of Pelgeroid neutrophils and strong MPO activity {19141. The initial cases of APL associated With t(5;17)(q35;q1 2) had a predominant pop- ulation of hypergranular promyeiocvtes and a minor population of hypogranular promyelocytes; Auerrods were not oennteo by ligh t mic roscop y 14761. Some acute promyelocytic leukaemia variants. includ- ing t( 11;17)(q23;q1 2) with ZBTB16-RARA and cases with STAT5B·RARA fusions are resistant to ATAA 114521, APL with the t(5:17)(q35;q 12) appears to respond to ATRA {1452]. Cases with these variant transroc atlons should be diagnosed as AML with a variant RARA translocation. Ep;demk>logy The t(9;11)(p22;q23) may occur at any age. but is morecomnorI in children. being Postulated normal counterpart Myeloid stem ce ll with potential to differ- entiate to granulocytic lineage. Fig.6.08 PM!. anI1bod'y naaM promyeIocybc Ieukaen'Ia showing a etlaractetistic Ill.Ideaf mufbgrnular paltem MIll ru:leoIarexclusion. (oronvelocvnc leukaemia Of PML gene) giving rise to a PML-RARA fusion gene produCII506, 529. 14521. Rare cases 01 APt. lacking the classic t(15:17)(q22;q12) on routine cytoqenenc studies have been described with complex variant transio- cations involving both chromosomes 15 and 17 with an additional chromosome Of with submicroscopic insertion of RARA into PML leading to the expression of the PML-RAR4transcript; these latter cases are considered as cryptic Of masked t(15;17) (Q22;q12) /6471. Morpholog ical analysis shows no major differences between the t( 15;17)(q22;q 12) positive group and the PML-RARA positive patients without t(15;17)(q22;Q12), Secondary cytogenetic abnormalities are noted in - 40% of cases. with +8 being the most frequent (10- 15%). Mutations involving FLT3, including inter- nal tandem duplication (ITO) and tyrosine kinase domain mutations (TKO) occur in 34-45% of APL. FLT3-lTO mutations are most common and are associated with a higher white blood ce ll count. mlcrocran- urar blast ce ll morphology and involve- ment of the bcr3 breakp oint at PML 1318, 747,1 199). Prognosis and pred ictive factors Acute promyetocyttc leukaemi a has a particular sensitivity to treatment with ATRA. which acts as a dilferentiating agent 1342. 2 152/. The prognosis in APt.. treated optimally With ATRA and an anlhracycl ine is more favourable than lor any other AML cytogenetic subtype. and cases of relapsed or refractory APt. show a generally good response with arsenic trioxide therapy 1607.6851. Expression of CD56 is associ- ated witha less faVlJU(able prognosis while 114 Acute myeloid leukaemia and related precursor neoplasms
  • Clinical features Acute myeloid leukaemia with t(6:9) (p23 ;Q34) usually presents with anaemia and thrombocytopenia, and often with pancytopenia, In adults, the presenting white blood cell count is generally lower than other AML types with a median white blood cell count of 12x1()9/L 120351, Morphology and cytochemistry The BM blasts of AML with t(6:9XP23:q34) may have morphologic and cytochemical features of any FAB subtype of AML other than acute promyelocytic leukaemia and acute megakaryoblastic leukaemia. with AML with maturation and acute mvero- monocytic leukaemia the most common 128, 1676,20351_ Auer rods are present in approximately one third of cases, Blasts are myeloperoxidase positive and may be positive or nega tive for non-specific es- terase. Therefore, there are no features specific to the blast cell population in this entity Marrow and PB basophilia. defined as >2%, is generally uncommon in AML but is seen in 44-62%of cases ofAML with t(6;9)(p23:q34). In addition. most cases ""'" evidence oIgarL<ocybc and _ dysplasia. with megakaryocytic dysplasia possibly less common. Ring siderooiaere Definition Acute myeloid leukaemia with the 1(6:9) (p23:q34); DEK-NUP214 is an AML with or without monocytic features that is often associated with basophilia and multilin- eage dysplasia {1714, 20351. abnormalities associated with prior ther- apy or myelodysplasia. such as t(2; 11) (p2 1;q23) or t(11:16)(Q23:p13.3), should be diagnosed as therapy-related AML or AMl with myelodysplasia-related changes (See Chapter on therapy-related myeloid neoplasms), ICD-Ocode The provisional code proposed for the fourth edition of IGO-D is 986513. Acute myeloid leukaemia with t(6;9)(p23;q34); DEK-NUP214 B Fig. 6.09 AML (monoblaslic) WIth t(9;1'Xp22;q23). Bone marrow smears A 5evefall'l'lOl'lllblasts. someWIth very allur'l<Ia1l cytoplasm andh myelopeloxidase,..1iYeazurophilic granules arepresent B Non-speciflc esterllse reacbonshowing I1lensely poslIiYe IrOlOblasts, '" ..Fig. 6.'0 Mt.(1TIOI'I:ltyIic) Mlh 1(9;11)(p22;q23}. BonetJWI(M ~ AThenlarelilMlt8llfOIObIasts and~ with verypalecytor*lsmcontaining numerous fine anrophiic ~_ The promonocyles have delicate rudear lolds. B Noo-speci1ic esteraseSaII"I_ The pn::monocytes are intensely reactive. Epidemiology The t(6:9Xp23;q34)is detected in0.7-1 .8% of AML, and occurs in both children and adults with a median age 01 13 years in childhood and 35 years in adults 1306. 2035,20361. Prognosis and predictive factors Acute myeloid leukaemia with the . 9:11XP22;Q23) has an intermediate sur- .....aIand one that is supefior to AML with e:tner l1Q23 translocations 11531. 18911. Cases with the t(9: 11) and <20% blasts II'IJSt be monitored closely fOf develop- ment of more definite evidence of AML. 'fi1riant MLL translocations in acute leukaemia C>ief 80 different translocalions involving MLL are now described in adult and paediatric acute leukaemia, with over 50 eensiccaton partner genes now cnarac- lenzed11470. 20081. rrensiccetcoe involv- ingMLLT2(AF4). resuitmq predominantly nacute lymphoblastic leukaemia (ALL). end MLLT3(AF9). resuhing predominantly nAML, are the most common. Other MLL eensccauons that commonly result in AML rcuoethe MLLT1(ENL). MLLTIO (AF1O), MLLT4 (AF6) and ELL as partner genes, Other than the MLL-ELL fusion resulting Irom the t(11:19)(q23:p13,1), which is res often associated with only AML, these fusions occ ur predominantly in AML, but may be seen in ALL as well. Up 10 one third of MLL transiocauons in AML eenot detectable on conventional kary- otype analysis , and FISH or other molecular stud ies may be necessary to dentify thesevariant translocations 120081. AML with these fusions usually have myelomonocytic or monoblastic rrorpno- bgic and immunophenotypic features While in the past all of these transloca- li:lns wereencompassed by the category rj AML with 11q23 abnormalities. the di- agnosis should now specify the specific abnormality and should be limited to cases with 11q23 balanced translocations fI'o'OIving MLL. For example. a case of AMl with an MLL-ENL fusion would be dl8gnosed as acute myeloid leukaemia dh ~11 ,19)(q23;p13.3): MLL-ENL. 40Jte myeloid leukaemia with cytogenetic Postulated normal counterpart aaenaiopoeuc stem cell with multiJineage ootennar. scription via ctuomato remodel ing. The ~9:11)(p22:Q23) involving MLLT3 (AF9) is toe most common MLL translocation in AML and appears to represent a distinct enhty. Secondary cytogenetic abnormalities are common with t(9:11) (p22:Q23). with +8 most commonly observed, but do not appear to influence survival [306, 15311. Acute myeloid leukaemia wIth recurrent genetic eoocereetes 115
  • • are present in a subset of cases, The per- centage of 8M blasts is variable. and some cases may present with less than 20% blasts. Immunophenotype The blasts have a non-specific myeloid immunophenolype with consistent ex- pressionofmyeloperoxidase. CD13,CD33. C038 and HLA-DA 128, 1676,20351 . Most cases also express CDl17. CD34 and C015while a subset 01 cases express the monocyte-associated marker CD64 and approximately hall are terminal oeoxv- oodeotidy1 transferase (TefT) positive .Other Iymp/loidantigen expression is Ul'lCOlTITlOl1 . Genetics The 1(6:9)(p23:q34) results in a fusion 01 DEKon chromosome 6 withNUP214 (CAN) on chromosome 9. The resulting nocieo- porin fusion protein acts as an aberrant transcription factor as well as altering nu- clear transport by binding to soluble trans- port factors 119491. The 1(6:9) is the sole clonal karyotypic abnormality in the vast majori ty of cases, but some patients will have the t(6:9)(p23:q34) inassociation with a complex karyotype 120351. FLT3-lTO mutations are very common in AMl with t(6;9)(p23;q34) occurring in 69% of pae- diatric cases and 78% of adult cases 11676. 20351. Fl.T3-TKOmutations appear to be uncommon in this entity. Fig.S." AML. with t(6:9)(p23:Q3-t). The blasts are adn...ed with dyspIastlc erythroid precursors and scallered ~ (centre. '9ll). Postulated normal counterpart Haematopoietic stem cell with mullilineage potential. Prognosis and predictive factors Acute myeloid leukaemia with t(6:9) (p23;q34) in both adults and children has a generally poor prognosis. similar to other AMl with unfavourable cytogenetic ab- normalities. Elevated white blood cell counts are most predictive of shorter overall survival and increased 8M blasts are associated with shorter disease-free survival. Based on limited data. allogeneic stem cell transplantation may be associ- ated with better overall survival compared to patients with no stem cen vansptanta- too 12035I·Cases with t(6;9XP23:Q34) and <20% blasts must be monitored closely for development of more definite evidence of AML. Acute myeloid leukaemia with inv(3)(q21q26.2) or /(3;3)(q2/;q26.2); RPN/·EVIt Definition Acute myeloid leukaemia with inv(3) (021026.2)'" 1(3;3Xo21;q26.2); (RPrvI-EVII) is an AML that may present de novo or arise from a prior MOS. It is often associ- ated with normal or elevated PB platelet counts and has increased atyp ical BM meoakarvcc vtes with mono- or bi-lobated nuclei and associated multilineage dys- plasia (225, 1983,2131). ICO-O code The provisional code propo sed for the fourth edition of ICD-O is 986913. Epidemiology Acute myeloid leukaemia with inv(3) (q21q26.2) ort(3:3)(q21;q26.2) represents 1- 2% of all AML 1306. 20361. It occurs most commonly in adults with no sex predilection. Clinical features Patients most commonly present with anaemia and a normal preteret count . although marked thrombocythaemia occurs in 7-22% of patients 1845.19831. Patients may present de novo or have a prior MOS. A subset of patients present withhepalosptencmegaty.but "",,",,dero- pathy is UllCOI'llllOlI11983. 2C04, 21891. Morphology and cytochemistry Peripheral blood chan ges may include hypogranular neutrophils with a pseudo- Petcer-Hcet anomaly, with or without associated peripheral blasts. Red eel abnormalities are usually mild withOOt teardrop cells. Giant and hypogranulat platelets are common and bare mega- karyocyte nuclei may be present12251.The 8M blastsofAML with inv(3)(q2 1q26.2lcr t(3:3) (q21:q26.2) may have morphologic and cytochemical features of any FAa SUbtypeofAML other than acute promyeIlr cytic leukaemia with acute myebd Ieukaertia withoutmaturation. acute myeIo- monocytic leukaemia and acute mega. karyobIastic leukaemia morphologies rn:lSl cornrnon 1715. 19831. A subset of cases has less than 20% blast cens at the tiTle of diagnosis. including cases withfsallles of chronic myelornonocytic leukaemia Multihneage dysplasia of non-blast eel BM elements is a frequent finding WII/1 atypical megakaryocytes most cQlTllTlCll 1715. 1054. 19831. Megakaryocytes may be normal or increased in number WI many small «30 IJm) monoIobed a bilobed forms. but other dysplastic mega. karsocvtc forms may also occur.Dysplasia of maturing erythroid cells and neutroptws isalso corrrnon. Marroweosooonss.teso phils and/or mast cells may be increased The BM biopsy shows increased sma hyr:x>lobated megakaryocytes. BonemarnJo! cellularity is variable with some casespre- senting as hypocellular AML Marrow fibrosis is variable. Immunophenotype Immunophenotypic studies of AML with inv(3)(q21q26.2) or t(3:3}(q21:q26.2) are limited. The blast cells generally express C013. C033. HLA-OR. CD34 and C03S Blast cells of some cases also aberranf express C07 and a subset may express megakaryocytic markers such as CQ4t and C061. Aberrant expression of lym. photo markers other than C07 appears uncommon [20041. Genetics A variety of abnoemauties of the long arm of chromosome 3 occur in myeloid rnalo(t nances. with inv(3)(q21q26.2) and t(3:31 (q21;q26.2) being the most common.The abnormalities involve the oncogene EVIl at 3q26.2 . or its longer form MOS1-EV! and RPN7 at 3Q21 APN1 may act as<WI enhancer of EVIl expression resulting increased cell proliferation , and impaireo 116 Acute myelOid leukaemia and related orecursoe neoplasms
  • cell differentia.lion: it induces naen etooor- eticcelltransformation (1236, 1609, 21251. Other cytogenetic aberrations involving 3q26.2, such as t(3:21)(q26.2:q22) res- ~tting in an EVI1-RUNX 1 fusion and usu- ally seen in therapy-related disease, are not included in this disease ca tegory. Secondary karyotypic abnormalities are common with inv(3)(q21 q26.2) and t(3;3) (Q21;q26.2) with monosomy 7 most com- mon, occurring in approximately half of cases,followed by 5q deletions and com- "'" ...",.",..11963/. These abroonalrties may precede the development of the 3q262 abnormality 116091. Patents with AMl with inv(3)(q21q26.2) ««3:3Xq2 1;q26.2) show overexpression d EV/1 and GATA2, bulthese fIndings do roappear to be specific for the genetic aonormality 11236,16091. Patients with chronic myelogenous leu- -.aemia may acquire inv(3)(q21q26.2) or (3:3kq21;q26.2), and such a finding usually portends accelerated or blast phase of !heir disease , Cases with both t(9 :22) (Q34;q11.2) and inv(3)(q21q26.2) or t(3;3) (q21;q26.2) are best considered as ag- g-essive phases 01 chronic myelogenous leukaemia. rather than AMl with inv(3) (q2tq26.2) or t(3;3)( q2 1;q26.2). PosllJlated normal counterpart tiaematopoietic stem cell with multilineage POtential. Prognosis and predictive factors AML with inv{3)(q 2 1q26.2) or t(3;3) (q21:q26.2) is an aggressive disease with sort survival 171 5, 1834, 19831. Two pa- tientswith AMl with inv(3)(q2 1q26.2) were reported to show a response to arsenic trioxide with thalidomide, with one act uev- i'19 complete rem ission 11 824 j, Cases lI,ttlinv(3)(q2 1q26,2) or t(3:3)(q 21;q26.2) and <20% bla sts must be monitored ClOSely for development of more definite evidence of AMl. Acute myeloidleukaemia (megakaryoblast/c) with ~1;22)(p I3;q I3); RBMI5-MKL1 Defi1ition ,'cute myeloid leukaemia with t( 1;22) (p13;q13); RBM15-MKL 1 is an AMl gen- EJaJy showing maturation in the mega- karyocyte lineage. ICD-O code The provisional cod e proposed for the fourth edition of ICD-D is 991 1/3, Epidemiology The t(1;22)(p13:q 13) is an uncommon abnormality in AMl, representing < 1% of all cases. It most commonty occurs in infants without Down syndrome, with a female predominance. Clinical features Acute myeloid leukaemia with t( 1;22) (p13;q13) is a de novo AMl restricted to infants and young chi ldren (3 yea rs or less) with most cases occurring in the first 6 months of life (median, 4 months). The 'last rnajonty of cases present with marked organomegaly, especially hepato- splenomegaly. Patients alsohaveanaemia, and usually have thrombocytopenia and a moderately elevated white blood cell count. Morphology and cytochemistry The PB and BM blasts 01AML with t(1;22) (p13;q 13) are similar to those of acute megakaryoblastic leukaemia of AMl, NOS. Small and large megakaryoblasts may be present and they may be admixed with more morphologically undifferent iated blast cells with a high nuclear-cytoplasmic ratio resembling ivmorobrasts. The mega- karvobtasts are usually of medium 10 large size (12- 18 urn) with a round, slightly ir- requrar Of indented nucleus with fine retic- ular ch romatin and one to three nucleoli. The cytoplasm is basophilic , often ag ran- ular, and may show d istinct ble bs or pseudopod formation. Micromegakaryo- cvtes are common, but dyspl astic fea- tures of gra nulocytic and erythroid cells are not usually present The 8 M biopsy is usually normocellular to hypercellular with reticulin and collagenous fibrosis usually presen t. Cases may show a stromal pat- tern of BM infiltration mimicking a meta- static tumour 1205, 341 1. Cytoc hemical stains for Sudan black B (SBB) and MPO are consistently negative in the megakaryo- blasts. A subset of cases will have less then 20% BM blasts. but a low blast cell count due to difficulties aspira ting BM sec- ondary to fibrosis should be excluded . IrrmJnophenotype Themegakaryoblasts express one or more of the platelet glycoproteins: CD41 (glyco- protein lIb/llla), and/or COO1 (glycoprotein ilia). Themore mature platelet-associated Fig. 6.12 AML WIth irlV(J)(Q21q26.2). Bone marrow- aspAte wrlhincreased blasts andatypica, rncnJIobaIed -marker CD42 (glycoprotein Ib) is less fre- quently present. The myeloid~associated markers CD 13 and CD33 may be positive. CD34, the pan-leukocyte marker C045, and HLA-DA are often negative; CD36 is Characteristically positive. Blasts are neg- ative With MPO antibodies. lymphoid markers and terminal deoxynucleotidyl trans ferase (TdT) are not expressed, Cy- toplasmic expression of CD4 1 or COBt is more specific and sensitive than surface staining; the higher specificity is due to possible adherence of platelets to blast cells in other types of AML, which may be misinterpreted as positive staining by flow cvtometrv Genetics Patients should have karyotypic evidence of t(1;22)(p13;q13) or molecul ar genetic evidence of a RBMI5-MKL 1fusion, Inmost cases, t( 1:22)(p 13;q 13) occurs as the sole karyotyp ic abnormality, This translocat ion results in a fusion of RNA-binding motif protem-rs (RBM1S) (also known as OTT) and megakaryoc yte Ieukaemia- t (MKL 1) (also known as MAL) (1352). RBMIS en- codes RNA recognition motifs and aspen paralog and ortholog C-terminal (SPOC) domain, while MKL 1 encodes a DNA- bind ing motif involved in chromatin or- ganization. The fusion gene may modulate chromatin organization . HDX-induced dif- ferentiation and extracellular signaling pathways 11461}. Postu lated normal counterpart Myeloid stem cell with predominant mega- karyocytic differentiation. Prognosis and predictive factors Although early report s suggested a poor prognosis for AM l with t( 1;22)(p13; q 13) 1205.3411. more recent studies have found the patients to respond well to intensive Acute myelotd leukaemia WIthrecurrent genetic abnormalities 117
  • AML chemotherapy with long disease-free survival 16201. Cases with the t(1;22) (p13;Q 13) and <20% blasts on aspirate smears should be correlated withthe biopsy to excjooe 8M fibrosis as a cause of a falsely low blast cell count. 11 this is ex- cluded, these patients must be monitored closely for development of more definite evide nce of AML, such as the presence of extramec ouary disease or myeloid sar- coma, AML with gene mutations In add ition to translocations and inversions, specific gene mutations alsooccur in AML. They include frequent mutations of fms- related tyrosine kinase 3 (FLT3), nucleo- phosmin (NPM 1) and . less corrmonly, mutations of the CEBPA gene (encoding the CCAAT/enhancer binding protein-c). KIT, MLL. WT1, NRAS and KRAS.Alone or in com bination, mutations of FLT3, NPMI and CEBPA have been reported in patients with AML with a normal karyotype where they have prognostic significance in the context of most cu rrent therapies. al- though they may be seen in patients with abnormal karyotypes as well 115321, FLT3, located at 13Q12, encodes a tyro- sine kinase receptor that is involved in haematopoietic stem cell differentiation and proliferation. FLT3 is expressed on these progenitor cells as well as on the blast cells in most cases of AML. FLT3 mutations may occur with any AML type (20-40% of all cases) and in MOS, but are most common in AML with 1(6;9) (p23;q34 ), acute promyelocytic leukaemia and AML with a normal karyotype 11184, 20351, The two primary typ es of FLT3 mu- tations are intern al tandem duplications (FLT3-ITO) within the luxtamembrane do- main (75 - 80%) and mutations affecting codons 835 or 836 01the second tyrosine kinase domain (TKO)(20-35%).'vVhile FLT3 mutations may occur in association with recurrent cytogenetic abnormalities, such as t(6;9XP23 ;Q34)and t(15;17){Q22;Q12), they may also occur with other so-called cooperating mutations. FLT3-HOmulations are associated with an adve rse outcome, but the significance of the less common FLT3-TKO mutations remains controversial 1117, 1447,2396 1. Detection of FLT3-lTO is important because the prognosis of most cytogeneti cally normal AML subtypes correlates with the presence or ab sence of this mutation KIT, located at 4Q11-12, is a member of the type III tyrosine kinase family and encodes a 145-kO transmem- brane glycoprotein. Gain-of-function muta- tions of KIToccur in a variety of diseases, including gastrointestinal stromal tumours. germ cell tumours , mastocytosis and AML Mutations of KI Thave been shown to have prognostic signifICance among AML with t(8;21)(Q22 ;Q22) and inv(16Xp13.1 Q22)1 t(16;16)(p13.1;Q22), in which mey are as- sociated with a poo r prognosis 11696 1. These KITmutations most common ly occur withinexoo 8 and 17.To date, WT1 rrotatcos have been shown to confer a poor prog- nosis in AML patients with a rormat karyo- type 11696AI, but there is less compelling evidence of prognostic significance for the less freq uent mutations of MLL, NRAS and KRAS. Molecular studies have shown tMtthe MLL gene is rearranged more fre- Quently than is revealed by conventional cytogenetic studies. A partial tandem du- plication of MLL has been reported in 5- 10% of ad ults With a normal karyotype [313,6031 and in patients with isolated tri- somy 11[3141. Its adverse prognostic sig- nificance in patients with a normal karyotype is reported to be eliminated in pati ents receiving an auto logous stem ce ll trans- plant in first remission 123951. NPM1 mutations occur in about one third 01 adult AML and CEBPA mutations in 6-15% of all AML. NPM 1mutations are typically heterozygous and the leukaema cells retain a wild-type allele [6671. They usually occur at axon 12 01 the NPMr gene 16661 but rarely involve exon 9 a t1 11n About 40 mutation variants ha...e been described 16671. the most COf1Yl"O'l being mutation A, a TCTG tenanucreotoa dupl ica tion at positions 956 to 959, which accounts lor 70-80% of adult AML wltn NPMI mutation, Independ ent of type, NPM 1mutat ions generate common eje- atrons at the C-terminus of NPM t leukaemic mutants, i.e. replacement o! tryptophan(s) at position 288 and 290Mld creation of a nuclear export signal (NESl motif, which mediates aberrant localiza- tion of NPM to the cytoplasm 16671. CEBPA (CCAAT/enhancer-bind ing pro. teo-c) mutations occur only in AMl <W'C are usually baneic mutations . Thenormal ge ne encodes a transcription factor Ill- volved in control 01proliferation and dd· ferentiation of myeloid proge nitors. Whi'e mutations may occur throughout the whole gene sequence, two general categories of mutation occur: out-of-frame insertions and deletions in the N·terminal regiooart in-frame insertions and deletions in t'le C-terminal region. Mutations of NPM I ere CEBPA are freq uently observed in At.l with a normal karyotype and , in the ab- sence of FLT3-lTO, are associated wma favourable prognosis 1216, 602, 19711 2198 ,23311. In view of the frequency :; Ihese mutations. their prognostic sigM- cance. and their association with certan morphologic and clinical features , it has been suggested that they may ident~' uniqu e subse ts of AML. Therefore, tIW new provisional entities, AML with mutated NPM1and AML with mutated CEBPA are proposed. These have been given provi- sional status because they have beer only recently described and more sfudt is required to confirm these categories as "E re p 118 Acute myeloid leukaerTllaand related precursor neoplasms
  • Tillie &.01 Moleculaf geneticalteratioos allectlrtg dir1ical outcome ofAML patients in specific qtogeoeUc groups. RJJ.m)MII t'1) ...........t,peRTJaWe ""00 .."". w.-P1D """'" ::lflAli mutabCW'lS """'" e_ N,,,,,,, kaizalion01 NPM 'ftIl mutations N''''''' Geoetics KiT mutabon$ <IT_ FiJ><TD IfTlmulations BAAle ""e..., Cytogenatiu Prognosticslgnillcance t(8:21)(q22;q22) OFS andRFS Signlfocann~'~"""'~~-:"'''',,~uenls Wlth KITmutatons (especially ecse ill 8loo17) lXIIf4)8red 'Mtt1 wiId-~ KlTpalients {233A., 2Q09A, CIRandRISlgoificantly higher fofpeteots wilh KITmutaloons compared Wlth patients withwild.fype KIT{310A, 1696} EfS signlf!canny shorter forpabents withKITmutatons (especialy eese ne.oo 17) ~red IIIilh pall8/1ts withw~ KIT(233A. 1969Aj OS si!1liflCalltly shortef I'tlr patents WIth KITmuta!lorls(espec:iaIyIhOs8 ill elOfl17)compared wrltJ pabents wr01 wiId-4ype KlT{233A.. 31QA. 1969A. 2009A} No Slgf1fflcanl dllJerence 111 0$ bereeen patients IIIilh -"' wilhOul KITmutatl(lllS {1696} ilw(16)(p131q22)1 RR'IIIOfSelorpatients wrltJ KlTmutatioos 111 el M 8COIf4lilred WIlt1 patients 'III'l wid-type KrTf33Ml t(16.16)(p13,1;q22) CIRhIglMlI' and OS'/II'OIWfor pabents WIth KIT rrotations 11 elOfll1 c:unpared wr01 PI1ientswithwid-typeKIT{1696} NoSigr*ant dillereooe inEfS , RI, RFS and OSbetween pabentS withand 'Mlhoul KJTrnuIatols (2~ 310A) Normar CRa and DFS~ shor1erfor pabenl$ WIth Fl.T3-lTD comparedwithpalienls 'IIIClOlIl A.TJ.lTD {193A., 216. 736A2394A) EfS SiglWanty sI'o18rlorpatentsWIth fLT3-fTO comperedwotll palienl$ 'IlIltI'loIA A.TJ.lTD (2338) OS~, sIlcrterlorpatlentswotll A.T3-ITO c:unpared withpalients wrlholA FLTJ.lTD {193A. 216. 736Ai No SIgI'ificart dIIetence in OSb8t'ween palietn WI!! a'ld witlCUfLT3-lTD(2338,~ OfS .-.:I OSsqv6c:¥llIy shorterb patients Wlth FlT3-lTO and no8~ rJno-l)1:Ie FlTJaIele ~ 'MiD'! ~ W!IhOut FlTJ.lTD (m4A) OFS sagnficantty shorterforpatienls wit! FLT3-TKD «ll'I'IPB!t:Id Mlh petlenls WIth wild-type FlTJ*'es (23961 CRD (but not OS) SignlfIcal1Uy srorterforpatletlts WIlt1 AILL-PTD compnd withpeli8nlsWIVlout ULL-PTD (313. 603) Noli&renoe inOFS cnl osbetween patlenIswiIhand ntW AoIl-PTD recero'rlg I'IS8nSr¥e treamenllIW*1g a**lgous SCT {2395l CRD and OS~ longer £or patients WIll1 CEBPA mulabalsa:mpared wrlh patients with~ CEBFl4. genes {216, 731} NoSigMIcantdiIIereoce inOSbetweeI'l patienls 'lWilh and withOut CEBFl4. mulalions f233B} EFSsignlflcanUy shorterforpatJeflts with CEBPA rnutaliolls comparedWilli patients 'IIIIhwid-type CEBPA genes f2338} CRrateofpabellts WIth cytopIaSlTic Iocaizaboll ofNPM not 19'1ifical'lUy I)/Ieren! from CRrateofpabenls WJll nudearIocaJiZatiOn of NPM in l,I'Iivariable analysis. Cyloplasri; IocaIzabon 01 NPM wasanintIepen(lenllaYOUr3ble prognosbc IadorforCRachievement in mulbvBl1a!e Iogislic-regres&Oll model inckIding WBC. age,NPM localizatIOn and FLTJ mutations {666} CRrateSigoificantly betterlorpatents wrtI1 NPM1 mulatiOns lhal'llorpalienls W1lh wi:l-type NPMlgeoes {1970} ~ Sigl'lilical'll dillerel1C8 il'lCRrates between patiarllswitharid witt10ut NPMImutations {139A. 233B} DFSaodRFS sigl1lfical'l~y lorIQeffor peeems willi NPM1 mlllabor1$ compared wtlhpatients W1lh wild.fype NPMlgenes {602, 219l1} ~ sigMicaol diflerel1C8 fnRFS between pabenls withandWithoutNPM1 mutatiorls {139A. 2338. 1970} EFSsigniflCilnlty ooget' 101' patients withNPM1 mlltatforls compared withpatients withwild-twa NPMlgenes {1970} ~ Significam dillerel'lC8 inEFSbetween patentswithandwitr.out NPMlmutatiOflS {139A, 233B} Nosignificant dillerence inOSteween patients withandwithout NPMl rl'llItations {139A, 233B. 602, 1970,2198} Normal CRrales, EfS, RFS, DfS andOSsignificantly better lot patientswith NPMfmutations wholackFLT3-ITD compared withpatients wittl NPMlmutations andFLTJ-iTD orthosewith wild·type NPMIgelleS withorwithout FLTJ-ITD NPMlmutations donotseem tosignifi- cantlyalleet poorprognosisofpatientswith FLTJ-ITO {B02, 1970, 2198) Nosignificant dillereoces inEFSand 05 between patents with NPMlmutations andnoFLTJ-ITD compared with patients withNPMf mutations andFLTJ-ITD arid those with wild-type NPMlgenes with orwithout FLTJ-ITD {139A/ Normal Failuretoachieve aCRwith standard induction chemotherapy lorpatients With WTl mutations andFLTJ-ITD {2120Ai, OFS andOSsignificantly shorter forpati$nts withWTl mutallons compared With pabents Wltt'l wiId·type WTI alleles {1696A} i'bmaI CRrateandrate01 primary resistant disease significantly WOfSelor patients withhigh e~pression oflhe BAALC genein blood compared willi patients withloweJqlreSSiOn oftheBAALCgene{1358} Nosignificant diflereooe in CRratesbeWeel'I patieols withhigh aodpaLenls With lowe.pressiOn 01 the BAALCgeoe {l 35A, 216} DFS, EFS. RRand OSsignificat1Uy WOfSeaooCIR significantly htgher for patients With high elpression oflhe BAALCgeoe 11 blood compared 'Mth pabents withIoYt eqJre'SSlon oIth8 BAALCgeoe {1J5A.. 1356,216} Normal CRrates, EFS, CIA, andOSSIgnificantly worse lorPlltJents widllligtl e~ioo oIlhe ERG gene inblood comparedwithpalieols wrlt1 lowe~oflt18 ERG gene{1J9OA, 139OB} Normal OS and RFS significantly shorter and RRhigher forpallenl$ WIth high e~ ofthe MNf genecompared WIth pabents withIoYt elp(8SSion altha ",NI gene (9J7A) lblIiIcI by[) Mnz8k from MrOzek and Bloomtiekl {1531A).-.d MrOzek et Ill, {1532} WIth pemlI$SiDn. EFS ...... SUl'lYII: RFS, ralapse-frM Sl.fVival:OS,ova-aI surYi'IaI;CIA,eurnulative inl:icIence ofrelapse, RI. relapse inQdence: OFS, d1seas&4ree SUI'YMl;RR.fisk of ....FL1J.ITO .,.,. tandem duplalllOllofthe FLngene,FLT.HKD,1IkJtlOOns 11 the tyrOSII18 kinase domiIIo offhll FLDgene,CRO. compIeIe remission dIntioo; AIU.- n ,pnal llwldemduplicabon of118 AIU gene:SCT. stemcellrWlsplanta1ior CR. ~ I'eITissIon; ". NMnal kar)'otype, Acute myeloid leukaemia with reclKrent genetIC abnQIrnaliltes 119
  • • disease. entities rather than prognostic teeters. A small number of AML will show both NPMl and CEBPA mu tations. which would not fit well into the proposed clas- sification structure. In addition, the prog- nostic signi ficance 01 the chromosome aberrations reported to occur in 5-15% of AML with NPM1 or CEBPA mutations is not yet clear. There fore. the presence of any of the recurrent nanstocations or in- versions should be identified in any AML diagnosis. In addition, because of the ad- verse prognostic impact of FLT3mutations in AML with NPMI mutations. mutation analysis 01 FLT3 should always be per- formed with NPM1 and CEBPA These mutations are not de tectable by cytogenetic analysis and are usually detected by PeR. Detection of cytoplasrri: NPM by immunohistochemistry coretaes well with the molecular method [6641.btl similar immunohistochemical surrogate tests are not currently available loraI known mutations. Acute myeloid leukaemia with mutated NPM, Synonym Acute myeloid leukaemia wilh cytooasrc nucreopnosrsn (NPMc+ AML) . 9861/3ICD·Geode Morphology and cytochemistry There is a strong association betweee acute myelomonocytic and acute rrceo- cytic leukaemia and NPMI mutation {666 6671: notably. 80-90% of acute rTIOf()o cvtc leokaerntas show NPMl mctetce, Epidemiology NPM1mutation is one of the most COOlTOl recurring genetic lesions in AML [283, 602.666.667.2198.2331 1. Prevalence increases with age, occurring in 2-8%ci childhood AM L and 27%-35% of adLJII AML. NPMI mutat ions occur in 45- 64%ci adult AML with a normal karyotype 1283 351, 439, 666.2 198, 2331). This disease appears 10 show a female predominance Clinical features Acute myeloid leukaemia with NPMl mutation usually presents without a his- tory of a MDS or MPN {6661. Patients otten exhibit anaemia and thrombocytopenia. but onen have higher white blood cell and platelet counts than other AML types 16021. Patients may show extramedullary involvement. the most frequently affected sites being gingiva, lymph nodes and Skm. Definition Acute myeloid leukaemia with rnnaied NPM 7 carries mutations that usually f'o valve exon 12 of the NPMf gene AbetraW cytoplasmic expression of nucleophosrTrl (NPM) is a surrogate marker of thisgefIe mutation 16661. This AML type IreqJef1l, has myeIomonocytic or rrooocstc feall.Jes and typically presents de novo in ~ adults with a normal karyotype. The WHO Working Group assigned !his lesion 10 a group of provisional ennnee Fig. 6.15 Piedlaf based on 2"6 pabent$ analyZed torItle Ilf99l!I'lC8 01 mutations inItle NPUI andCEBPA genes. FLT3-ITD. FLT3-TKD and AIU.-PTD. E.actI seclof nIc3les the peI'C8flIllge 01 pabenIs harbotmg oneOf ITOOl 0I1he ab'emenliOlllld muIabons. WT rocates pabeftSWlIh only ~ alleles01 genes tes1ed. FromIkozek (If 11I.(1532) lnlltdapled!ram 00IVlllf (If Ill. (602}. Fig. 6.101 Acute myeloid leukaemia with NPAlt mutationsand myelomonocytic features. ABone marrow biopsy showing complete teplacemel'l1 by large blaSCs With abuooanl cytoplasm andIoIded nuclei. B l elillaemic cells are CD34-negalive. C l eukaeJTllC eels show aberrantcyloplasrric expression of rkJdeopilosrr'Wfl (NPM). D EXpt"ession of C231nodeolin isrestricted toItlenucleus. CEB~ +5_ ~ CEBPA+loC.L-PTD+ 1.2% FLJ'3.TKD+/KL·PTD+ 0.8% FlJ'3.TKD+ 2."% R.T3-lTD+/CEBPA+1.6% Fl T3-lTO+IMLl·P"TO+ 2."% FlT3-lTO+ 8.1% NPM'+lFLJ'3.TKD+/ }O " CEBPA+/KL-PTD+ " NPM'+tf:;Un;::;:}o.,,% NPMl+IFLT.J-TKD+/ } , _ CEBAI'+ -" ,. NPAI,+,Fl n.rTO+l} , '" CEllA" NPtrI1+,f=LT.J-m)+/ } , '" FLJ'3.TKD+ - NPM1+.<:ESPJIl,+ 3. ~ 120 Acute myelOid leukaemia and related precursor neoplasms
  • • _ E_ 8ognol (NEll) .-.......-.-- = _..--.s.- lNt-'i ------.--. T._ _ - -...., -c 11 7 89 .)]"12 • • ..-iF.. -..::::::J- I • COOH -, , II I • • • n c '. t • •• ••• t co ' . • , eu 'c . .aoc•••••U '.eOT c••' _•• tc'.' . ............. . .......c .C<.e~ ' . ••. " ." 04" .'.' 04 . • •••04 04 co • • CTe'TT""ee•••' .' u.u••, •• ............., =_ . ...,, NUH D N..., f , 2 3 ..! NPM1 gMfe ~ • • • • N• • • " • • " N ••• " ••• N e WI~ryp. NPM protein Mur.redNPM leul<aemle protein NPOI ' 'u•...,r••" ... . _' '''. . .cc•••••• ~ ' .' . u ••••~. r '. . • .•c••' ' c• •• •• ••• ••••• •• « Fig. 6.16 W*eage IMIlvementin AAlt. WItl'l NPM1 mutabons. A Bone m<mlW biopsy. Massive replac:eITetlt by myeloid blasts wittl maturalJon; !here are also megakaryocyles and occasional irTIrn<I~ erylhnlideels (iIfl'OIW). 8 Thesame case as(A). Myeloid blasts (doublearrtIlltS). rnegakarrocyles andmnaIu'e er)1tWOiCI eels (iIfl'OIW)sI'lOW abemml cytr;lpIasri: po$l~vity lor NPt.I(blue). Immature erythroid eels (arrow)Ill! doubIe--slained lorgIytophonn (brown)andNPM(bkJe~ CBone marrowbiopsy.UinmaIydilIenlnbaled llaIte myeIold leukaemia wrlh NPM1 rllIlaborls, occasionalimmature g~ erythroid cells arepresent 0 Thesame caseas (C). Myeloid bIasls and imrnatIR erythroideels (amlW)showcytoplasmic eKl)feSSion ofNPM. Immunophenotype In addition to myeloid antigen s (CD13, CD33. MPO), the blasts in AML with NPMI mutalion frequently express markers 01 monocytic differentiation , incl uding C014, CD11b and the macrophage- restricted CD68. Theroost striking inYnuno- phenotypic feature 01 AML with NPM 1 mutation, which is independent of the degree of maturation of leukaemic cetls, isthelack of expression of CD34 (666). By immunohistoch emistry on paraffin sections, antibodies aga inst NPM show f e characteristic aberrant expression of the protein in the cytoplasm of leukaem ic cells(6661. In contrast, positivity for C23/ nucleolin (another major nucleolar protein) isrestricted to the nucleus of leukaemic cells. Immunohistochemical detection of caoorasrnic NPM is predictive of NPMI euatoos16641. since the mutations cause critical changes in the structu re of NPM native protein (characteristically located '" the nucleolus), leading to its increased export tram the nucleus and aberrant accumulation in the cytoplasm. However, N.PM1 mutations are also de- tected in AML with and without maturation andin acute erythroid leukaemia. A subset 01 cases shows multilineage dysplasia. These cases usually have a normal ~aryotype and the blast cells are CD34 negative. The 8 M biopsy is usually markedly nvcerceuutar. Bone marrow blast percentages are generally higher in AML with muta ted NPM1 than in other acute myeloid reukaermes with a normal karjOlype 16021. The diagnosis relies on the identification ~ the genetic lesion by molecular tech- !1IQUE!S and/or immunohistochemical detection in paraffin sectoos of aberrant cytoplasmic expression of NPM 16671. mronostaining with anti·NPM antibodies reveals involvement of two or IT'K)(e 8M lineages (myeloid. monocytic. erythroid. megakaryoc ytic ) in the vast majority of ML Wlltl NPMl mutation 116981.The van- ab~lty of 8M cell types showing NPM 1 rrutations accounts for the wide rrorpro- logical spectrum of this leukaemia. , , , Genelies Acute myeloid leukaemia with NPMl ITkrtation is usually associated with a nor- mal karyotype. however. 5- 15% of AML W!ttl NPMt mutation show chromosomal aberrations 1666, 667J, including +8 and de/(9q) 121961.NPMt m..rtabons are usually Fig. 6.17 AclJte myebd leukaerriawithNPM1"'-IlaIions.Mutations usualy0lXIS atexon 12oftlle NPAlI gene.The irs!i:lenlified NPU1rIlIlabons (A" F)Ill! shown (666}.MiDtIonA1$fie most hqI.Jenl acaulbng lcr70-80'10 01cases. AIrn.Jtabllns feSUIt ina:mnon changes atfie e.tllmwu(COOH) 01 fie WlJd.type NPM protein.Thesedlanges (asl!lnst in theNPM nwtated proIeIn) c:onsisl of replacement of~s) aI posibon 288 and 290 andaeation d I ~ exportsqJaI (NES) motil. whiCtllre boIh responsible lor the inc:reased nuclear eJPl and abemIrltt')'lcIpliIsrrC aca.oTUabon of !heNPM 1TlJIlwits. Acute myelOId leukaemia Withrecurrent genetic abnormalities 121
  • Fig.6.18 Prcq10sis ofAML paltents. A,B ThegenotypesNPM'-JFL1J-lTlY'" andCEBA<I'" arelaYCUable progllOSOC markers. C.DUnivariate donor IWSUSno-donof analysis onreepse-rree survival 01AMLwithnormal karyolype infi~ compleIe remission. acttII'ding III g&IlOtype. The donor group ....asdefifled by!heavailability01 a HLA-maIched larrily donor comprising a maId'! in toe loci HlA-A, HLA·B and HLA-DR C Results in AML withli!VOUfab~ genotype NPMf"'lFlTJ-lTO""; (0) !he results inAMl wilt! adverse gerotypes FLT3-/1D"" andNPI,/1"ICEBPA"JFLTJ.lTO""; OnIyAML withactYerse gel'lOtypes (0) benefit from allogeneic stem celIlransptanlalion. From Sd1lenk RF 1:/1aI.{1962AJ 9861/3ICD-Ocode favourable prognosis to AML with a chro- mosomal aberration or with multilineage dysplasia. Morphology and cytochemistry There are no distinctive morpholog ic lea- tures ot AML with normal karyotype an~ CEBPA mutations. but the vast majorityd cases have features of either AML withoJ Of with maturation Less commonl y.cases have monocytic or mveromonocvtc lea- tures. Three percent or more of the blasts are myeloperoxidase or Sudan black B positive, and most cases are non-specific esterase negative. Definition Acute myeloid leukaemia with rnctaiec CEBPA usually meets criteria for AML maturation or AML without maturation,bul some cases may show myelornonocyliC or monobtastic features. This leekaema usually presents de novo. The WHO Working Group assigned ~ lesion 10 a group of provisional entities Epidemiology CEBPA rrc tanons occur in 6-15% 01 de novoAML and in 15-18% of AML W1:tl normal karyotypes 1216, 737, 12801. rtee are no apparent age or sex differences between CEBPA mutated and l"IOI"HTUIale:! AML [20401 Acute myeloid leukaemia with mutated CEBPA Clinical features Acute myeloid leukaemia with metered CEBPA tends to have higher haemogkbn levels. lower platelet counts. lower lactae dehydrogenase levels and higher PB blast cell counts when compared to CEBPA non-mutated AML. This leukaemia type also has a lower frequency of 1ym- phadenopathy and myeloid sarcoma 1216, 7371. Immunophenotype Leukaemic blasts usually express one (J more of the myeloid-associated antigens. CD13. CD33, CD65, C01 1b, and COIS There is usually expression of HLA·[)A and CD34 on the majority of blasts Monoc ytic markers such as C014 anc C064 are usually absent. C07 is preset in 50-73% of cases, while expression It Prognosis and predictive factors Acute mye loid leukaemia with mutated NPM1 typ ically shows a good response to induction therapy 1666) Acute myeloid leukaemiawithmutated NPMI and a normal karyotype, in the absence of a FLT3-ITD mutation. has a characteristicallyfavourable prognosis {283 , 602, 1970, 2198, 2331 1. The coexistenc e of FLT3·ITD mutations is associated with a poorer prognosis. but Ihese patients still appear to have an im- proved prognosis compa red to AML that is NPM1 negative and FLT3-ITD positive 17461. Younger individ uals with AML and a normal karyotype exhibiting the genotype NPM 1mutated!FLT3-lTD negative show a prog nosis that is comparable to that of AML with t(8 ;21)(q22;q22) or inv(16) (p 13.1q22) and may possibly be exempted from allogeneic stem cell transplantation in first complete remission 16021. It is not known whether a NPM1 mutated;flT3-lTD negative genotype also confers a A B - POCO 000 1 - P<o.OO(U l- -1- NPMt-IFl r:J.fI'D-I CESPA- l_.._.. • I: CE8I'A- ~ - NPMr-tFl rJ.,lTO"'" ~_. • .-..-. • • • • • • • • • • • • - • , • • • • • , • • •T_ _ T_ _ C NPM""'/FLT34TD-o 0 _ ", - P-O.71 - P-O.OO3 l- !:- • Donor i-.- - t No-Donor j- Donor - , . • • • • No-Oonor • , • • • • • • • • • • • • • • • • , • • •r_ _ T_ _ Postula ted normal counterpart Haenatopoenc sterncell 113941· mutuallyexclusive of the recurrent genetic abnormalities that define the AML entities described in the preceding section 16651 and with par tial tandem duplicat ions of MLLand CEBPA mutations, although con- currence of these abnormalities with mutated NPMI have been reported 1602, 21981. About 40% of AML with NPM1 mutations also ca rry FLT3-ITD (6661. NPMl mutations appear to precede FLT3- ITO and these Ieukaermas are more genet ically stetne during disease evolution 1439, 21981.AML wilhcytoplasmic mutated NPM1 shows a distinct ge ne expression profile characterized by up-regulation of HOX genes 119. 233 11 that di ffers from that of other AML types. inc lud ing AML with MLL rearrangement 11539). 122 Acute myelotd leukaemIa and related precursor neoplasms
  • CD56 or otner lymphoid antigens is uncommon 1216. 13081. Genetics Seventy percent of AML with CEBPA mutation have a normal karyotype . Fl.T3-lTD mutations occur in 22-33% of cases. Postulated normal counterpart Haematopoietic stem cell. Prognosis Acute myeloid leukaem ia with a normal karyotype and CEBPA mutation is associ- ated with a favourable prognosis. similar to that of AML with inv(16)(p13.1q22) or t(8:21)(q22;q22). The significance of FLT3-lTOon the prognosis of this group (s currently unclear. with small studies sug- gesting either no impact or a negative im- pact on prognosis 1737, 17801. Although uncommon, the prognostic significance of AML with CEBPA mutations and other chromosomalaberrations remainsunclear. Acute myeloid leukaemia With recurrent genetic abncemanoes 123
  • Acute myeloid leukaemia with myelodysplasia-related changes DA ArOOr R D. Brunning A.Orazi BJ. Barn A.P<xw< JW VardllTal MoM. LeBeau P.L Greertlefg Synonym Acute myeloid leukaemia withmultilineage dysplasia. Definition Acute myeloid leukaemia (AML) with myelodysplasia-related changes is an acute leukaemia with 20% or more peri- pheral blood (PB) or bone marrow (8M) blasts with morphological features of myelodysplasia or a prior history 01 a myelodysplastic syndrome (MDS) or myelodysplastic/myeloproliferative neo- plasm (MDSlMPN), or MOS-related cvto- genetic abnormalities, and absence of the specific genetic abnormalities of AMl with recurrent genetic abnormalities. Pa- tients should not have a history of prior cytotoxic or radiation ther apy tor an unre- lated d isease. Therefore, there are three possible reasons for assigning cases to this subtype: AML arising from previous MDS or MOS/MPN ; AML with an MOS- related cytogenetic abnormality; and AMl with multilineage dysplasia. A given case may be assigned to this subtype for one, two oralt three reasons (Table 6.02). ICD-O code 989513 Epidemiology This category of AML with mveiccysptasia- related cha nges occurs mainly in elderly patients and is rare in chi ldren 1913, 12691. Although the definition 01 rnultitin- eage dysplasia is variable in the literature , this category appears to represent 24-35% 01 all cases of AML 169, 869 , 1493, 2465). Clinical leatures Patients with AML with myeiooysprasia- related changes often present with severe pancytopenia. Some cases with 20-29% blasts, especially those arising from MDS or in childhood,may be slowly progressive. These cases, with relatively stable PB co unts for weeks or months, co nsidered refractory anaemia with excess blasts in transformation in the French-American- British Cooperative Group ctassmcauon. may behave clinically in a manner more similar 10 MDS than 10 AMl. _ and cyt""",,",stry Most, but not all cases in this category of AML have morphological evidence 01 muniuneaoe dysplasia which must be assessed on well -stained smears 01PB and BM. To classify an AML as having mve covsoasta-retateo changes based on morphology, dysplasia must be present in at least 50% 01 the ce lls in at least two 8M cell lines. Dysqraouloporesis is character- ized by neutrophils with hypograOlJa' cytoplasm, hyposegmented nuclei (pseLti> Petqer-Huet anomaly) or bizarrely seg- mented nuclei. In some cases, these features may be more readily identiliedoo PB tha n BM smears. ()yseryItlropoiesls IS characterized by megaloblastosis,karp- rhexis and nuclear irregularity, lragTllll1a- hanor multinucleation. Ring sideroblasts, cytoplasmic vacuoles and periodic acid- Schiff (PAS) positivity are addlt~ features of cvsevtnroooesrs. Dysmega- karyopoiesis is characterized by micro- me gakaryocytes and normal sized r:J large megakaryocytes with non-lobulated or multiple nuclei. Dysplastic megakaryo. cvtes may be more readily appreciatedn sections than smears 169, 7421. sorecases wiU not have sufficient rcoees cell 8M elements 10adequately assessb multilineage dysplasia or have sufficietw; non-blast cells but do not meel the crilera described above for a morphologic nosis of AML with multilineage dysplasia These cases are diagnosed as AML mveiodvsptasta-retated changes by ee detection of MD&-related cytogenetic aD- normalities anellor by a prior historyofMDS. -Fig. 6.19 Acute myeloidle~~ withmyelodysptasia-felated changes (murtilillllagedysplasia). The marrow aspirate shows numefOlJS I9"8nulaf blasts as wei as actIuII: hypogrardar neutrophiIs withdul1lled nucleardWomatin and erytt'ftid preanors MttI irreQlAar nuclear am..n. AAsmall. l'lypoIobated rnegakaryotyIe is IQS80I al lhe txb. BAIighermagOOicaIion 01 anoltl8fcase showing rl'ICIre irregIJar nuclearfeatures 01 eryIhroi:I l)"eanors and ~ wiIhcbnped IIUd&ar etwomatn • . 124 Acute myelOtd leukaemia and related precursor neoplasms
  • Immunophenotype Immunophenotyping results are variable dueto the heterogeneity of the underlying genetic changes, In cases with aberralions 01chromosomes5 and 7. a high incidence oICD34, terminal deoxynucleotidyl trans- !erase (TdT), and CD7 expression has been reported 123241. In cases with an- ieceoent MOS. CD34+ cells frequently constitute only a suboopuraton of blasts m mayhavea stem-cell related immuno- pheootype with low expression of CD38 M"dkx HLA-DA. Blasts often express pan- myeloid markers (CD13. CD33). There is 'Tequently aberrant expression 01 CD56 and CD7 116231. The maturing myeloid cells may show patterns of antigen ex- cesson differing from thOSe seen in nQ{- mal myeloid development, and there may ee alterations in the light scatter proper- DeS ofmaturing cells, particularly neutro- tfWs, There is an increased incidence of 'TUlKinJg resistanceglycoprOlein (MOO-1) expressiOn in the blast cells 11206, 1268, 12691. Genetics Chromosome abnormalities are similar to bose found in MDS and often involve gain or loss of major segments 01certain chromosomes with complex karyotypes and -7/del(7q) and -5/del(5q) being most ccmmon 11269, 1530, 1641J, Additional abnormalities that are considered suffi- cient for inclusion in this ca tegory are given in Table 6.03, While trisomy 8 and del(20Q) are also common in MOS, these ffJdingsare not conside red to be disease- specific and are not, by themselves, suf- ficient to conside r a case as AM L with myelodysplasia-related changes, Similarly, bss of the Y ch romosome is a non- specific find ing in older men and should oo! be consi dered sufficient for cyto- [Ie!1etic evidence of this disease category Balarced translocations are less common in tnis disorder, but when they occur are of:en franslocations involving 5q32-33, Tile t(3;5)(q25;q34) is associated with rrOtilineage dysplasia and a younger age alpresentation than most other cases in tisdisease group 1661. In addition, AML W1h inv(3)(q21q26.2), t(3;3)(q21;q26 .2) or W#l t(6;9)(p23:q34) may show evidence of rru/tilineage dysplasia, but these are now :ecognized as distinct entities in the AML 'MIll recurrent genetic abnormalities goup and should be classified as such . '*'wever, cases with the specific 11q23 wrangements. t(11 ;16)(q23;p13,3) and t(2;1 1)(p21;q23), if not associated with prior cytotoxic therapy,should be classified in this group rather than as a variant translocation of 11q23, Cases of AML with multilineage dysplasia may carry NPMI and/or FLT3 muta tions [23561. Most NPMI mutated cases would be expected 10 have a normal karyotype, CD34-negative blasts and no history of prior MDS 120151. However, the presence of an MDS-associated karyotypic abror- mality should take diagnostic precedence over the detection of an NPMI or CEBPA mutation for classification purposes until the significance of such rare genetic c0m- binations is clarified. In patients wIth AML with multilineage dysplasia and a nQ{mal karyotype. information regarding the mu· tational status of NPMI, CEBPAand FLT3 may provide important prognostic infor- mauon.and the presence of these muta- tions should be noted along with the diagnosis of AML with myelodysplasia- related changes (multilineage dysplasia) 123561. Differential diagnosis The principal differential diagnoses are refractory anaemia with excess blasts , acute erythroid leukaemia, acute mega- karyo blaslic leukaemia and the other cat- egories of AML. not otherwise specified (NOS). Caref ul blast cell counts. adner- ence to the diagnostic criteria for morpho- logical dys plasia and evaluation for MDS·related cytogenetic abnormal ities should resolve most cases, with this cate- gory having priority over the purety morpho- log ic categories of AML, NOS, For example, a ca se with >20% 8M myeio- blasts, multilineage dy splasia, over 50% BM erythroid precursors and monosomy 7 should be considered as AML with myelodysplasia-reiated changes rather than acute erythroid leukaemia, Similarly, a case with over 20% 8M megakaryo- blasts and multilineage dysplasia would be considered AML with myelodysplasia- related changes (megakaryoblastic type), Postulated normal counterpart Multipotent haematcooreuc stem cell. Prognosis and predictive factors Acute myeloid leukaemia with myelodys- plastic features generally has a poor prognosis with a lower rate of ach ieving complete remission than other AML types 169. 742 , 1269, 1493, 24651. While there are no overall prognostic differences Table 6.02 Criteria lor the diagnosis of AML with myelodysplasia-relatedfealu!'&S. ~ 20% blood Of mam;lW blasts AND Anyof!tie Ioi:lwing PreW:lus hislDry of myeIodysplaslic syndrome MyeIodysj::QsbC syndrome--relaled L)'IogenetIc abnormalrty (seeTable6.03) Mullilineaga dysplasia AND ......."bdh ?nor cytlItWctherapy loran I.MlIaIed disease RlICllfTing ~ abIllllT1lahl)' asdescnbed inAMl-Mlh reamlOI genetic abroomIakbes. Table 6.03 CytlgenetJc abnorr!alIbes suIIicienI m <iII(p'105e AM.. will myelodyspIasia-leatLRs wnen ~ PB or8M blasts are presett. ('.oorpe. ~' UnbtIIItdd aMoonaiilies ·llde(7ql .-5qJ ~ l1q)'l l1p) ·131de1(13q) del(t1q) del(12pj/l(l2p) "'l9q1 idic(X)(q13) &tI1l11Udabnoonaiities t1:11 ;t6)(q23;p13,3)" t1:311)(q26.2;q22.1)"' t1:1:3)(p36.3:q2t ,1) t{2:11)(p21:q23)"o 1(5;t2)(q33:p12) t(5;1)(q33:qtl .2) t(5;11)(q33;p13) t(5;10){q33;q21) t(3;5){q25:q34) ' >3unrelated abnomlalities, none ofwhich are includedin theAMLwithrecurrent genetic abnor- malitiessubgroup: such casesshould bedassjfied intheaPPfClPriatecytoger.etic group. 0' These abl'lormalities most commonlyoccur in tnerapy-ffllated diseaseand lherapy-relatedAML should beexcluded before u~ng these abnormali- lin asevidence lor adiagnosjs ofAMLwith myeiodysplaSlB-related features. between cases with and without prior MDS 1691. recognition of cases with prior MDS and relatively low blast counts may identify cases with less clinically aggres- sive disease. Some cases with prior MDS and 20-29% 8M blasts, considered refractory anaemia with excess blasts in transformation in the French-American- British Cooperative Group ctess'ucatcn. Acute myeloid leukaemia WIth myelodysplaSIa-related changes 125
  • Fig. 6.20 Survival curve lor casesof acutemyeloidleukaemia withadverse cytogenetic findings inthe "tRC-AMl IO trial Reproduced from Grimwade Det al. {MB}. above, at this time cases of AMl with MOS-related cytogenetic findings and one of these mutations should be diaq- nosed as AMl with myelodysplasia- related changes as well as noting the mutation detected. Diagnostic terminology Because there are different pathways to a diagnosis of AML with myelodysplasia- related changes, which upon further study may have clinical differences, it is recommended that the reason(s) for diagnosing a case as such be included in the diagnosis. For example , a case diag- nosed solel y on morphology would be considered "AMl with myelodyspla sia- related changes (rnultitineage dysplasia)": a case arising from previously diagnosed MOS without associated dysplasia idl!f$- ueo at the lime 01 AMl diagnosis woUd be considered ~AMl with myelodysplasaa- related changes (following prevos MOSt; and a case with prior MOS. dys- plastic features and monosomy 7 WCllil be considered "AMl withrnyeIoctyspIase related Changes (fotleJ'oNing previous MDS-associated cytogenetic a~ and muttilineage dysplasia). Cases NPM1, CEPBA and/or FLT3 mutatll)'lS should also indicate the mutation hndrYJ (r.e. "AMl with mverocvsotasta-reraiec changes (multilineage dysplasia) aM NPM1 mutation"). Finally, because ollhe possible cli nical heterogeneity of cases with low blast cell counts (20-29%), tt:E blast count should be clearly stated int~ report. v.... ,,""' ....... , --t_ 4... • I !, •• may behave in a manner rrore similar to MOO thanomeAML. These cases . as well as cases with myelodysplasia and just under 20% blasts, require regular moni- toring of PB counts and 8M morpholOgy lor changes suggesting disease progres- sion to overt AML. Although AMl with multilineage dysplasia is generally associated with a poor prog· nests. several studies have not found morphology to be a significant parameter when using multi-variant analysis thaI also incorporates the results of cytogenetic analysis, high risk cytogenetic abnormal- ities being more significantly associated with prognosis {869, 2356, 24651. There- fore, mUltilineage dy splasia should be considered as a possible indicator of high risk cytogenetic abnormalities, but in the absence of such abnormalities. may not be important. In such cases, fluorescence in situ hybridization (FISH) studies for MO$-related abnormalities may be useful. It is currently unclear whether a NPM1 posl livefFLT3-negative genotype in AMl with multilineage dysplasia confers the same good prognosis as in other AMl with NPM, mutations. Cases of AML with multilineage dysplasia and NPM1 meta- none usually do not have adverse cyto- genetic findings or a history of prior MOS 120151. However. the clinical impact of mutation status versus the presence of multumeaqe dysplasia requires more investigation. Therefore, it is not yet clear how cases of AML with multilineage dys- plasia without prior MOS or MOS·related cytogenetic abno rmalities and with an NPM1 mutation or a CEBPA mutation should be classified. However, as noted 126 Acute myeloid leukaemia and related precursor neoplasms
  • I"" Therapy -related myeloid neoplasms JW. Vardiman DA Arber RD. Bruming RA Larson E. Malutes I. Baumann J Thiele Definition Inis category includes therapy -related acutemyeloid leukaemia (I·AML). rnyelo- dysplastic syndrome (I-MDS) and myelo- dysplastic/myeloproliferative neoplasms (t-MDS/MPN) occurring as late compliea- 'ons 01 cytotoxic chemotherapy and/or -adtatlOn therapy administered lor a prior '«lPIastic or non-neoplastic disorder. AI- h:lu'Jh some patients may be diagnosed nnpt'dogicatty as 1-"'-105, t-MDS/MPN ()( ~AML according to the number 01blasts present. all of these therap y-related neo- plasms are bes t considered together as a IIlJque clinical syndrome. Excluded from mig categor y is tran sformation of MPN srce it is etten not possible to determine if !his is disease evolution or therapy- related. 992013 &,nlnym Therapy-related acute myeloid ielJ:.aemia. NOS. -k>Iogy Therapy-related t-AMl.../t-MDS and t-AMLJ l.MDS!MPN account for 10- 20% of all cases of AML, MDS and MDS/M PN 11278, 1433, 15361. The incidence among pa- ieras treated with cytotoxic agents varies ElCcording to the underlying disease and fe treatment strategy. Any age group rraybe affected but the risk associated lIllh alkylating agent or rad iation therapy jjerlefally increases with age whereas the rsillor those treated with topoisornerase II II'hbIlors is similar across all ages 1651, 12781, E"*'lJy Therapy-related neoplasms are thought to betheconsequence of mutational eve nts mceoby cytotoxic therapy, Some indi- OOualsmayhave a heritable predis position due topolymorphisms in genes that affect drug metabolism or DNA -repair rnecha- ~sms. but for most cases the underlying 08thOgenesis remains uncertain 118991. Cy1oIoxic agents commonly implicated ire istec in the Table 6.04. Although other the rapies such as hydroxycarbamide (hydroxyurea), radioisotopes, L-aeoaraq- inase and naematcootetrc growth teeters have been suggested to be reukaemo- genic, their primary role in therapy-related haema tologic neoplasms. if any. is not clear. Characteristic clinical, morphologic and genetic features often relate to the previous therapy received . Sites of involvement Peripheral blood (PB) and bone ma rrow (BM) are the principle sites of involvement. Clinical features Nearly an equal number of patient s give a history of treatment for a previous baema- tologi cal ma lignancy as for a non -haema- tolog ical solid tumour. However. 5- 20% of patients are reported to have received cy- totoxic therapy lor a rco-oecoasrc disease. A smlar number develop a therapy-related myeloid neoplasm after high dose chemotherapy and autologous haemato- porenc stem cell transplant for a previ. ously treated malignancy 11433. 20411. Two subsets of t-AMlIt-MDS and t-AMU t-MDS/MPN are generally recognized , The most common occurs 5- 10 years afte r exposure to alkylating agents and/or ionizing radiation. Patients often present with t-MDS and evidence of 8M failure with one or mul tiple cytopenias, although a minority will present with t·MDS/MPN or with overt t-AML This cate gory is com- monly associated with unbalanced loss of genetic material. often involving chromo- somes 5 and/or 7. The second category of t-A ML/t-MDS and t-AML/t-MDSIMPN encompasses 20-30% of patients. has a latency period of about 1- 5 years, and follows neannent with agents thai interact With DNA tcoosorerase II (topoisornerase II inhibitors). Most patient s in this subset do not have a mveioovsotasnc phase but present initially with overt acute leukaem ia tha t is often associated with a bal anced cororoscrat translocation1651, 1716,20411, Although it may be useful to consider t-AMlIt-MDS and t-AMU t-MDSIMPN as being alkylating agent and/or radiation- related or astop:lisctnerase IIirtlibitor-related. Fig. 6.21 Therapy.retaled AML witht(9;11)(p22;q23). This pabenldeYeloped 1-AMl. 1essltlanoneyearfoIow. inginstilulion oIlherapy lorosteosartoma. Thetherapy included both alkylabl'lQ agentS and ~ II in- hibilorn. in practice many patients have received polychemotherapy that includes both classes of drugs and the boundary be- tween the two categories is not always sharp 120411. t.1o<pIloIogy The majority of patients present WIth t-AMlIt-MDS associated with multllineage dysplasia. Commonly, but not invariably in such cases, a history of prior therapy with alkylating agents and/or rad iation therapy is elicited and cytogenetic stud- ies reveal abnormalities of chromosomes 5 and/or 7, or a complex karyotype, Nev- ertheless, dysplasia may be seen in some cases with balanced transiocauons as well. The P8 shows one or more cvto- pemas . Anaemia is almost always present and red cell morphology is cha racterized in most cases by macrocytosis and poik- ik::x:ytosis,Dysplastic changes in the neutn> phils include abnormal nuclear lobation, particularly hypolobatoo, and cytoplasmic hypogranulation. Basophilia is frequently present 114721. The 8M may be hyper. ce llular, normcceuurar or twpoc euuiar. and slight to marked 8M fibrosis occurs in approximately 15% of cases. Dysgranu- lcpoiesis and dyserythropoiesis are pres- ent in most patients, Ring sideroblasts are reported in up to 60% of cases and in some cases exceed 15% of the erythroid precu rsors. Megakaryocytes ....ary in nurn- Therapy-related myeloid neoplasms 127
  • 00 000 °00 O· __ 000 0 0°0°° 00.p~ .• _ o 0000°000 &0 , _ 000 00 0 0 00 . 10.Q 0 0000 00 0 00 ~ 00 0 0 0 00 °00 00 0 1 A O OO. O O O_O..~O!?C . , • Fig.6.22 Thefapy-relaled MDSlAML This 42-year-old man was lrealed withABVD therapy lordassical HodglinIymJ:tloma but retapsed 161T1OflthS laterandwas!Jven 9vage chemolt1erapy and radiolt1erapy, Two years laterhe presented W11t1 pancytopenia in l!lePB(A),a BM asprate (8) and BMtMopsy (C) st'lowtld ilCteased bass and mullili1eaile dysplaSia.Acomplex karyotype Jnduded lossofd1romosomes 5 and7. Ionizingradiationtherapy large fields IfIcIuding active bone marrow Topoi_ aMIl inhibiton EIOpOSide.1eoipO!iiOe. dolOfban, d8ulorIbcin.lIWJ.dnlrorle, arnsacrnt. acIIrom';an "TCJP(lI5OlTIeIaS IIirlhbIr:Jts may abo be associated WIltIIherapy-related ~ leukaemia ....kylating agents Melphalan. cydophosphamide, nitrogenmustard, cI*lrafnbldl. MuIIM,carboplalin. eisplabn , dacarbazirle, procarbazine.carmustine. mitomycin C .lh~epa,lomus ~ne. etc. to their de novo counterparts 1681.Blasts are generally CD34+ and express pan- myeloid markers (CD 13, CD33), There 1$ frequent aberrant expression of CD56 andlor the lymphoid-associated marker CD7. The maturing myeloid cells may show patterns of antigen expression that differ from that seen in normal myeloid development. and there may be alterations in the light scalier properties of maturing cells. particularly reutropnus. Genetics The leukaemic cells of over 90% eX patients with t-AMUt-MDS show an abn ormal karyotype, The cytogenetic abn ormalities often correlate with the laten t period between the initial lherapy and the onset 01the leukaemic disorder and With the previous cytotoxic therapy 11254.1433,1716, 1886,20411. Approx- imately 70% of patients harbour urea- anced chromosomal aberrations. mainly whole or oaruat loss of chromosomes 5 and/or 7, that are often associated wit!l one or more additional ch romosomal abnormalities [e.g. del(13q ), del(2OQl, del( 11q ), del(3p), -17, -18, -21, +8} in a complex karyotype. These changes are usually associated with a long latent pe- riod . a preceding myelodysplashc phase or t-AMl with dysplastic features, and alkylating agent and/or radiation therapy The remaining 20-30% of patients have balanced chromosomal translocaticns that involve rearrangements of 11Q23 [including us,11)(p22:q23l and t( 11 :19) (q23;p13l]. 21q22 [inc luding t(8;2t) (q22;q22) and 1(3;21)(q26.2:q22.1)] and other abnormalities such as 1(15;17) (q22;q12) and inv (16)(p 13q22) , The bal- anced transtocanons are generally asso- ciated with a short latency period, most often present as ove rt AMl without a preced ing mverocvsptasnc phase. and associated with these chromosomal abnormalities 136. 1886 . 2034 1although a lew cases may present as MDS or have dysplastic teatures as well . Many cases fall in the categories of acute monoblaslic leukaemia or mverononocvtcleukaemia. but cases with granuloc ytic differentiation also occur Case s morphologi ca lly (and cytogenetica lly) identical to those ob- served in all of the subtypes of AMl With rec urring cytogenetic abnormalities have been described , inc luding acute pronverocvnc leukaemia , Such cases should be designated as t-AMl with the appropriate cytogenetic abnormality indi- cated. e.q. t-AML with t(9; 11)(p21;q23 ). Cases of lymphoblastic leukaemia (All ) also occur in this group, usually associated with a t(4 ;t 1)(q2 1;q23) chromosomal abnormality 11022,19841. Immuoophenotype There are no specific immunophenotypic findings in t·AMUMDS ()( in t-AMljt-MDS/ MPN. lmmunophenotyping studies reflect the heterogeneity of the und erlying mor- pholog y and often show changes similar """"Anilmetaboilles:thiopurines, ITl)'tOI)Ilenolate,fludarabine AntitublJlin agents(usuallyincomblnenco withother agents):vincristine, vinblastine, virdesine, paditaxet, docetaxel ber but dysplastic forms of variable size with rnooo- orhypolobated or widely sep- arated nuclei are seen in the ma;orlty of cases 11472, 164 71- The percenteae 01 blasts also varies but in patients present- ing with a rnyelodysplastic pha se almost 50% will have less than 5% 8 M blasts 11472, 2026J About 5% of pat ients have features of MDS/MPN, such as chronic mveromooocvnc leukaemia 120261. Al- thou gh patients presentmq With rnyeio- dysplasia and cvtoperaas may be designated as l-Moo ort-AMl depending on their morphology and blast counts. such subclassification may lack clinical significa nce 120261. In 20-30% of cases, the first manifestation of therapy-related myeloid neoplasm is overt acute leukaemia without a preced- ing myelodysplastic phase, Often , but not invariably, these cases follow toposo- merase II inhibitor tnerapy. The majority of the cases are associated with balanced recurrent c hromosomal transtocanons that frequently involve 11q23 (MLL) or 21q22 (RUNX1) , and have morphology that resembles de novo ac ute leukaemia 128 Acute myeloid leukaerrua and related precursor neoplasms
  • areassociated with prior toootsomerase IIinhibitor therapy. Postulated normal counterpart Haematopoietic stem cell. Prognosis and predictive factors The prognosis 01t-AML./l-MOS and t-AMU -MDS/MPN is generally poor. although it is strongly influenced by the associated karyotypic abnormality as well as the comorbidityof the underlying malignancy or disease for which cytotoxic therapy wasl'itialyrequired. CNeratl, 5-year SlJVivaI of less than 10% is commonly reported . Cases associated with abnormalities of chromo some 5 and/or 7 and a com ple x karyotype have a particularly poo r out- come. with a median survival time ot less than one year regardless 01whether they present as overt acute leukaemia or as t-MOS11472, 20261. In contrast to de novo MOS, some reports have suggested that neither the blast percentage nor subclas- sification have a significant impact on clinical outcome, and the designation of t-AMUt-MOS or t-AMUt-MDS/MPN may be more appropriate 11472. 20261.Patients with balanced translocations generally have a better prognosis, but. except for those with t(15;17)(q22;q 12) and inv(16) (p 13.1q22) or t(16;16)(p 13.1;q22). me- dian survival times are shorter than for their de novocounterparts 136. 227 , 1886. 2034.20411 . It should be noted that occ asional pa- tients assigned to the category of therapy- related myeloid neoplasms represent coincidental disease and would be ex- pected to behave like other de novo disease. Therapy-related myeloid neoplasms 129
  • Acute myeloid leukaemia, not otherwise specified D.A. Arber R D. Brunning A.Orazi A. Porwil L. Peterson J. Thiele M.M. Le Beau Acute myeloId leukaemia with minimal differentiation Epidemiology These cases comprise <5% of cases of AML. The disease may occur at any age, but most patients are either intants or older adults. Morphology and cytochemistry The blasts are usually of medium size with dispersed nuclear chromatin, round or slightly indented nuclei with one or two nucleoli. The cytoplasm is agranular with ~ ..f ig. 6.23 AcuIe myeloblastiC leukaemia. minirnaI"· enlJated. A&nI 1I8TOW sme¥. The blasts wary IISilt. ilITICV1t d ~ and prorrWlen(;e d ru:id. ThM ate no QfferenlIabng lealU'8$. B Bone man'OW sedioIl TIislxlne marrow isCOl,lpIetely replaced bytusts..,. Olf 11l1lerenbalJng I8alures. a varying degree of basophilia Less fre- quently, the blasts are small with more condensed chromatin, inconspicuous nucleoli and scanty cytoplasm resem- bling lymphoblasts. The cytochemical reactions for myeloperoxidase (MPO), Sudan Black B (SBB) and naphthol-ASD- ctnoroacetete esterase (CAE) are neqe- tive «3% positive blasts): a naphthyl acetate and butyrate esterases are nega- tive or may sbow a noo-specmc weak C1 local reaction distinct from that 01 rT"IOOl> cvtrc cells 1186, 1084, 18801. In some unusual cases of AML with minimal ditter· ennanon there may be a residual norma population of maturing neutroonue. These cases may resemb le AML with mature- non.but are distinguished by the absence of MPO or SBB positivity in the blasts and the abse nce of Auer rods, The BM sec- tions are usually markedly hvoerceuuie with poorly differentiated blasts. With sen- sitive ultrastructural studies, MPO, CAE ac tivity may be demonstrated in sma 9872/3ICD-O code Definition Acute myeloid leukaemia with minimal differentiatioo is an AML with no evidence 01 myeloid differentiation by morphology and light mic roscopy cytochemistry. The myeloid nature 01 the blasts is demon- strated by immunological markers and/Of ultrastructural studies including ultra- structural cytochemistry. Immunopheno- typing studies are essential in all cases to distingui sh this disease from acute lym- phoblastic leukaemia (ALL) , Clinical features Patients wiltl AML, minimally differentiated usually present with evidence of BM failure With anaemia, ltl rombocytopenia and neu- tropenia. There may be leukocytosis with a markedly increased number of blasts, PB smears, and 8 M trephine biopsies, The recommendations for classification are applicable only to specimens obtained prior to chemotherapy. It should be noted that most of the epidemiologic data cited for each AMl, NOS entity has been largely gathered from studies using the prior FAB classi fication scheme, and may not directly apply to series of patients classi fied by the WHO system, in which most patients will be classified into other, more specific entities, and fOf which suf- ficient epidemiologic data is not yet avail- able. The category of acute myeloid leukaemia, not otherwise spec ified (AML. NOS) en- compasses those cas es that do not fulfil criteria lor inclusion in one of the previ- ously desc ribed groups with recurrent genetic abnormalities, myelodysplasia-re- lated changes or thai are therapy-related . These tumours are fell 10be derived from haematopoietic stem cells. The clinical relevance of some subgroups 01 AML. NOS is of questionable significance 169. 21531 but they are retained in the classifi- cation because they define criteria for the diagnosis 01AML ac ross a diverse mor- phologic spectrum and include the unique d iagnostic criteria for ervmroreukaemra. Mutation analysis and cytogenetic stud- ies are recommended for cases in this category and may offer more prognostic significance than the morphologic sub- types. The pr imary basis for subclassi- fication within this category is the morphological and cylochemical/immuno- phenotypic features of the leukaemic cells that indicale !he major lineages involved and the degree of maturation. The defin- ing cntenon for AML is 20% or more mveioorasts in the peripheral blood (PBl or bone marrow (BM): the promonocytes in AML wiltl monocytic differentiation are considered blast equivalents, The classi- fication of acute erythroid leukaemia is uniqu e and is based on the percent age of abnormal erythroblasts for pure ery- throid leukaemia and the percentage of myeloblasts among non-erythroid cells for the erythroid/myeloid type. It is recom- mended that the blast percentage in the BM be determined from a 500 cell differentia! count using an acceptable Romanowsky stain. In the PB, tne differ- ential should include 200 leukocytes: If Ihere is a marked leukopeni a, bufty coa t smears can be used , Should an aspirate smear not be obtainable due to BM fibrosis and if the blasts express CD34, immuno- histochemical detection of CD34 on biopsy sections may provide valuable informa- tion and may allow the diagn osis of AML if the 20% blast threshold is mel. The major criteria required for this category are based on examination of BM aspirates, 130 Acute myelold leukaemia and related precursor neoplasms
  • • Fill.6.2" Acute myeloid leukaemiawithout maturation. Bone marrow smear. AThecellsarepredominanlty myelobIasts: OCC3S;onal myeloblasts containazllrophilic grarlules orAller rods. There is rIO e'o'iOenc41 01 maturationbeyornllhe myeloblast stage. B Myeloperoxidase reaction showing OOmertlUSmyeIoblasls with strong peroxidase reactivity.There areseYeraI peroxidase negative tfYlhroid precursors ifl the centre. the blasts is demonstrated by MPO or S8B (3% or more of blasts) positivity and/or Auer rods. Clinical features The patients usually present with evi- dence of 8M failurewithanaemia, thrombo- cytopenia and neutropenia, There may be a leukocytosis with markedly increased blasts. 9874/3ICO-D cod e Acute myeloid leukaemia with maturation Definition Acute myeloid leukaemia with maturation is characterized by the presence of ~ blasts in the BM or PB and evidence of maturation (~10% matUringcells of neutro- phil lineage); cells of monocyte lineage com prise <20% of BM cells. Genetics There is no demonstrated association be- tween AML without maturation and spe- cific recurrentchromosomal abnormalities. The immunoglObulin heavy chain gene and T-eel! receptor chain genes. in most cases, are in a germline configuration. C064. C011b is expressed in a fraction of cases. Blasts are negative for B- and T- associated cytoplasmic lymphoid mark- ers: cC03. cC079a and cCD22 . CD7 is foond in -30% of cases, while expression of other membrane , lymphoid-associated markers such as C02, C0 4, CD19 and C056 has been described in 10- 20% of cases Differential diagnosis The differential diagnosis includes ALL in cases with blast cells lacking granules or having a low percentage at MPO-positive blasts, and AML with maturation in cases with a higher percentage of MPD-positive blasts. ~~iilblbm' Acute myeloid leukaemia with maturation comprises approximately 10% of cases 01 AML (691. It occurs in all age groups; 9873/3ICD-O oode Morphology and cytochemistry Some cases of AML without maturation are characterized by obvcos mveicorasts. some of which have azurophilic granulation and/or unequivocal Auer rods. In other cases, the blasts resemble Iymphoblasts and lack azurophilic granules: MPO and SBB positi vity are present in a variable number of blasts, but always in at least 3%. The 8M biopsy sections are usually markedly nvperceuutar although rormo- cellular ornvooceuuiar cases may occur. Epidemiology Acute myeloid leukaemia without matura- tion comprises 5- 10% of cases of AML. It may occu r at any age but the majority of patients are adults; the median age is ap- proximately 46 years. Immunophenotype Acute myeloid leukaemia without matura- tion usually presents with a popu lation of blasts expressing MPO and one Of more of myeloid-associated antigens such as C0 13, C033 and C0117. C034 and HLA- OR are positive in approximately 70% of cases. r,~q'6' ,~ ~%'l '~~' ,';7 ex~<%'SiJ'l'i' of markers associated with granulocytic maturation such as C0 15 and C065 or rrcnocync markers such as C014 and Genetics Nounique chromosomal abnormality has been identi fied in AML with minimal dif- ferentiation. The most common abnor- malities previously reported are complex karyotypes and unbalanced abnormali- ties, such as -5/del(Sq), -7/del(7q), +8 and del( 11ql, but the presence of some 01 these abnormalities would now place the case in the category of AML with myelodysplasia-related changes. Muta- tions of RUNX 7 (AML 7) occur in 27% of cases and 16-22% of cases have FLT3 mutations. Definition Acute myeloid leukaemia without matura- tion is characterized by a high percent- age o! 8M b la.''-.ts »l~I,~1 $~":li~ic.5'71· evidence of maturation to more mature neutrophils. Blasts constitute ~% of the roo-erythroid cells. The myeloid nature of Acute myeloid leukaemia without maturation granules. endoplasmic reticulum, Goigi areaand/or nuclear membranes. Differential diagnosis The differential diagnosis includes ALL, acute megakaryoblas!ic leukaemia, mixed phenotype acute leukaemi a and more rarely. the leukaemic phase of large cell lymphoma. Immunophenotyping studies are essential to distinguish these condi- oons 1",,,,,,,OP"011Otype Most casesexpressearty, heernetoooetc- associated antigens (such as CD34, CD38 and HLA-DR) and lack antigens associated with myeloid and monocytic maturation. such as CD11b. C01S , CD14, CD64 and CD65 Biasi cells usually ex- press CD13 and/or COl 17 while expres- sion of CD33 is found in approximately 60% of cases, Blasts are negative tor B- and T-associated cytoplasmic lymphoid markers cCD3, cCD79a and cCD22 . MPO is negative by cytochemistry. but may be positive in a fraction 01 blasts by flow cytometry Of immunohistochemistry. Nuclear terminal oeoxvnocieonoyttrans- terase (TdT) is positive in approximately 50% of cases. Expression of CO? has been reported in approximately 40% of cases, while expression of other mem- bfane,lympood-associated markers israre. Acute myeloid leukaemia. not otherwise specified 131
  • Genetics There is nodemonstrated association be- tween AML with maturation and specific recurrent chromosomal abnormalities. expression of HLA-OR, CD34 and/or CDl 17, which may be present only in a fraction of blasts. Monocytic markers such as CD14 and CD64 are usually ab- sent. CD7 is present in 20-30% of cases. while expression of CD56, C02, CD19 and CD4 is uncommon (- 10% of cases) . Differential diagnosis The differential diagnosis includes retrac- tOf'y anaemia with excess blasts in cases with a low blast percentage, AMLwithOut maturation when the percentage of blasts is high, and acute myelomonocytiC leukaemia in cases with increased mono- cvtes. Epidemiology Acute myelomonocytic leukaemia c0m- prises 5-10%of cases of AML. uocccan all age groups but ismore corrrnoo inddEJ individuals; the median age is 50 years, There is a maleJemaIe ratio of 1.4:1 120781. Clinical features Patients typically present with anaerre and thrombocytopenia, fever and fatigue The white blood cell count may be high with numerous blasts and promonocytes Morphology and cytoct>erT;sOy The monoblasts are large cells, wm abundant cytoplasm which can be m0d- erately to intensely basophilic and may show pseudopod formation. Scaneeo fine ezurconmc granules and vacuoles may be present. The monoblasts usuaJy have round nuclei with delicate lacycee- mann and one or more large prominert nucleoli. Promonocytes have a more ir- regular and delicately convoluted nucIe<r con figura tion: the cytoplasm is usua~ less basophilic and sometimes more oIr viously granulated, with occasional large azurophilic granules and vacuoles. Mono- cvtes and promooocvtes may not always be readi ly distinguishable in routinely stained BM smears. The PB typically shows an increase in monocytes. whlch are often more mature than those in the BM. The monocytic component may be more evident in the PB than in the 8M,N. least 3% of the blasts should show MPO positivity. The monoblasts, promonocytes, and monocytes are typically non-soecnc esterase (NSE) positive, although in some cases reactivity may be weak or absent. II the cells meet morphologic criteria IO' monocytes. absence of NSEdoes notex- clude the diag nosis. Double staining IO' NSE and CAE or MPO may show dual positive cells , 9867/3 Acute myelomonocytic leukaemia Definition Acute myelomonocytic leukaemia is an acute leukaemia characterized by the proliferation of both neutrophil and mono- cyte precu rsors, The PB or BM has ~20% blasts (including prorronocvtes): neutro- phils and their precursors and monocytes and their precursors each comprise at least 20% of BM cells, This arbitrary min- imal limit of 20% monocyt es and their precursors disting uishes acute myelo- monoc ytic leukaemia from cases of AML with or without maturation in which some monocyte s may be present. A high num- ber (usually ~5x 1 09/L) of monocytic cells may be present in the PB, ICD-O code Oinical features Patients often present with symp toms r elated to anaemia, thrombocytopenia and neutropenia. The white blood cell count is variable as is the number of blasts. _ogy and cytochemisOy Blasts with and without azurophilic granu· larion are present. Auer rods are frequently present. Promyelocytes, mveiocvtes and mature neutrophils comprise at least 10% of the BM cells; variable degrees of dys- plasia are frequently present. Eosinophil precursors are frequ ently increased but do not exhibit the cytological or cyto- chemical abnormalities characteristic of the eosinophils in acute myelomonocytic leukaemia. associated with inv(16)(p13,l q22). Basophils and/or mast cells are some- times increased. The BM biopsy is usually hyoerceuular. F"1g.6.25 N»ts l'I'Iylllod leulo:BMilI Wllh mlll.ralD'" Booe marrow &ITlNf. kl~ tJ !he myeIobIa$l$. lhere 8111 sewraI more malure nevtrophIs; one neutrophI has a psetJdoPelger-HIJill Ikldeus. 20% of patients are <25 years of age and 40% are ~ years of age 120781. Immunophenotype l eukaemic blasts in AML with maturation usually express one or more of the myeloid-associated antigens, C0 13,C033, C065, C0 11b and C01 S. There is often 132 Acute myeloid IeukaEtnlla and related precursor neoplasms
  • --~7"f'll.6..27 Acute myeIomonocytIe 1eI*aen'ia. ABIoocI smear. myeloblast monoblast al'ld prormnocytes. B Bone marrow smeaf. MyelobIas1s.1ld smnIlOOre mallJ'e mooocyte5 rdudir9 prornonocytes, CNm-specific esterase reactionon• bone marrow smear. 5eYetaI NSE positi'Ie eels819 presert. The l'ICIl'Hll8dII1 eels 8111 ~ myeIcitlIasls m~ preaJ ~. n;.6.21 A Acute monoblaslic leukaemia, Bone marrow biopsy showingcomplete replacement by a ~lation of llrge blastswilh abundantcytoplasm. The nuclei aregeneraly rOI.Ild to oval: occasional nuclei are di&lol1ed 8 Acute <TIO'lOCytiC leukaemia Bone marrow sedion. The nudea!'IoIds inthepromonocyles arepfOmineol. Acutemonoblastic and monocytic leukaemia findings and percent of monocyt ic cells. The differential diagn osis with chronic myelomonocytic leukaemia is critical and relies on the proper identification of promonocytes. Morphology and cytochemistry Monoblasts are large cells , with abundant cytop lasm which can be moderately 10 intensely basophilic and may show pseudopod formation. Scattered fine azurophilic g ranules and vacuoles may be present. The monoblasts usually have round nuclei with delicate lacy chromatin, and one or more large prominent nucle- oli, Promonocytes have a more irregular and delicately con voluted nuclear config- uration; the cytoplasm is usually less ba- sophilic and sometimes more obviously granulated , with occasional large azure- philic granules and vacuoles. Auer rods are rare in acute monoblastic leukaemia and. when present, are usually in ce lls ident ifiable as myeloblasts. Haemophago- cytosis (eryttrophagocytosis) may be 0b- served and suggests an associated t(8;16)(p11 .2:P13.3) chromosomal abnor- mality 120791. Haemophagocytosis wilh an associated t(8:16)(pll.2:p 13.3) may also be observed in AML with maturation. The monobtasts and prornonocytes usu- ally show intense non-specific esterase activity in most cases, In up to 10-20%of cases of acute monooasnc leukaemia, the Clinical features Bleed ing disorders are common present- ing features. Extramedullary masses . cutaneous and gingival inlit1ration. and central nervous system (eNS) involve- ment are common. Epidem iology Acut e monoblastic leukaemia com prises <5% of cases of AML. 11 may occur at any age but is most co mmon in young indi- viduals, Extrameduliary lesions may occur. Acute monoc ytic leukaemia comprises <5% of cases 01AML: the mare.ternare ratio is 1.8:1. It is more common in adults (median. 49 years) 120781. 9891/3ICD-O cod e Definition Acute monoblastic leukaemia and acute monocytic leukaemia are myeloid leukaemias in which 80% or rrcre of the leukaemic cells are of monocytic lineage including monoblasts, prorooocvtes and monocytes : a minor neutrophil component, <20%, may be present. Acute monobIastic leukaemia and acute monocytic leukaemia are distingu ished by the relative proportions of monoblasts and promonoc ytes. In acute monobreettc leukaemia, the majority of the monocytic cells are monob lasts (typ ica lly ~80 % ) , In acute monocytic leukaem ia, the majority of the monocyti c cells are crornonocvtes. Differential diagn osis The major differential d iagnoses include AML with matu ration, acute monocytic leukaemia and chronic mvelomonocync leukaemia. The distinction from the other MiL types is based on the cytochemical Genetics Myeloid-associated, non-s oecrnc cyto- genetic abnormalities, e.g. +8, are pres- ent in the majority of the cases. !rrmunophenotype These ieusaemras generally show several populations of blasts variably expressing myeloid antigens C013. CD33, COO5 and CD15, One of the blast populations is usually also positive for some markers characteristic of monocytic differentiation such as CD14, CD4, C0 11b, COl le, CD54.CD36,macrophage-restricted CD68 (PGM1), CD l63 and lysozyme. In partic- ular. co-expression of CD15 and strong C064 is characteristic of monocytiC dil- ferentiatoo. There is often also a popcta- m olirrmature blasts thai express CD34 <rdIor COll]. Mostcases are positive for ~-DR. approximately 30% for CD7, illtlile expression 01 other fvmpnoc-asso- Ciated markers is rare. Acute myeloid leukaemia, not otherwise spec ified 133
  • can be distinguished with well-stained smears. The differential diagnosis with chronic myetomonccytc leukaemiaiscrit- ical and relies on the proper identification of promonocytes and their inclusion as blast equivalents. The abnormal promyeb- cvtes in APL are intensely MPOand CAE positive whereas the monocytes are weakly reactive or negative. Fig. 6.30 Acute erythrcleukaemia. erythroid/myeloid. BOlle marrow smear. A Myeloblasls anderythroid precursors with dyserythropoietic changes arepresent. B Bone marrowsmear Perocc acid-Schiff reaction. There arese~eraI erythroid precursors atvaryingstagesof maturation wilh PAS-positi~ cytoplasm. The more immatureprecursors Mile acoarsely granularil10bularreaction; thelaterstage precursors haveadiffuse cytoplasmicpositi~Fty. Fig. 6.29 Acute monocytic leukaemia, testcclar infiltralion Al ow magnification of a biopsyot a testisfrom a patienl with acute monocytic leukaemia. There is extensiveexpansion andinfiltrationof tile space between the seminiferous tubules. 8 ThemonocyIic cellsnave relati ~e ly abundant cytoplasm and ~ery dispersed chromatin. • 9840/3 .'• Acute erythroid leukaemia ICD-O code Definition Acute erythroid leukaemias are acute leukaemias that are charac terized by a predominant erythroid popu lation. Twa subtypes are recognized based on the presence or absence of a significant myeloid (granulocytic) component: Erytnroleukaernia (erythroid/myeloid) is def ined by the presence in the 8M of ~50% erythroid precursors in the entire nucleated cel l popula tion and <::20% myeloblasts in the non-erythroid cell pop- ulation, i.e. the myeloblasts are calculated as a percent of the non-erythroid cells. Pure erythroid leukaemia represents a neoplastic proliferation of immature cells (undifferentiated or proerythroblastic in appearance) committed exclusivelytothe erythroid lineage (2:80% of BM cells) with no evidence 01 a significant myeloblastic componen t 1753). Epidemiology Erytnroleukaernia (erythroid/mye loid) is predominantly a disease of adults (20781. It compr ises <5% of cases of AML. Pure erythroid leukaemia is extremely rareand can occ urat any age, including childhood Genetics Myeloid-associated, non-specif ic cytoge - netic abnormalities are present in the ma- jorityof the cases. The t(8;16)(p11.2;p13.3) may be associated with acute monocytic leukaemia or acute myelomonocytic leukaemia and, in the majority of cases, is associated with haemophagocytosis by leukaemic cells, particularly erythrophago- cytosis and coagulopathy 12079). Differential diagnosis The major differential diagnosis of acute moncorastrc leukaemia includes AML without maturation, AML minimally differ- entiated and acute megakaryoblastic leukaemia.Extramedullary myeloid (mona- blastic) sarcomas may be confused with malignant lymphoma or soft tissue sarco- mas. Occasional cases resemble prolvm- phocytic leukaemia; they are readily distinguished by immunophenotypic analy- sisand cytoch emistry. The major differen- tial diagnosis of acute monocytic leukaemia includes chronic mvelomono- cytic leukaemia, acute myelomonocytic leukaemia and microgranu lar acute promyelocytic leukaemia (APL). These non-specific esterase reaction is negative or very weakly positive. In some of these, immunophenotyping may be necessary to estab lish monocytic differentiation, Monoblasts are typically MPO negative; promonocvtes may show some scattered MPO positivity. The BM biopsy in acute monobtastrc leukaemia is usually hyper- cellular with a predominant population of large, poorly differentiated blasts with abundant cytop lasm, Nucleoli may be prominent. The prornonccytes in acute monocytic leukaemia show nuclear lobu- lation. The extramedul lary lesion may be predominantly of monoblasts or prornono- cvtes or an admixture of two cell types. Immunophenotype By flow cytometry these leukaemias vari- ably express myeloid antigens C013, C033 (often very bright), C015 and C065. There is generally expression of at least two markers characteristic of mono- cytic differentiation such as C014, C04, C011 b, C011c, C064, C068, C036 and lysozyme, C034 is positive only in 30% of cases, while C0117 is more often ex- pressed, Almost all cases are positive for HLA-OR. MPO may be exp ressed in acute monocytic leukaemia and less often in monoblastic leukaemia. Aberrant ex- pression 01 C07 and/or C056 is found in 25-40% of cases.Byimmunohistochemistry in paraffin-embedded 8M biopsy speci- mens and in extramed ullary myeloid (monobtast'c) sarcomas , MPO, CAE are typica lly negative but may be weakly pos- itive. Lysozyme is often positive, but is rel- atively non-specific. Macrophage-specific CD68 and C0163areoftenpositiveand ap- pearto be morespecific formonocyticdiffer- entiation. 134 Acute myeloid leukaemia and related precursor neoplasms
  • Fig.6.33 Pure erythroid leukaemia,Bone marrow section, A Apredominant population of veryimmature erythroid pre- cursors, some ofwhich aremuRilobated (arrow). B The immature erythroid precursors andmrtoticfigures showposi- tivityfofglycophorin A. Immunophenotype Erythroleukaemia (erythroid/myeloid) The erythroblasts in ervtbroieokaemia generally lack myeloid-assoc iated mark- ers and are negative with anti-MPO; they react with antibodies to haemoglobin A and glycophorin, but the more immature cells may be negative. An aberrantly low expression of CD71 may be present. The immunophenotype of the myeloid popu- lation usually corresponds to that 01 AML without differentiation or AML with minimal differentiation. Pure erythroid leukaemia The more differentiated forms can be de- tected by the expression of glycophorin and haemoglobin A and absence of MPQ and other myeloid markers; the blasts are often negative for HLA-DR and CD34, but may be positive for CD117. The more im- mature forms are usually negative for gly- cophor in or this is only weakly expressed in a minority of blasts. Other markers such as carbonic anhydrase 1, Gero antibody against the Gerbich blood group or CD36 are usually positive as they detect erythroid progeni tors at earlier stages of differentiation. However, CD36 is not spe- cific for ervtbrobrasts and may be (proerythroblast): the cytoplasm is deeply basophilic, often agranular and frequently contains poorly demarcated vac uoles which are often PAS-positive, Occasion- ally the blasts are smaller and resemble the Iymphoblasts of ALL. The cells are negative for MPO and SBB; they show re- activity with a -naphthyl acetate esterase, acid phosphatase and PAS, the latter usu- ally in a block-like staining pattern, In the BM biopsies of pure acute erythroid leukaemia the cells appea r undifferenti- ated. -Fig.6.32 Pureerythroid leukaemia. Bonemarrow smear with numeroos very immafure erythroid precursors;these cells have cytoplasmic vacuoles which occasionally coalesce, Fig.6.34 Pure erythroid leukaemia. A Bone marrow smear shows fourabnormal ptcerythrcblasts. The erythroblasts arelarge withfinely dispersed chromatin.prominent nucleoliand cytoplasmic vacuoles, some ofwhfch are coalescent. B The cytoplasm of the proerythroblastsshows intenseglobular PAS staining. Pure erythroid leukaemia The undifferentiated form of pure ery- throid leukaemia is usually characterized by the presence 01 medium to large size erythroblasts usua lly with round nuclei, fine chromatin and one or more nucleoli " ,..... Fig. 6.31 Acute erythroid leukaemia, erythroid/myeloid. Bone marrow biopsy, There is a population of erythrokl precursors and myeloblasts refiectingtheduallineage proliferation. Abinucleate megakaryocyte is present. Morphology and cytochemistry Erythroleukaemia (erythroid/myeloid) All maturation stages of the erythroid pre- cursors may be present, frequently with a shift to immaturity. The erythroid precur- sors are dysplastic with meparobras torc nuclei and/or bi- or multinucleated forms; the cytoplasm in the more immature cells frequently contains poo rly demarcated vacuoles, which may coa lesce , Large multinucleated erythroid cells may be present. The rnveioorasta are of med ium size, often containing a few cytoplasmic granules and occasionally Auer rods and aresimilar to the mveiobrasts in AML with and without maturation.Dysplastic changes of maturing neutrophils and megakaryo- cytes are common, The iron stain may show ring sideroblasts and the perio dic acid-8chiff (PAS) stain may be positive in reerythroid precursors either in a globu- lar or diffuse pattern. The MPO, CAE and SBS stains may be positive in the myelo- blasts. The 8M biopsy in erythroid! myeloid leukaemia is usually hypercellu- ar. There may be prominent mega karyo- cytic dysplasia. Clinical features The clinica l features of the eryth roid leukaemias are not unique but profound anaemia and circulating erythrob lasts are common, Erythroreukaernia (erythroid! myeloid) may present de novo or evolve from MDS or, less commonly, from chronic myeloproliferative neop lasms (MPN), Acute myeloid leukaemia, not otherwise specified 135
  • Acute megakaryoblastic leukaemia erythroid precursors, a diagnosis can be established , howeve r some cases are ambiguous and there may be cases with concurrent erythroid-megakaryocytic in- volvement. Epidemiology Acute megakaryoblastic leukaemia oc- curs in both adults and children. This is an uncommon disease comprising <5% of cases of AML . quent. An association between acute meqekarvonrasnc leukaemia and media- stinal germ cell tumours has been oc- served in young adult males 115941. Morphology end cytochemistry The megakaryoblasts are usually of medium to large size (12-18 jJm) with a round , slightly irregular or indented l'MJ- cieus with fine reticular chromatin andce to three nucleoli. The cytoplasm is base- prune.often agranular, and may showdis- tinct blebs or pseudopod formation. In some cases the blasts are predominaf1ty small with a high nuclear-cytoplasmic rato resembling Iymphoblasts; largeand small blasts may be present in the sere patient. Occasionally, the blasts occur I'l small clusters. Circulating micromega- karyocytes. megakaryoblastic fragments, dysplastic large platelets and hypogral- urar neutrophils may be present. Micro- megakaryocytes are small cells with 1rx 2 round nuclei with condensed chromalfl and mature cytoplasm: these should rwx be counted as blasts. In some patients, because of extensive 8 M fibrosis restJ!.- ing in a "dry tap ", the percent of 8M blasts is estimated from the 8M biopsy. Imprints of the biopsy may also be uselul. Although acute megakaryoblastic leukae- mia may be associated with extensive fibrosis, this is not an invariant finding. The histopathology of the biopsy vanes from cases with a uniform population of poorly differentiated blasts to a mixtureof poorly differentiated blasts and maturing dysplastic megakaryocytes; varying de- grees of reticulin fibrosis may be present. Cytoc hemical stains for SBB, CAE and MPQ are co nsistently negative in the megakaryob lasts ; the blasts may show reac tivity with PAS and for acid phos- phatase and punctate or focal non- specific esterase reactivity. 99 10/3ICD-O code Definition Acute megakaryoblastic leukaemia is an acute leukaemia with 20% ()(more blasts of which at least 50% are of megakaryo- cyte lineage; however, this category excludes cases of AML with myelodys- plasia-related changes, AML with t(1;22)(p13;q 13), inv(3)(q21q26.2), t(3;3) (q21 ;q26.2) and Down syndrome-related cases. Prognosis and predictive factors Erythroid/myeloid leukaemia is generally associated with an aggressive clinical course. The morphologic findings may evolve to a more predominant myeloblast picture. Pure erythroid leukaemia is usually associated with a rap id clinical course. Clinical features Patients present with cytopenias. often thrombocytopenia, although some may have thrombocytosis. Dysplastic features in the neutrophils, erythroid precursors, platelets and mega karyocytes may be present. Hep atosplenomegaly is intre- Genetics There is no specific chromosome abnor- mality described in this type of AML. Complex karyotypes with multiple struc- tural abnormalities are common, with -5/del(Sq), -7/del(7q) and +8 the most corrvnon 112821. However, cases with -5/del(Sq), -7/del(7q) and/()( complex chromosomal aonomaunes should be classified as AML with myelodysplasia- related changes if the other requirements f()( that category are satisfied. expressed mo-ocvtesand megakaryo- cvtes. Antigens associated with mega- karyocytes (CD41 and CD61) are typically negative, but may be partially expressed in some cases. Immunohistoc hemistry to haemoglobin A or glycophorin may be helpful in establishing cell origin in biopsy specimens. Differential diagnosis ~(~)shouId be distinguished from refractory anaemia with excess blasts (RAEB) , AML with myelodysplasia-related changes, AML with maturation with increased erythroid precu rsors and reactive erythroid hyper- plasia following therapy sx administration of erythropoietin. A BM differential count of all nucleated cells should be per- formed. If the overall percentage of blast cells is ~20% and muJlilineage dysplasia is present in ~50% of the cells of two or more lineages, a diagnosis of AMl with myelodysplas ia-related changes should be made . When there are <20% total blasts and the erythroid prec ursors are ~50% of all cells, the differential count of non-erythroid ce lls should be ca lculated. If blasts are ~20% of non-eryth roid ce lls, the diagn osis is erythroleukaemia (ery- throid/myeloid); if <20%, the diagnosis is usually MOS. The differential diagnosis of pure erythroid leukaemia includes megalo- blastic anaemia due to vitamin B 12 or folate de ficiency. In equivocal cases, a trial of 81 2 or folate thera py should be considered. Pure erythroid leukaemia without morpho- logic evidence of erythroid maturation may be difficult to distinguish from other types of AML . particularly megakaryo- blastic leukaemia, and also from ALL or lymphoma lack of expression of lym- phoid antigens will exclude the latter diag- noses. Distinction from megakaryoblastic leukaemia is the most difficult: If the immunophenotype is characteristic of 136 Acute myeloid leukaemia and related precursor neoplasms
  • r _ B fig.6.36 ACVle mega~ 1eI.*aenia. A Bone marrow smear. The two megaka-yoblasts are large ceHs with GytlpIasmic pseudopod lonnatiOn: portIOnS of the cytqllasm are"zoned" withgranular basoplliliC areas anddear ~_ Nucleoli cwelAl$lJ3ly ptCIII1nerL B Bone marrow smear reac:t8d wrth alllilOOy toCD61(pIal9lel: gIycopro- .., II).TheeyklpIasm ofthe ITlI!9lkalyoblasls isin&enSeIy reactJYe •:.til Fill, 6,37 Acu1e megakaryoblastic 1eJkaen'ia. Bone Il'¥I'OW biopsy shows vi1uaRy ~ repIacemenl by apopuIaIion 0/blasts CI'ld weW1IerenhaIed megakaryo. cya There isan'WlOl" popJabon 0/8I)'IIVOidpreanors, Epidemiology This is a very rare disease with a relatively small number of reported cases, com- prising < 1% 01 all cases of AML. Acute basophilic leukaemia Definition Acute basophilic leukaemia is an AML in which the primary differentiation is to ba- sopnns. Clinical fea tures As in other acute reokaemras. patients present with featu res related to 8M failure and mayor may not have circulating blasts, In addition, cutaneous involve- ment, organomegaly, lytic les ions and symptoms related to hyperhistam inemia may be present. Morphology and cytochemistry The circulating PB and 8 M blasts are of medium size with a high nuclear-eytoplasmic ratio, an oval, round or bilobed nucleus characterize d by dispersed chromatin and one to three prom inent nucleoli. The cytoplasm is moderately basophilic and contains a variable numbe r of coarse ba- sophilic granules wh ich are positive in metachromatic stains; vacuolation of the cytoplasm may be present. Mature base- phi ls are usually sparse. Dysplastic tea- lures in the erythroid precursors may be present. Electron microscopy shows that the granules contain structures charac- teristic of basophil precursors; they contain an electron-dense particulate substance, are internally-bisected, e.g. have a theta character, or contain crystalline material arranged in a pattern of scrolls or lamel- lae , the latter finding is more typical of 987013ICD-O code Prognosis and predictive fact ors The prognosis 01 this category 01 acute mecakarvobtasnc leukaemia is usually poor when compared to other AML types as well as in comparison to AML with t( 1;22XP13;q 13) 1620, 16371 and acute megakaryoblastic leukaemia in Down syndrome, but these cases are all assigned to other categories of AML (See AML with recurrent genetic abnormalities), In young males with mediastinal germ cell tumours and acute meqakarvobtasuc leukaemia. several cytogenetic acoomau- ties have been observed of which i(12p) is characteristic. Differential diagnosis The differential diagnosis includes mini- mally differentiated AML, AML with myelodyspl asia-rela ted changes, acute panmyelosis with myelofibrosis, ALL, pure erythroid leukaemia and blastic transfor- mation of chronic myelogenous leukaemia or rneqakarvobrasnc crisis of any MPN. In the latter two conditions, there is usually a history of a chronic phase and spleno- megaly is an almost constant finding. Some metastatic tumours in the 8M, par- ticularly in c hildren , e.q alveo lar rhabdo- my osarcoma , may resem ble acute meqakaryobla stic leukaemia. In general. acute meqakarvoblastic leukaemia repre- se nts a prol iferation pr ed omi nantly of rneqakarycbtasts. whe reas acut e p an- myelosis is characterized b y a trilineage proliferation, i.e. granulocytes, megakaryo- cvtes and erythroid precursors. The dis- tinction between acute megakaryoblastic leukaemia, acute pan myelosis with fibrosis and AML with myelodysplasia-related Changes is not always clear. Genetics There is no unique chromosomal aonor- Te'rty associated with acute meqakarvo- blastic leukaemia in adults . Complex r.aryofypes typical of MDS, inv(3) !:321(126.2) and t(3;3Xq21q26.2) can all be associated with megakaryoblasticl n!gak.aryOcytic differentiation 1507, 16371 0rm.n0phen0Iype The meqakarvobtests express one or '!'(Jfa of the platelet glycoproteins: CD41 19yooprotein 1Ib/llla). and/Of COOl (gly- coprotein ilia). The more mature platelet- associated marker CD42 (glycoprotein Ib) s less frequently present The myeloid- associated markers, CD13 and CD33. 'fay be positive. C034. lhe pan-Ieukocyte marker CD45. and HLA-OR areoften neg- alIVe. especially in children; CD36 is char- acteristically positive. Blasts are negative with !heanti-MPO antibody and with other markers 01 granulocytic differentiation. Lymphoid markers and TdT are not expressed. but there may be aberrant eqxesson of CD? Cytoplasmic expres- sion of CD41 or C06 1 is more specific and sensitive than surface staining, due tl possibleadherence of platelets to blast ,:ells, which may be m isinte rp reted as positive staining by flow cytometry In cases with fibrosis, immuno phenotyping 011 BM trephine biopsies is particularly mportant for di agnosis. Meg akaryocytes and in some cases rreqakarvobrasts can te recognized by a positive reac tion with antibodies to von wmeorand's factor, the platelet glycoproteins (CD61, CD 42b) irld LAT (linker of activation of r-cenej the eetecton of platelet glycoproteins is the rest lineage specific but detection is Ilighly dependent on procedures used for ixationand decalcification. Acute myeloid !eukaerma, not orrerwse specified 137 1
  • mast cells. ,Coexistence of basophil and mast cell granules may be identified in the same immature cells {17321. The most charac teristic cytochemical reaction is metachromatic positivity with toluidine blue. In addition. the blasts usually show a diffuse pattern of staining with acid phosphatase and . in some cases. PAS· positivity in blocks or lakes; the blasts are often negative by light microscopy for SBB, MPO. CAE and non-specmc es- terase. The BM trephine biopsy shows dif- fuse replacement by blast cells. F"Ii-6.38 Acute~ 1eINema. Bone marrow smear. A Blasts and irrmature basophiIs. The bascJpIj pUIs varyfrom large roarsegraUesIIIsmaI8rpUBs. B Bonemarrowtrepl1n8 biopsy.The bIa:sls /we pco1y~ Synonyms Acute (malignant) myelofibrosis, acute (malignant) myelosclerosis. Epidem iology Acute panmyelosrs with myelofibrosis is a very rare form of AML APMF occurs de novo. It is primarily a disease of adults but has also been reported in children. Prognosis and predictive factors Since this is a rare type of acute leu- kaemia. there is little information on sur- vival. The cases observed have generally been associated with a poor prognosis. _logy and cylochem;stty The PB shows pancytopenia whic h IS usually marked. The red blood cells show no or minimal anisopoiknocv tosrs and variable macrocytosis; rare erythrob- lasts can be seen but teardrop-shaped cells (dacryocytes) are not observed. Occasional neutrophil precusors inc::kJl:ilv blasts may be identified. Dvsotastc Changes in myeloid cells are frequent Abnormal platelets may be noted. aoe marrow aspiration is frequently uosoc- ce ssful: either no 8M is obtained or ee specimen is suboptimal. Bone marroe biopsy supplemented with immunohis:o. logy is required for diagnosis /2124. 2225 1. The 8M biopsy is hypercelljjw and shows , within a diffusely fibrotIC stroma. an increased pronteratco of ery- throid precu rsors. granulocyte precursors and megakaryocytes (panmyelosis).wt'ich is variable in terms of the relative prooc- tion of each given component. Charac- teristic findings include foci of immature baematcpolettc cells including blasts associated with conspicuously dvsplastc megakaryocytes predominately of smat size with eosinophilic cytoplasm showing variable degrees of cytological atypiail'l- eluding the presence of hypolobulatedcr non-lobulated nuclei with dispersed crso matin. Mic romegakaryoc ytes may be present but should not be counted as blasts. The visibility of the small meqa- karyocytes may be accentuated with the PAS stain and immunohistochemistry l22251. The overall frequency of blastsir APMF marrows is uncertain. Based onBIll biopsy, a median value of 22.5% was found in a recent study /16511. Mosl cases have a range of 20-25%. The degreed myelofibrosis is variable. In most patients there is a marked increase in reticulir fibres with coarse fibres; frank collageroo; fibrosis is. however, uncommon. Immunophenotype If sufficient 8M specimen is obtained!o' immunologic markers or circulating bIas:s are present in the P8. the cells sh:)w phenotypic heterogeneity, with va~ degrees of expression of myeloid-aSSOCI- ated antigens. The blasts usually express 9931/3ICD-O code Acute panmyelosis with myelofibrosis Definition Acute panmyelosis with myelofibrosis (APMF) is an acute panmyeloid prolifera- tion with inc reased blasts and accompa- nying fibrosis of the 8M {168, 21201that does not meet criteria for AML with myelodysplasia-related changes. Clinical features Patients present acutely with severe con- stitutional symptoms including weakness and fatigue; fever and bone pain are also frequently observed. Pancytopenia is always present. There is no or minimal splenomegaly. The clinical evolution is usually rapidly progressive 122251. 'rrm.Jnophenolype Leukaemic blasts express myeloid mark- ers such as C013 arldJor C033, and are usually positive for CD 123. C0 203c and CD 11b. but negative for other monocytic markers. Blasts may express CD34 and in contrast to normal basophils may be positive lor HLA-DR but are negative for CD 117. Immunophenotypic detection of abnormal mast cells expressing CD1 17. mast cell tryptase and C0 25 will distinguish mast cell leukaemia tram acute basophilic leukaemia. Usually blasts show expres- sion of COO. Some cases may be positive for membrane CD22 and/or TdT. Other membrane and cytoplasmic. Iymphoid- assoc iated markers are usually negative 11295.20741. Genetics There is no consistent chromosomal abnormality identified in these cases. AML with t(6:9)(p23;q34) is specifically excluded as are cases associated with a BCR-ABL 1fusion gene. Differential diagnosis The differential diagnosis inc ludes blast phase of MPN, other AML subtypes with basophilia suc h as AML with t(6;9) (p23:q34), mast cell leukaemia and , more rarely, a subtype of ALL with prominent coarse granules. The clinical features and cytogenetic pattern will distinguish cases presenting de novo from those resulting 'rom transformation of chronic myeloge- nous leukaemia and from other AML sub- types With basophilia. Immunological markers will distinguish between granu- lated AlL and acute basophilic leukaemia and light microscopic cytochemistry lor myelope roxidase and elect ron ml- croscopy will distinguish acute basophilic leukaemia from other leukaemias. 138 Acute myeloid leukaemia and related precursor neoplasms
  • the progenilotlearly precursor-associated market CD34 and one or more myeloid- associated antigens: C013, C033 and CD117 11651, 2124, 22251. Myeloperoxi- dase is usually negative in the blasts. In some cases a proportion of immature cells express erythroid antigens. Immuno- histochemistry can facilitate the identi fi- cation of the relative proportions of the various myeloid components on the biopsy specimen and is generally used to confirm the multilineage nature of the proeteranon. This is usually done by employing a panel of antibodies which in- clodes myeloperoxidase, lysozyme, anti- megakaryocytic markers (C061. C0 42b , C041 or anti-von Wil1ebrand 's factor) and erytIYOid markers such as gtycophofin and haemoglobin A. These confirm the pres- eoce 01 parvnyelosis and allow exclusion ci specific ·unilineage" -predominant pro- ilerations.such as acute rnegakaryObtastic ~emia . GeneIics If sufficient specimen for cytogenetic analysis is obtained, me results are usu- ally abnormal. The detection of a com plex karyotype, frequently Involving chromo- somes 5 and/or 7 [-51del(5q), -7/del{7q)] 122251, means that the case is assigned to AML with myelodysplasia-related changes, not to acute panmyelosis. Differential diagnosis The major differential diagnosis of APMF includes other types of AML with associ- ated BM fibrosis including acute mega- karyoblastic leukaemia 116511. Usually ess problematic is the distinction from primary myelofibrosis (PMF), post-poly- cythaemia vera myelofibrosis, post-essen- ~al lhrombocythaemia myelofibrosis, and eon other neopla sms that can be en- countered in a myelofibrotic BM such as metastatic malignancies with a de srno- plastlcstromal reaction. The distinction be- tween AML. particularly cases of AML with myekxiysplasia-related changes with multi- ~neage dysplasia and myelofibrosis and acute megakaryoblastic leukaemia with myelofibrosis, and APMF may be difficult, particularly if no specimen suitable for cyto- genetic analysis can be obtained. If the proliferative process is predominantly one cell type. i.e. myeloblasts, and there is associated myelofibrosis, the case should be classified as AML with a specific sub- type, e.g. AML-myelodysplasia-related. and then designated with the qualifying phrase ·w ith mveronbrosrs". Acute mega- karyoblastic leukaemia is associated with the presence of 2':20% blasts, of which at least 50% are megakaryoblasts. In con- trast, the blasts of APMF are more het- erogenous, poorlydifferentiated and express CD34. The majority of blasts do not display megakaryocytic reactivity,and the prolifer- ative process involves all of the major BM cell lines. Particularly difficu lt is the distinction be- tween APMF and cases of MOS associated with both an excess of blasts and myelofi- brosis (AAEB-F), since the latter cases can share roost of the morphological findings seen in APMF. Clinically, APMF can be separated from MOS by its more abrupt onset with fever and bone pain. In APMF. histology of the BM shows more numer- ous megakaryocytes and, on average, a higher number of blasts than what are found in AAEB. Cases of AAEB-2-F. ex- cept for their usually less acute clinical presentation, may be indistinguishable from APMF 116511. APMF is distinguished from PMF by the more numerous blast cells in the former and the distinct cyto- logical characteristics of the megakaryo- cytes in the latter (See Chapter 2). The presence of a metastatic malignancy or, rarely a lymphoid disorder can be ex- cluded by studies with appropriate anti- bodies. Postulated normal counterpart Haematcpoietlc stem cell. The fibroblastic proliferation is secondary. Prognosis and predictive factors The disease is usually associated with poor response to chemotherapy and usually only a few months survival 11651,21241. Acute myeloid leukaemia, Il(){ otherwise specified 139
  • Myeloid sarcoma Definition A myeloid sarcoma is a tumour mass con- sisting of myeloid blasts with or without maturation occurring at an anatomical site other than the bone marrow (BM). Infil- trates of any site of the body by myeloid blasts in leukaemic patients are rot clas- sified as myeloid sarcoma unless they present with tumour masses in which the tissue architecture is effaced ICD-Ocode Synonyms Extramedullary myeloid tumour; granulo- cytic sarcoma: cmorona Epidemiology There is a predilect ion for males and last decades ctute. The mare.temaie ratio is 12 :1. The median age is 56 years (range. 1 month-89 years) 1663. 17421. Etiology Thesame as for acute myeloid leukaemia (AMl) and myeloproliferative neop lasms (MPN). Sites of involvement Almost every site of the body can be in- volved , the skin, lymph node, gastro- intestinal tract, bone, soft tissue and testis being more frequently attectec 1663. 17421. In less than 10% of ca ses. myeloid sarcoma presents at multiple anatomical sites 1663, 17421. Clinical features Myeloid sarcoma may occur de novo: its detection should be considered as the equivalent of a diagnosis of AML. It may precede or coincide with AML or repre- sent acute blastic transformation of myelodysplastic syndromes (MDS), MPN or MDS/MPN 1663, 17421. Finally, myeloid sarcoma may also be the initial manifestation of relapse in a pa tient with previously diagnosed AML, regard less of blood or 8M findings 1t7421. Morphology A myeloid sarcoma most commonly con- sists of myeloblasts with or without fea- tures of promyeloc ytic or neut rophilic maturation that partially or totally efface the tissue architecture. In a significant SA Pileri A. Orazi B. Falini proportion of cases, it displays rnyelo- monocytic or pure monoblastic morphol- ogy 1663. 17421. Tumours with trilineage haematopoiesis Of predominantly ery- throid precursors or megakaryoblastsare rare and may occur in conjunction W1tt1 transformation of MPN 117421. Cytochemistry On imprints, cytochemical stains for myeloperoxidase (MPO), naphthol-AS(). chloroacetate esterase (CAE) and l'"Il;no specific esterase (NSE) may assist in differentiating granukx::ytic lineage (Mfl()+, CAE+) from rroooblasnc forms (NSf+~ In addition, CAE reaction can be applied to routine sec tions , although the results may depend on fixation and decalcifying agents. Immunophenotype On immunohistoc hemistry in paraffin sec- tions, CD68/KP1 is the most commonly expressed marker, followed in decreasing frequency by MPO, CD t 17, CD99 . CD6&' PG-M t , lysozyme, CD34, termin al de- oxvnucreoncvt transferase (TdT), CD56, CD6t/lAT/von Willebrand antigen, CD30, 140 Acute myelotd leukaemia and related precursor neoplasms
  • glycophorin,.and CD4 117421. Foci of plasmacytoid dendritic cell differentiation (C0 123+) are occasionally observed in cases carrying inv(16) 117421. The com- bination at the above mentioned markers allows the recognition of tumours with a more immature mye loid phenotype, as well as of cases with mveromonccvtrc. monoblastic, erythroid or megakaryocytic differentiation. Exceptionally, aberrant anti- genic expressions are observed (cyto- keratins. B- or T-cell markers). Cases that meet cntena for mixed phenotype AML are not classified as myeloid sarcoma (See Chapter 7). Flowcvtorenlc analysis on cell suspensions reveals posmvmesfor C013. C033. C0 117 and MPO in tumours withmyeloid differentiation. and for CD14. COl 63 and COlle in the monoblastic ones. Genetics By FISH andlor cytogenetics, chromoso- mal aberrations are detected in about 55% of cases. They include rnonosomy 7, trisomy 8, MLL-rearrangement. inv( 16). trisomy 4, monosomy 16, 16q-, sc-. 2Oq- and trisomy 11 {17421. About 16% of cases carry evidence of NPM 1mutations as shown by aberrant cytoplasmic NPM expression 1663. 666/.The t(8;21Xq22;q22) observed in paed iatric series seems to be less frequent in adu lthood 1' 742, 19781. Differential diagnosis The major d ifferential diag nosis is with malignant lymphoma, The diag nosis of myeloid sarcoma is validated by the results of cytochemical and/or immuno- phenotypic analyses. These allow the distinction of myeloid sarcoma. from: 1ym- phoblastic lymphoma, Burkitt lymphoma . diffuse large B-cell lymphoma. small round cell tumours, particularly in children, and blastic plasmacytoid dendritic cell neo- pla sm 11742/. These tumours must be di stinguished from non-effa cing tissue infiltrates by AML or MPN Postulated normal counterpart Haernatopoietic stem cell. Prognosis and predictive factors The cli nical behaviour and response to therapy seem not to be influenced by any of the following factors: age , sex, anatom- ical site(s) involved. de novopresentation, clinical history related to AMl. MDS or MPN , histological features. immuno- phenotype and cytogenetic findings 117421. Patients 'Nho undergo allogeneic or aUIOOgous BM transplantation seem to have a higher probab ility of prolonged survival or cure 1268. 17421. MyelOId sarcoma 141
  • Myeloid proliferations related to Down syndrome I. Baumann C M, Niemeyer AD. Brunning O.A. Arber A, Porwit Individuals with Down syndrome (OS) have an inc reased risk of leukaemia com- pared to non-OS individuals 1716. 23651. The increased risk is variously estimated at 10 to 100 Iold. The increased risk ex- tends into the adult years. In addition to the increased Incidence, the ratio of acute lymphoblastic leukaemia (ALL) to acute myeloid leukaemia (AMl) in OS children less than 4 years of age is approximately equal, 1.0:1.2, compared 10 non·DS chil- dren in the same age group in which the ratio is 4:1. There is an approximately 150 fold increase in AML in OS children less than 5 years of age; 70% of the cases of AMl in OS children less than 4 years of age areacute megakaryoblaslic leukaemia in contrast 10 the 3-6% incidence otttns to m of leukaemia in r"lOfl-DS child ren. The acute megakaryob laslic leukaemia which occurs in OS children has somewhat unique morphologic, immunophenotypic, molec ular and clinical characteristics which distinguish it from other forms of acute megakaryob laslic leukaemia, in- eluding GATA 1 mutations 1635. 1362J These various features serve as the ra- tionale for the recog nition of this form of leukaemia as a distinct type in the WHO classification, In addition to the unique characteristics of the pred ominant form of AM L in OS children less than 4 years of age , approximately 10% of OS neonates manifest a haematolog ic disorder referred to as transient abnormal myelopoiesis or transient myeloproliferative otsoroer which may be morphologi cally indistinguishable from the predominant form of AML in OS children 1271, 14091,This disorder resolves spontaneously over a period of several weeks to 3 months, In 20-30% of the af- fected cases. non-remitting acute mega- karyoblastic leukaemia subsequently develop s in t to 3 years. It is important to recog nize that although the atoremen- nooeo disorders have received the most attention in OS patients, they occur in a specific age group and other forms of acute leukaemia, both ALL and AML. af- fect OS individuals. The overall increased risk for OS individuals includes all types. The same approach lor characterizing the specific type of teukaemia in OS patients must incl ude the same ca reful morpho- loqic, lmmunoonenotvoic. cytogenetic and molecular eval uation as in non-OS individu als to ensure that appropriate therapy is administered 124891. Transient abnormal myelopoiesis Definition Transient abnormal myelopoiesis (TAM) is a unique disorder of Down syndrome (OS) newborns that presents with clinical and morphologic find ings indistinguishable from AML. The blasts have morphologic and irrrnunologic features of megakaryo- cytic lineage. ICD-Ocode The provisiona l code proposed for the fourth edition ofICO-O is 9898/1. Synonym Transient myeloproliferative disorder. Epide miology Transient abnormal myelopoiesis occurs in approximately 10% of OS newborn s: it uncommonly occurs in phenotypically normal neonates with trisomy 21mosaicism, Clinical features At presentation, thrombocytopenia is most common; other cytopenias are less fre- q uently encoun tered, There may be a marked leukocytosis and the percentage of blasts in the peripheral blood (PB) may exceed the blast percentage in the bone marrow (BM ). Hepatosplenomegaly may be present. Rarely, clinical complications incl ude cardiopulmonary failure. hyper. viscosity. splenic necrosis and progres- sive hepatic fibrosis 15921. The process in the majority of patients undergoes spon- taneous remission Within the first three months of life; a few chil dren experience life threatening oreven fatal clinical com- plications. .- Fig. 6.41 Blood 5me¥ from a ore day-old Ilfanl ... 00rM'l synOrome and lransieotabnofmal ~ The PBcontailed 55% f*Ists. C)1Jgenek studystx.:l horny 21as hi soleabnormality. The process ~ ~1MIl" aperiod ofbJ" weeks. Morphology and immunophenotype The morphologic and immunophenotyplC features of TAM are similar to those ofthe blasts in most cases of OS AML. Peri- pheral blood and 8 M blasts ouen have basophilic cytoplasm with coarse be- sophilic gra nules and cytoplasmic bleb- bing suggestive of meqakervobiasts. Some patients have PB basop hilia; ery- throid and megakaryoc ytic dysplasia is often present in the BM 12711. Blasts in TAM disp lay a cha racteristic immuno- phenotype 11 25 11. In most cases the blasts are positive for C034, CD56. C0 117, COt3, CD33, CD7, CD4 dim, C041, C0 42, TPO-R, lL-3R, C036, COOt, C071, and are negative for myeioperc» case. C0 15, C0 14 and glycophorin A The blasts in approximately 30% of cases are posi tive for HLA-DR. Antibod ies to C041 and CD61 may be particularly useful in identifying cells of megakaryocytic lineage in immunohisto- logic preparations. Genetics In addition to trisomy 21,acquired GATAI mutations are present in blast cells of TAM 1635,942,2347/. While gene eneysnoes have suggested differences in expression between AM L of OS and TAM. these findings have not yet been cootsrreo 1258, 1298, 1439/. 142 Acute myeloid leukaenlla and related precursor neoplasms
  • A ·..:....."!;;.4 . ....,"-' FIg.6.42 UyeIoid 1eukaerr'U associaledwilhDown syrdome ina two year-dd d*l. A Bone marrow smear.ThePB and8M smearsc:ontarled ITIJIbpIe blastsas ~_ loWry ollie bIaslscontained runetOUS coarse basoIlI*CI:lIcAnd gJarUes. wtidl were myeloperoxidase ~_ Cy!OgenetJC sludy et1Mbmeshowed trisomy 8 inali:lIbDn kllrJsomy 21. BBone marrow trephrle biopsy !rom !he same pabenl There aft! I'II.I'flef'OI. blasts andoccasional megakaryocyles induding one with aIIOIHobated IllJl::llM. C AnirTmJnl> IJst*9C readJon WIth CD-61 antibody. There are r...metOUS readJng eels indtdng otMous megakatyocyles andsevetaI smaIer eels. Fig. 1.'3 SedicI'I d iWI atldl:ri'III ~ nodeIn:lm • eNd wrltl Ck:Jr,yrJ syncmnelnl ac:uIe megakar'yobl9sbc Ieo..*aerTia The I'lXIe is~ ~ byb8sls wifloccasicI'laI ~. saned.n::nae dyscllasIc. Prognostic and predictive factors Although the dIsorder is characterized by a high rate of spontaneous remission, rco-nansent AML develops 1 103 years later in 20-30% ot mese children 125031. Indications lor chemotherapy in TAM are not firmly established, Myeloid leukaemia associated with Downsyndrome Definition Individuals with OS have a 50 fold in- crease in incidence of acute leukaemia duringthe first 5 years of life compared to non-OS individuals. Acute myeloid leukaemia in OS is usually an acute megakaryoblaslic leukaemia, accounting for 50% of cases of acute leukaemia in OS individuals beyond the neonatal period. There are no biok>gical differences in OS individuals between myelodysplaSbC ~ drome (MOS) and overt AMl; therefore, a comparable diagnostic differentiation al- gorithm is not relevant and would have no prognostic or therapeutic consequences. Since this type of disease is unique to children with OS the term myeloid leukaemia of OSencompasses bOthMOS and AML. ICD-Ocode The provisional code proposed for the fourth edition of ICo-O is 9898/3. Epidemiology The great majority of children with OSwith myeloid leukaemia are under 5 years of life. About 1- 2% of children with OS will develop AML during the first 5 years of Iile. Children with OSaccount lor - 20% of all paediatric patients with AMUMOS 1271.592.9081 _Myeloid leukaemia of OS occ urs in 20-30% 01children with a prior history of TAMand the leukaemia usually occ urs 1-3 years after TAM. Sites of involvement Blood and BM are the princip le sites of in- volvement. Extramedul lary involvement, mainly of spleen and liver, is almost al- ways present. Clinical features The disorder manifests predominantly in the first 3 years of life, The clinical course in children with tess than 20% blast cells in the 8M appears to be relatively indo- lent and presents initially with a period of thrombocytopenia. A preteokaemc phase comparable to refractory cytopenia of childhood (RCG)generally preceeds MOS with excess blasts or overt leukaemia. Morphology In the pre-leukaemic phase. which can last for several months, the disease has the features of RCC (See Chapter 5) lack- ing a significant increase of blasts. Ery- throid cells are macrocytic. Dysplastic features may be more pronounced thanin primary refractory cytopenia. In cases of AML, blasts and occasionally erythroid precursors are usually present in the PB. Erythrocytes often show considerable anrscooikllocytoele. some- times dacryocytes. The platelet count is usually decreased and giant platelets may be observed, In the 8M aspirate, the morphology of the leukaemic blasts shows particu lar fea- tures with round to slightly irregularnuclei and a moderate amount of basophilic MyefOid proliferatIOnsrelated to Downsyndrome 143
  • cytoplasm; cy toplasmic blebs may be present. The cytoplasm of a variable num- ber of blasts contains coarse granules re- sembling basoph ilic granules. The granules are generally myeloperoxidase negalive. Erythroid precursors often show megaloblastic changes as well as dys- plastic forms, including bi-Of trinucleated cells and nuclear fragments. Dysgranulo- poresrs may be present . The 8M core may show a dense network of reticulin fibres, making adequate 8M aspiration difficult or impossible. Erythro- poiesis may be increased in cases with a lowblast percentage and decreases with disease progression. Maturing cells of neutrophil lineage are usually decreased. In cases WIth a dense blast cell infiltration rare dysplastic megakaryocytes may be seen. In other cases of acute megakary- ootasnc leukaemia. megakaryocytes may be markedly increased with clusters of dysplastic small forms , micromegakaryo- cvtes and occasionally an increase in promegakaryocytes. Immunophenotype Leukaemic blasts in acute megakaryocytic leukaemia of OS display a similar immuno- phenotype to blasts in TAM /125 11. In most cases, the blasts are posi tive for CD 11?, CD 13, CD33, CD?, CD4, CD42. TPO-R, IL-3R. CD36, CD41, CD61, CD7 1. and are negative for myeloperoxidase, C0 15. CD1 4 and glycophorin A. How- ever, in con trast 10 TAM, CD34 is negative in 50% of cases and approxi- mately 30% of cases are negative for CD56 and CD4 1. Leukaemic blasts in other types of AML in OS display pheno- types corresponding to the particular AML category Antibodies to C041 and C061 may be particularly useful in identIfying cells of megakaryocytic lineage in irrvnunohisto- logic preparations. Genetics In addition to trisomy 21, senate rmtatcos 01 the gene encoding the transcnpnon factor GATA1 are considered pathogno- monic of transient abnormal mveicooeeis of Down syndrome (TAM) or Mo S/AMl oi OS 1835. 942, 13621. Children above the age of 5 with myeloid leukaemia may not have GATA 1 mutations and such cases should be considered as 'conventional" MDS or AML. Trisomy 8 is a comrTlO'l cytogenetic abnormality in myeloid leukaemia of OS occurring in 13-44% at patients 1908, 9181. Monosomy 7 is very rare in Ds-associateomyeloid leukaemia Postulated nonnal counterpart Haematopoietic stem cell. Prognosticand predictive factors Clinical outcome for young children WlI!l OS and myeloid leukaemia with GATAI mutations is unique and is associated with a better response to chemotherapy and very favourable prognosis corceec to non-OS children with AML 112501. rte children should be treated on DS-specrllc protocols. Myeloid leukaemia in olderOS children with GATA' mutation has a poorer prognosis comparable to AMl i'l patients without OS {7511. 144 Acute myeloid leukaemia and related precursor neoplasms
  • Blastic ·plasmacytoid dendritic cell neoplasm F.Pacchem D.M. Jones T. Petrella Ebology There are currently no clues to the etro- bgy 01 BPDC, but its association with myelodysplasia in some cases may suq- geS! a related pathogenesis. There is no association with Epstein-Barr virus (EBV). Sjoonyms Blasbc NK-celilymphoma 11039/. aqran- iJaf CD4. natural killer cell leukaemia 12771. blastic natural killer leukaemia/lym- pt'(ma 576J, aaranurar CD4 +CD56+ reematooerrmc neoplasm 117361ltumour 19201 Epidemiology This is a rare form of haematologic neo- plasm. without any known racial or ethnic predilection. It has a male/female rano of 33:1; most patients are elderly, with a «eererecnan age at diagnosis of 61-67 years. but it can occur at any age, in- Ckldlngchildhood 1702. 920 ,1031 1. Definition Blastic plasmacytoid dendritic cell (BPDC) recoesm is a clinically aggressive tumour defived from the precursors of otasrnacv- klid dendritic cells (also known as protes- SlOnaI type 1 interferon producing cells or plasmacytoid morocvtes). with a high tre- cuencv of cutaneous and bo ne marrow (8M)involvement and leukaemic dissem- ination. leukaemia) with massive nod al or extra- nodal localization of plasmacytoid den- dritic cells, in which the plasmacytoid oeoouc cells are rrnphoIogica/ly mature and C056 negative123351. Morpho<ogy BPDC is usually characterized by a dif- fuse, monomorphous infiltrate of medium- sized blast ce lls with irregular nuclei, fine chromatin and one to several small nu- cleoli . The cytoplasm is usually scant and appears grey-blue and ag ranular on Giemsa stain. Mitoses are variable in number. but rarely prominent; angiOlnva- sion and coagulative necrosis are absent. In cutaneous inlihrates, tumour cells pre- dominantly occupy the dermis, sparing the epidermis, but eventually extending to subcutaneous lat. l ymph nodes are dif- fusely involved in the interfollicular areas and medulla, with a leukaemic pattern of infiltration. Bone marrow biopsy may show either a mild interstitial infihrate only delectable by immunophenotyping , or massive infiltra- tion; residual haeroatcooetc tissue may exh ibit dysplastic features, especially in megakaryocytes 11735}. On PB and BM smears tumour cells may show cytoplasmic rmcrovacuoles localized along the cell membrane and pseudopodia. Cytochemistry BPDC tumour cells are non-reactive lor naphthol-butyrate esterase and perox i- dase cytochemical reactions. Sites of involvement The disease tends to involve multiple sites . with a predilection for skin (almost 100% of cases). followed by 8 M and peri- pheral blood (PB)(60-90%). and lymph nodes (40-50%) 1920, 17351. Clinica l features The patients usually present with asymp- tomatic solitary or multiple skin lesions that can be nodules, plaque s. or bruise- like areas, Regional lymphadenopathy at presentation is common (20%); PB and BM involvement can be minimal at pres- entation. but invariably develops with progression of disease. Cytopenias (espe- cially thrombocytopenia) can occur at di- agnosis, and in a minority of cases can be severe, indicating BM failure 1702, 9201. Following initial response to chemother- apy, relapses invariably occur, involving skin alone. or skin associated with other sites. including soft tissues and the cen- trat nervous system. In most cases a ful- minant leukaemic phase ultimately develops 17021. About 10-20% of cases of BPOC are as- sociated with or develop into a mvero- monocytic leukaemia or acu te myeloid leukaemia 1702, 920, 924 , 1142. 1735, 18301. These second teukaermas can evolve from underlying myelodysplasia, or appea r suddenly upon prog ression or relapse 1702, 924,1 1421· BPDC must be distinguished from the occasional association of a myeloid neo- plasia (especially chronic myeIornonOCylic 9727/3ro<l code , "'';I''~CIoJii. r..•.-" 8IastJC pIasmacyIoid llendnOC eel neoplasm. A Ski'I tI.I'I'lWfand plaques. B The inIiIlrate diftu$ety imoIYes !he demis andedendstl subc:Wnews fat. butspareslIle 1Pde!fM, CThe neoplasbc eels are mediI.m-sized. wiIhlineetwomatin and scanly cytoplasm. reminiscentof undlf!erentiated blasts, Blastic plasmacytoid dendrrtic cell neop lasm 145
  • Immunophenotype Tumourcells express CD4,CD43, CD45RA and CD56, as well as the plas macytoid dendritic cell-associated antigens CD123 (interleukin-3 a-chain receptor), BDCA-2/ CD303, TCU , CLA (cutaneous lympho- cyte-associated antigen) and the inter- feron-a dependent molecu le MxA (92, 920,924, 1735-1737, 1739, 1747, 1830, 22791. Rarely, the C056 antigen can be negative, which does not rule out the di- agnos is if CD4, CD123 and TCl1 are present. Tumours that share some but not all immunophenotypic features of BPDC may be better classified as "acute leukaemia of ambig uous lineage". C068 (an antigen typical ly found on nor- mal plasmacytoid dendritic cells) is ex- pressed in 50% of cases , in the form of small cytoplasmic dots (1735, 1739J. Among lymphoid and myeloid-associated antigens, CD7 and C033 are relatively common ; and some cases have shown expression of C02, CD36 and CD38, while CD3, CDS, CD13, CD16, CD19, CD20, CD79a, LAT(linker for activation of T cells) , lysozyme and myeloperoxioase are regularly negative, Granzyme B, which is regularly found in normal plas- macytoid dendritic cells , has been demonstrated on flow immunophenotyp- ing and mRNA analysis in BPDC [395, 820. but it is mostly negative on tissue sections, similarly to other cytotoxic molecules such as oertonn and TIA1, Terminaldeoxynucleotidyl transferase (TdT) is expressed in about one third of cases , with positivity ranging between 10% and 80% of cells; CD34 and CD117 are nega- tive. EBV antigens or EBV-encoded small nuclear RNA (EBER) are not found. Except for CD56 and TdT, the immuno- phenotype of BPOC largely overlaps with that of plasmac ytoid dendritic cells oc- curring in reactive lymph nodes and ton- sils [654}. Because other heematotoqic neoplasms (such as acute myeloid leukaemia, extranodal NK/T-eeil lymphoma, nasal type and mature T-cell lymphomas), with or without skin involvement, may ex- press CD56 with or without CD4, an extensive immunohistochemical and/or genetic analysis is mandatory before a definitive diagnosis of BPDC is made (92, 173,386,920, 1386). Genetics J-ceu and a-cen receptor genes are usu- ally germline {92, 1735, 1830}, except for a few cases that showed T-cell receptor gamma rearrangement 1920, 1735}. Two thirds of patients with BPDC have an ab- normal karyotype: specific chromosoma l aberrations are lacking, but complex kary- otypes are common; six major recurrent ch romosomal abnormalities have been recognized, including 5q21or 5q34 (72%), 12p13 (64%), 13q 13-21 (64%), sqza-qter (50%), 15q (43%)and lossofchrornosome9 (28%) 11279,1737, 18301. Geneexpression profiling and array-based comparativege- nomic hybridization have shown recurrent deletions of regions on chromosome 4 (4q34), 9 (9p 13-p11 and 9q12-q34) and 13 (13q 12-q31) that contain several tu- mour suppressor genes with diminished expression (RB 1, LATS2), while elevated expression of the products of the OrtCG- genes HES6, RUNX2 and FLT3 is notas- sociated with genomic amplification (5781. 146 Acute myeloid leukaemia and related precursor neoplasms L
  • Postulated normal counterpart The normal counterpart is the precursor of the plasmacytoid dendritic cells . Data on anligen 1395. 396. 820, 920. 924. 1031 , 1051,1736, 1739.2279landchen"ll> kine receptor expression {18Sf, in vitro functional assays {18S, 3961. gene ex- pression profiling 15781. as well as on the tumour-derived cell line CAL-l 11361 1all point toward a derivation from the precur- sors of a special subset of dendritic cells, !he plasma cytoid dendritic cells 1356, 857,20591. These cells are distinguished by their production of high amounts of u - Interferon in humans 1357l; in the past. !hey have been defined with many differ- ent terms. such as lymphoblast, t-essocr- ated plasma cell , plasmacyt oid T-ceU and plasmacytoid monocyte {6541. The i'nmunophenotypic heterogeneity with re- gards 10 TdT and the association with myeloid disorders suqqests a multihn- eage potential lor some cases 01BPOC. Prognosis and predictive factors The c linical course is aggressive . with a median survival of 12-1 4 months. irre- spective of the initial pattern of disease. Most cases (80- 90%) show an initial re- sponse 10 mulliagent chemotherapy, but relapses with subsequent resistance to drugs are regularly observed. Long-last- ing remissions have been documented in spor adic cases, usually occurring In young patients who have been treated with acute leukaemia-type induction ther- apy, followed by allogeneic stem cell transplantation in first complete remission 192.920, 17351· Blastic plasmacytoid cencntc cell neoplasm 147
  • CHAPTER 7 Acute Leukaemias of Ambiguous Lineage
  • Acute leukaemias of ambiguous lineage M,J Borowitz M,-e, Bene Nt.. Harris A. Porwit E. Matures Table 7.01 RllQuiremefils for assigrlingmore than onelineage toa Single ~asl populaton. 8 lineage (multiple antigens requnct ) Strong C019wiltla1ieas11 oftnefclowing strr.Tf/'I e~ . CD79a. C)1OpIasrrMc C022. COlO "Weak CD19withill least 2oIlhe IoIowilg5IfOn!lIY exp!&S:Sed: C079a,cyqMsmic C022.CD10 Myeloid lineage ~xidas.e (fbwcylomeIfy, immunohislOChemistry orcytoChemistry) "Mi:Inocy1icdifterentiaticl'l (al least2of lhe kllIowrng: NSE. CDlle,C014, CD64 ,~) Tlineage Cytoplasmic COO (!kM' cytomeIry wi1l'l antibodies 10COO epsilon etIatn: irnn~nolliStoehemistry USIIIg polydonaI <W1b-C03 <W1tbody maydeled CD3zeta chain, wtid'I is not T<:eII spec::ific) "SOOace COO (rareW1 mixed pIlenoIype lClJIe leUkaen'liasj most frequently shown by flow cvtomeuc positivity, on blast cells coexpressing 1ym- phoid markers. The myeloid lineage ann- gens CD 13, CD33 and CD l 17 are no! specific enough to allow identification cA a mixed phenotype leukaemia. 3) When there is a single population ot cells that by itself would meet criteria forB Of T-All in which the blasts also show tXI- equivocal evidence of monoblastic differ- entiation: either diffuse positivity !t;) non-specific esterase or expression cA more than one monocytic marker such as CD11c, CD 14, CD36, CD64 Of lysozyme The first of these three instances wooId previously have been considered -bilin- eage leukaemia" while alternatives 2 and 3 represent what would have been termed "biphenotypic leukaemia". The t-een component of an MPAl is re- cognized by strong expression of cvto- plasmic CD3, either on the entire blast population, or on a separate suo ocoua- non of leukaemic cells. Surface CD3, thOugh rare, also ind icates T-cell lineage, Expres sion of cCD3 is best determined by flow cytometry using relatively brighl fluorophores such as phycoerythrin or er lophycocyanin, and should be as bright or nearly as bright as that of normal resi- dual T cells present in the samp le. T-cell lineage can also be demonstrated by CD3 expression on blasts by immunohisto- chemistry on bone marrow biopsies, though it should be noted that polyvalent mye logenous leukaemi a (CML) in blast crisis, MDS-related AMl and therapy- related AMl should be classified pnma- rily as such, even if they have a mixed phenotype, with a secondary notation that they have a mixed phenotype. The diag nosis of ambig uous lineage leukaemias rests on irnmunophenotyping . Flow cytometry is the preferred method for establishing the diagnosis, especially when a diagnosis of MPAl is de pendent upon demonstrating coexoressoo of 1ym- phoid and myeloid d ifferentiation antigens on the same cell. Cases in which the dia- gnosis rests on demonstration of two dis- tinct leukaemic populations with a different phenotype may also be established by immunohistochemistry in tissue sections, or with cytochemical stains for myeloper- oxidase on smears coupled with flow cvto- met ry to detect a leukaemic B or T lymphoid population. The myeloid component of an MPAL can be recogn ized in one of three ways: 1) When there are two or more d istinct pop ulations of leukaemic cells, one of which would meet immunopheno typic criteria for acute myeloid leukaemia {with the exception that this population need not comprise 20% of all nucleated cel ls} 2} When there is a sing le population of blasts that by itself would meet criteria for B acute lymphoblastic leukaemia (B-ALL) or T acute lymphob lastic leukaemia (T-ALl) and the blastsalsoexpressmyeloperoxidase, Acute leukaemias of ambigUOlls lineage encompass those leukaemias that show no clear evidence of differentiation along a single lineage. They include Ieukaemias with no lineage-specific antigens (acute undifferentiated leukaemia. AUL) and those with blasts that express antigens of more than one lineage to such a degree that it is not possible to assign the eukaefT'Wa to any o-e lineage with certainty (mixed phenotype acute ieukaermas. MPAL). The latter can either contain dis- Iinct blast populations. each of a different lineage. or one population with multi ple antigen s 01different lineages on the same cells. or a combination. Historically, there has been confusion both in the terminolog y and definition of MPAL. The term acute bilineal (or bilin- eag e) leukaemia has been applied to leukaemias containing separate popcta- .nons of blasts of more than one lineage, and the term biphenotyp ic leukaemi a to those containing a single population of blasts coexpressing antigens of more thanone lineage I885, l267, 1427, 2119}, although sometimes the ratter term also encompassed blnneaueukaemta. Here the term mixed phenotype acute leukaemia applies to this group of lesions in general, and , as defined below, the more specific terms B/myeloid (B/MY) and T/mye loid (T/MY) leukaemia to refer to reukeemras containing the two lineages specified, irrespective of whether one or more than one population of blasts is seen. Some well-defined myeloid leukaem ic entities may have irnrnunoonenorvplc features that might suggest that they be classified as Bimyeloid (BlMY) Of Tlmyeloid (T/MY) leukaemras. However, MPAL, as defined here, excludes cases that can be classified in another category, either by genetic or clinical features. These specif- ically include cases with the recurrent acute myeloid leukaemia (AML)·associ- etec uansiocenons 1(8;21), t( 15;17) or inv( 16); the first of these especially fre- quently exp resses muniple Bceu markers /22361. In addition, cases of leukaemia with FGFRI mutations are not con sidered TIMY leukaemias Cases of chronic 150 Acute ieckaenes of ambiguous lineage
  • Acute undifferentiated leukaemia Synonyms Acute leukaemia, NOS; stem cell acute leukaemia. Cytochemistry The blasts are negative for nweicoe roxl- case and esterase. Clinical featu res There are no features that distinguish this from other acute ieukaemias. Mixed phenotype acute leukaemia with t(9;22) (q34;q11.2);BCR-ABL1 ICD-O code The provisional code proposed for the fourth edition of ICo-o is 980613. Genetics There are too few cases descnbed to know whether any consistent genetic lesions occur. Clinical features Patients present with features similar to those of other patients with acute leukaemia. Though there are not enough data to be ce rtain, it is likely that they present with high white blood cell counts, similar to patients with Ph-s ALL. Postulated normal counterpart Haematopo ietic stem cell. Prognosis and predictive factors While anecdotal experience generally considers these leukaemias to be of poor prognosis, information is too scanty to make any defin itive statements. Definition This is a leukaemia meeting the criteria for MPAL in which the blasts also have the t(9:22) translocation or BCR-ABL 1 re- arrangement. Some patients with chronic myeloid leukaemia may develop or even presen t with a mixed blast phase that would meet criteria for MPAL, however this diagnosis should not be made in pa- tients known to have had CML. Epidemiology Although this is the most common recur- rent genetic abnormality seen in mixed phenotype acute leukaemia. it is a rare leukaemia, prob ably accounting for less than 1% of acute leukaemias. It occurs in both children and ad ults, but is more common in adults 1338 ,11 451. Mof'phology Many cases show a dimorphic blast population, one resembling Iymphoblasts and the OIher nwecotasrs. although some cases have no distinguishing features Cases generally do not show significant myeloid maturation; care shoold be taken about making this diagnosis in a case of 980 1/3ICD-O code Morphology The blasts have no morpholog ic features of myeloid differentiation. Epidemiology These leukaemfas are very rare, and nothing substantial is known about their frequency. Definition Acute undifferentiated leukaemia ex- presses no markers co nsidered specific for either lymphoid or myeloid lineage. Before categorizing a leukaemia as undif- ferentiated, it is necessary to perform irn- munophenotyping with a comprehensive panel of monoclonal antibodies in order to exclude leukaemias of unusual line- ages, such as those derived from myeloi d Of plasmacytoid dendritic cell precursors, NK-cell precursors, basophils or even non-baernatocoietrc tumours Sites of involvement Bone marrow and blood . There are too few cases to know whether there is a predilect ion for other sites. Immunophenotype These reukaemas typically express no more than one membrane marker of any given lineage. By definition , they lack the T or myeloid lineage specif ic markers cC 03 and MPO and do not express B- ce ll specific markers such as cCD22, cC079a or strong C019. They also lack specific features 01other lineages such as megakaryocytes or plasmacytoid den- ontrc ce lls. Blasts otten express HLA-oR. CD34 , and/or C038 and may be posi tive for terminal deoxynucleotidyltransferase. T-cell antibodies used in immunohisto- chemistry also react with the zeta (~) Chain of the t-een receptor present in the cytoplasm of NK-cells, and are thus not absolutely t-een specific . In contrast to what is described above with myeloid and t-een lineages, no sin- gle marker is sufficie ntly specific to indi- cate B-cell differentiation with certainty, so that a constellation of find ings is needed. Been differentiation can be recognized v.tIen there is a distinct subpopulation of cells that by itself meets criteria for B-ALL When only one population of cells is pres- ent. then B-lineage assignment requi res either 1)strong Co19 expression coupled with strong exp ression of at least one of the following antige ns: C01O, Co79a or cCD22; or 2) weak CO 19 expression cou- pled with strong expression of at least two of the following : C01O, Co79a and cCD22. Rarely, a case may be assigned as B lineage even If C019 is negative, though care must be taken when doing this because of the relative lack of speci- !iclty of C010 and Co79a. Cases of MPAL based on one criterion at diagnosis (e.g. 'biphenotypic leukaemia") may change over time or at relap se to the other (" bilineage leukaemia"), or vice versa. Also, following therapy, persistent disease or relapse may occur as either pure ALL or AML. Some cases of what 'as been termed "lineage switch" 11684, 18251may reflect this phenomenon Ambiguous lineage leukaemias are rare and account for less than 4% of atl cases olacute leukaemia. Many cases of what have been reported as undifferentiated 'eukaemia can be demon strated to be eokaemtas of unusual lineages, and 'TIany ca ses of what have been reported as biphenotypic acute leukaemias may in tact represent acute lymphoid ormyeloid letJkaemias With cross-lineage ant igen expression, so that the actual frequency may even be lower, These leukaerruas occur both in children and adults but -rore frequent ly in the latter, although some subtypes of MPAL may be more common in children 11145, 16711. Avariety of genetic lesions have been re- ported in ambiguous lineage leukaemi as, especially MPAL. Two of these, the t(9:22) (Q34;q 1l ) BCR-ABL 7 translocation, and sansrocanons associated with the MLL gene occur frequently enough and are associated with distinctive features that lhey are considered as separate entities. Acute leokaernias of ambiguous lineage 151
  • Fig.1.01 ElJrnyeIoid I8ulalInN with 1(9.22Nq34;q11 2). Theblasts vary from smaI ~ iIppeWVlg bIasIs kl ~ blasts WIlh dispersed c:lVl:lmaIin, prorninefJl nudeoIi anda Il'llXlefllte ann.n ofpale ~.• Immunop henotype In the majority of cases it is possible 10 recognize a lymp hoblast population With a CD19-positive , CDlO-negative B pre- cursor (pro-B) irnmuncphenotype , fre- quently positive for CD15. Expression01 other B markers such as CD22 and CD79a is often weak. In addition to this, cases also fulfil criteria lor myeloid line- age as defined above, most comrnonly via demonstration of a separate papUa. tion of myeloid. and usually monobIaSIJC leukaemic ce lls 1167 1. 23711. Coexpes- sian of myeloperoxidase on Iymphold blasts is rare. MLL translocations can also produce T.ALL, so that it is thOOfeticaly possible that T/myeloid Ieukaemias ewa occur, although these have not been reported. • Mixed phenotype acute leukaemia with t(V;11q23); MLL rearranged myeloid leukaemia with maturation that also expresses lymphoid markers, be- cause such a pattern may be seen in pa- tients with blast phase 01CML. Irrvnunopheootyp The great majority 01cases have blasts meeting criteria tor 8 and myeloid lineage, as described above , though some cases have T and myeloid blasts. Triphenotypic leukaemi a has also rarely been reported . Genetics All cases have either the 1(9;22) detected by classical karyotyping. or the BCR-ABL1 translocation detected by FISH or PCR. Many cases have additional cytogenetic abnormalities, and often have complex karyolypes. Postulated normal counterpart Murnootent haematopoietic stern cell. There is no evidence thai this leukaemia derives from a di fferent cell from other cases of Ph+ acute leukaemia. Prognosis and pred ict ive factors This type of leukaemia has a poor oro- gnosis; it appears to be worse than that of other patients with MPAL {1 145 1, It is not clear whether the prognosis is worse than that of patients with Ph+ ALL, or if dif- ferent therapy can improve outcome. There are no known factors among pa - tients with this leukaemia that can pred ict who will do better or worse. It would be expected that imatinib and related tyro- sine kinase inhibitors might be useful in the treat ment of this type 01 leukaemia; howeve r. there are no data available to state this with certainty. Definition This is a leukaemia meeting requiremen ts for mixed phenotype acute leukaemia in which the blasts also have a translocation involving the MLL gene. Many cases of ALL with MLL transiocauons express myeloid-associated antigens, bu t these should not be considered MPAL unless they meet the specilic criteria noted above. ICD-O code The provisiona l code propo sed for the fourth ed ition of ICo-O is 980713. Epidemiology This is a rare leukaemia that is more com- mon in children than in adults. As with AL L or AML with MLL rearrangements, this leukaemia is relatively more common in infancy 11 145, 16711. Clinical featu res Patients present similarly to other patients with acu te leukaemia. As with other acute ieukaemras with MLL transtcceuons. high white blood cell counts are common. Morphology Most commonl y these leukaemias display a dimorph ic blast population , with one population clearly resembling monoblasts and the other resembling Iymphob lasts. However. in other cases they may have no distinguishing features and appear only as undifferentiated blast cells. Cases in which the entire blast population is monobtasnc are more likely to be AML with an MLL translocation. Genetics All cases have rearrangements of se MLL gene, with the most corrmon partner gene being AF4 an chromosome 4 bafld q21 1338. 16711. rranstocanons t(9:111 and t(1 1;19 ) have also been reported The rearrangement may be detected either by standard karyotyping orby FISH with an MLL breakapan probe or, less commonly, by PeR. Cases with deletions 01 ch romosome 11Q23 detected by karyotyping should not be considered in this category. The MLL translocation may be the only lesion present or there maybe other seconda ry cytog enetic or rrolecu- lar ab nomaunes although no additiooal genetic lesions common to multiple cases have been descr ibed Progn osis and predictive factors This is a poor prognosis leukaemia 11145, 23711. Patients with B/myeloid leukaemia with MLL translocations are often treated differently from patients diagnosed witn ALL with MLL transtocatlons. but there is no evidence that this is necessary or helpful. Mixed phenotype acute leukaemia, B/myeloid, NOS Definition This leukaemia meets criteria for assign. ment to both B and myeloid lineage as described above. but in which the btass lack the above-mentioned genetic abrc- mantes. 152 Acute 'eokaenes of ambiguous lineage
  • ICD-O code The provisional code proposed for the fourth edition of ICD-O is 9809/3. Prognosis and predictive factors B/myeloid leukaemia is generally cons id- ered a poor prog nosis leukaemia. Many patients meeting criteria lor B/myeloid leukaemia have the unfavourable genetic lesions and it has been suggested that this accounts for the ir poor prog nosis 111451. Whether adverse cytogenetic fea- tures entirely explains the poor outcome is not definitively established 11267, 23711. Postulated normal counterpart Multipotential naematopoeuc stem cell. There is growing evidence of a poss ible relationship between a-.cell and myeloid development suggesting either involve- ment 01a corrrnonprecursor, or of a pre- cursor of one lineage that has reactivated a d.tte renueton program of the other 11 127, 12401· 12p 11.2 abnormalities, del (5q) , structural abnormalities of 7, and numerical abnor- malities including near tetraploidy [338, 16711, Complex karyotypes may be seen There are insufficien t data in the literature to suggest that B/myeloid and T/myeloid leukaemias have different frequencies of oeterent genetic lesions, once the t(9:22) and MLL rearrangements have been ac- counted for. Mixedphenotype acute leukaemia, T/myeloid, NOS Epidemiology This is a rare leukaemia, probably ac- counting for less than 1% of leukaemias overall. It can be seen both in children and adults. It may be relatively more Ire- quent in children than is 8/myeloid acute leukaemia. Clinical features There are no unique clinical features. Definition This leukaemia meets criteria for assign- ment to both T and myeloid lineage as de- scribed above, but in which the blasts lack the above mentioned genetic abnor- malitie s. 8 COlOme Immunoph enotype Blasts meet the criteria for both Bclym- proto and myeloid lineage assignment listed above. Mveiooeroxioase-po sluve rnyeloblasts or monob lasts commonly also express other mye loid-assoc iated markers including CD13, CD33 or CD117. Expression of more mature markers of B- cell lineage such as CD20 is rare but may occur, particu larly when a separate population of B-cell lineage is identified {2371I, Genetics Most cases of B!myeloid leukaemia have c lonal cytogenetic abnormalities. Many d ifferent lesions have been demon- strated. though none is of such frequency to suggest specificity for this group of leukaemias. lesions that have been seen in more than a single case include del(6p), A --.f""""C" -- _ . 5: .~"( -., ~ . ·'Sf". -,j"-""- ;:...~ . .::<:-'' ...;. ' • ' I' :"'.: . . ..,.., Clinical features There are no unique clinical features, ICD-O code _ The provisional code propo sed for the ftxmh edition of ICD-O is 9808/3 Epidemiology This is a rare leukaemia, probably ac- counting for about 1% 01 leukaemi as overall. It can be seen both in ch ildre n and adults but it is more common in adults. . ,,,,;. .:,~.; . ' . :.~: C.. . ~ ).. I" of.,'"''':-1'', I Ii.,eN FITe Fig. 1.D2 FkIw L)'IOmetty in EIJmyeIoid 1euUemia. A C045'IS Side scatter display ShoWlIlQa ma,apopuIaIlon ofdin COt5+ !:*lsts. B~ 1111 bloe. residualnormal Bcells red and rnyeIoperoxidas posIbYe c:eIls (ndudong boIh tesls andI1ISiduaI nonnaI ceh)~. aeTheIk:et ~ CD19 andC022 areslrOI9Y expressed on!he BIym- ~ blasts.II"" CXlll1lIlable b!hal seenWIII'I residual nonnaI Ek:eIs (inred). 0 t.b;t of!he B-ceI blastsIaciMPO ...,manyhJu!1l nol aI of!he ~ blasts are MPO posiIi'Ie. There isasmaIpopUabonofblasts eoexpmsing 1I1l9rei MPO. """"""'"Most cases have blasts with no distin- (p.ishing features, morph060gicaJIy resem- bk'lg ALL, Of have dImorphic ocoutetcns with one resembling Iymphoblasts and eeother resembling myeloblasts. Acute leukaemias of ambiguous lineage 153
  • Postulated normal counterpart Mctnpotentrar haematopoietic stem cell. There is growing evidence 01 a possible relationship between T-c ell and myeloiO development suggesting either irM:llverne1: 01 a common precursor, or of a Iymphoicl precursor that has reactivated a myeloid differentiation program 11 127, 12401. Mixed phenotype acute leukaemia, NOS· rare types the t(9:22) and MLL rearrangements teve been accounted lor. PrognosiS and predictive factors Tfmyeloi d leukaemia is generally CQl'lSI' dered a poor prognosis IeU<aema a/Ito..I;1l data are limited on the outcome of trese patients distinct from other MPAl pawns. Patients with TtmyeIoid leukaemia teveI'l'A been treated un iformly. although carrO- nations of myeIoid-directed and IymptloiO- dtrected therapyhave been tried.andscm! patients may respond to one or the OCher, Some cases of leukaemia have been seen in which leukaemic blasts show clear-cut evidence of both T and B lineage com- mitment as defined above. This is a very fare phenomenon, with a frequency thatis likely lower than what has been reported in the literature. As strictly applied,the most recent EGIL crite ria for biphenotypic leukaemia (scores hig her tha n 2 in more than one lineage), which assigned 2 points to CD79a expression 153, 187) would likely overestimate the incidence of BIT leukaemia because CD79a can be de- tected in T-ALL 11 750). In assig ning B lin- eage to a case of T-cell leukaemia, CD79a and CD 10 should not be considered as evidence of B-celt differentiation. There have also been a few cases with e~i­ dence of trilineage (8, T and myeloid lin- eage) assignment. Overall there are too few cases of either of these to make any specific statements about clinical fea- tures, genetic lesions or prognosis. To date, there have been no reports of B or T/megakaryocytic or B or Tferythro- 1eukaerJias. Becauseit has been suggested that erythroid and megakaryocytic lineages are the earliest to branch off from the plur ipotent haematopoietic stem cell, lea...· ing progenitor cells with T, 8 and myeloid potential 1111, neoplasms of these core- nations of lineages may not occur. If It'ey , addition to cCD3, the t-een component frequently expresses other t-een markers including C07,CD5, and C02. Expression of surface G03 may occur when a sepa- rate population of t-een lineage is ioenu- fied 123711. Genetics Most cases have clonal chromosomal ab- normalities, although none is of such fre- quency to sug gest specific ity for this group ofleukaemias. There are insufficient data in the literature to suggest that B/MY and T/MY leukaemias have d ifferent fre- quenc ies of different ge netic lesions, once -Fig. 7.001 ThnyeIoid 1euIlaenU. ThIn ill . dimlrphicpop.MtionaI blasts wilhmany smaI~ ; largerblasts alsoMoe high ~sm 1'lIlio. h manatin aridinalnspicuous rndeoL """"""-Most cases have blasts with no cnstm- guishing features. morphologically re- sembling ALL, or have dimorphic populations. with one resembling lympbo- blasts and the other resembling myeio- blasts. lmmunophenotype Blasts meet the criteria for both T-lymphoid and myeloid lineage assig nment listed above. Myeloperoxidase-p ositive mvero- blasts or monoblasls commonly also ex· press other myeloid-associated ma rkers including CD13. CD33 or CD117. In 154 Acute leukaemlas 01 ambigUOUS lineage
  • F B CVTOPloSMlC f1"O rrrc cf'FOFlTC , . lymphoma may be considered in a case thai expresses C056 along with immature T-associated markers such as COl and C0 2 and even including cCD3, provided that it lacks B-eell and mye loid markers, t-een and IG receptor genes are in the germline configuration1128, 1174, t6601 and blastic plasmacytoid oenonuc cell leukaemia has been excluded .'..~ . .,',', C.;: - ., . . ,.~ ~ ...' .- , . _.- - .•.-, '. ..." ..' :... .' i "Ii, ,..,., ,...., ...,., SS L.. -'j'-'<':;;;,;,......:. .~.._, , ...., . .. ,., coe """" presentations that expressed NK-specilic CD94 lA transcripts have been described 113061. It is hoped that wider availability of more specific NK markers including panels 01 antiboclies against killer inrnunog lObuhn- like receptors (KIRs) will help clanfy this disease. but until then this is best coosrc- ereo a provisional entity. The diagnosis of precursor NK lymphoblastic leukaemia} Natural killer cell tymphobIastic leukaemia! ~phom. This neoplasm has been very difficu lt to define, and there is con siderable con fusion inthe literature, Contributing to the confu- sion is that many cases rep orted as NK leukaemia because of the expression of N-CAM (COS6) are now recognized to represent cases of plasmacytoid dendritic cell leukaemia 11735, 1736J. Similarly, the entityat mye loid/NK-cell acu te leukaemia 11980, 2129J, which has been suggested to be of precursor NK origin 11660) has a primitive immunophenotype that cannot be distinguished from acu te myeloid leukaemia with minimal differentiation, anduntil further evidence emerges these should be considered as cases of AML. Early in development, Nrc-celt progenitors express no specifi c markers 17331 or ex- pressmarkers that overlap with those seen inT-cell All.., including C07. C02 and even CDS and cytoplasmic C03 120701. so that distinguishing between T·ALl..and NK-cell tumours may be dillicult. More mature but rrore specific markers such as C016 are rarely expressed in any acute leukaemia. while some markers that might be con- sidered relatively more scecmc. but still expressed on NK progenitors. such as CD94 or C0161 17331 are not commonly tested. Some well characterized cases of NK precursor tumours WIthlymphomatous Under some circumstances leukaemias may express combinations of markers that do not allow classification as either AUL or MPAL as defined above. yet de- Iinitive classification along a single line- age may be difficult. Examples of such cases might include cases that express J-ceu-assoctated but nol r-cen-soecmc markers such as CD7 and COS without cytoplasmic C03. along with myeloid-as- sociated antigens such as C0 33 and CD13 without mvetoperoeoase. Such cases are best considered acute uncles- siliable teukaemes. With more extended panels containing newer, less commonly used markers, such leukaemi as might be able to be c lassified. do occur, it is possible that the definitions used here might not detect all cases, as these leukaemias would not be expected to express MPO. Otherambiguous lineage feukaemias Acute leukaemias 01ambiguous lineage 155
  • CHAPTER 8 Introduction and Overview of the Classification of the Lymphoid Neoplasms
  • Introduction and overview of the classification of the lymphoid neoplasms E.S. Jaffe N.L. Harris H. Stein E. Campo SA Pileri S.H. Swerdlow Fill, 1.01 There are IlIO mainarmsoftile immur.e system. the innate immur.e system, andthe adaptive immuroe system, Diagram shows respectiveroles 01 lymphocyte sutlpopulations inthe innate and adaptive immuneresponses NKcells,N K~ike Tcells,and yfo Tcellsfunction withothercelltypesincludinggranulocytesand macrophagesasafirst Hna ofdefense.These cellshavecytotoxicgranules (shown in red) oontainingperIorinandgranzymes The innateim- muoe system lacks specilidty and memory. Inthe adaptive invnuoe system, B00115 andToeIIs r&COgnizeanligeos (Ag) lhrough specific rec:e~ , immunoglobulin(Ig) and !he T-eeII recepD" rompIex(TCR) respediwly,Antigen presenta, tiontoTeels musttake pIac:e via anligen-presenling cells(APe) in lheconlellofIheappropnale majorhlstoa::lmpati- bihly c:omplex (MHC)ClassIIantigens. FiglIeR'I()Ijfied from {1035}. B-eeli lymphomas: lymphocyte differenti· ation and function Bccell neoplasms tend to mimic stages 01 normal B-cell differentiation , and the reo semblance to normal cell stages is a major basis for their classification and nomenclature. Normal B-eeU differentiation begins WIth precursor B cell s known as progenitor B celi sIB Iymphoblasts (blast ce lls thaI are the precursors of the ent ire B-eell line) , which undergo irTYnunoglobuhn IDI gene rearrangement and differentiate into man se surface immunoglobulin (slg) pes- itive (lgM+ IgO+) naive B cel ls via pre-8 cells with cytoplasmic ~ heavy chains and imma ture IgM+ B cells Naive B cells .that are often CD5 + , are sma ll rest ing lympho- cytes that circulate in the peripheral blood (PB) and also occupy primary lymphoid follicles and follicle mantle zones (so- called recirculating B cells) 11004A, 1152AI. Most cases 01mantle celilym- phoma are thought to correspond to CDS positive naive B cells 1994AI. On encountering antigen that fits their 51.1' face Ig rec eptors, naive B cells undergo transformation, proliferate, and ultimately ma ture into an tibody-secreling plasma cells and memory B cells. Translormed cells formed from nerve B cells that have encountered antigen may mature directly into plasma ce lls mat produce the early IgM antibody respon se to antigen. T-cell independ ent maturation can take place ou tside of the germinal centre 14241, Itis debated whether somatic hypermutatiOl"l of the IGH@ genes occurs during this encounter antigen in the context of the major histoc ompatib ility complex (MHC), and thus do not require antig en present- ing ce lls to initiate an immune response, The adaptive immune system is a more sophisticated type of immune response. It is specific for a particular pathogen; two key features of the adaptive immune re- sponse are specificity and memory This contrasts with innate immune responses whi ch are non-specific lor the target. and do not require or lead to immunological memory. Ag presentation to T cells in context of MHC Agopeafic -'''''on B + T cells even more rarely. lineage plasticity 11037, 13571, Thus, the normal counterpa rt of the neoplastic ce ll cannot at this time be the sale basis for the classification. IAdaptive immune system I Pathobiology of lymphoid neoplasms and the normal immune system There are two major arms of the immune system that differ, both in the nature of the target and the type of the immune re- sponse, known as the innate and adaptive immune responses, Ce lls of the innate immune system represent a first line of defense, a primitive response. Cells of the innate immune system include NK cells, CD3+ CD56+ t-eens or NK-like t-eens. and y6 T ce lls. These cells playa role in barrier defenses involving mucosal and cutaneous immu nity. They do not need to Immunological defense characterized by specificity and memory Toll like receptors Not MHCClass II restriCted Cytokines Chemokines Complement yl T - . __ T_._--. j lnnate immune system •••• First line of defense with a maJor role in banief immunity Definition B cell and liNKcell neopl asms are clonal tum ours of matu re and immature B cel ls, T ce lls or natural Killer (NK) cells at vari- ous stages of differentiation, Because NK cells are closely related . and share some immunophenotypic and functional prop- erties with T cells, these two classes of neoplasms are considered together. B-cell and T-cell neopla sms in many re- spects appear to recapitulate stages 01 normal B-cell or t-een differentiation, so tha t they can be to some extent class ified according to the corresponding normal staqe. However, some common B-cell neopl asms. e.q . hai ry celt leukaemia, do not clearly correspond to a no rmal B-cell differentiation stage. Some neoplasms may exhibit lineage heterogeneity. or 158 Introduction and overview 01the cassmcatoo 01the lymphoid neoplasms
  • Central lymphoid tissue Peripheral lymphoid tissue Precursor s-cene Peripheral (mature) B-cells Bone marrow Interfollicular area Follicular area Perifollicular area Progenitor B<e<1 Pre-Ekell Immature B-<ell «c:--8-<011 •Na... B<e<1. .... AG ExtrafotJiCular ....... ----- ---- Memory B-cells Marginal zone (@f~4 I I / / / / GC neoplasms Follicular lymphoma Burkill lymphoma OLBGC. (some) Hodgkin lymphoma Pre-GC neoplasm Mantle cell lymphoma Precursor B-cell neoplasms B lymphoblastic Ieukaemlallymphoma Post-GC neoplasms Marginal zone& MAlT lymphomas lymphoplasmacytic lymphoma cursu:DlBCl(some) Plasma cell myeloma Fig,auz Diagrammatic represenlatiooof~II diflerentiatioo and relationship tomajor ~II neooasms. ~II neocasme correspond tostagesofB-cell maturation, even ItIoogh the precise cell counterparts arenot known inall Instances. Precursor s-ceu nat mature inthebone marrow may undergo apcotose ordevelop intomature naive B-cells that, fol.. '(lw'ng e~sure toantigen and blasttransformation, may deveiop intoshOl1·lived plasma cells orent8l'thegerminal centre (GC)where somatichyp&mlulatiOn and heavy chain class switchingoccur. Centroblasts, thetransf()(ll16(j cellsof the GC, either undergoapcotcsis ordevelop into centrocytes. Post-GC cells include both klng-lived plasmacells and mem- ory/marginal zone B-cells. Most B-cellsareactivatedwithintheGC, butT-cell independent activation can take place ootsideof thegerminal centreandalsoprobablyleads tomem- ory type B-cells. Monocytoid B-cells, many of which lacksomatic hypermutatioo, are not illustrated. Dl.BCl,diffuse large Bcell'Ymphoma; CLUSll, chronic lymphocytic leukaemia/small 'Ymphocytic lymphoma; MAlT, meccsa-essccated lymphoid tissue; AG. antigen; FDC, fojlic· u1W Oeooriticceli. Red bar. irmnurKlglobulinheavy chaingene (IGH@) rearrangement;bluebar,immunoglobulinlightchaingene(IGl)rearrarJgem&nt;b1ad1 insertions intheredand blue tersindK:ite !WI'Iatic hypermutation. extratollicular maturation. Other antigen- exposed B cells rniqrate into the centre of a primary follicle, proliferate, and fiJi the follicular dendritic cell (FOG) meshwork, forming a germinal cenlre (l325A, 1355AI. Germinal centre centrobtasts express low levelsof slg. and also switch oHexpres- sionof BGL2 protein; thus. they and their progeny are susceptible to death through acootose (1828A1. Centrobtasrs express COlO and BGlS protein. a nuclear tran- scription factor that is expressed by both centroblasts and centrocytes. BCL6 is not expressed in naive B cells and is switched off in memory B cells and plasma cells 11346. 17601. In the germinal centre, somatic hyper- mutation occurs in the immunoglobulin heavy and light chain variable (IGV) region genes; these mutations may result in a non-funct ional gene. or a gene tha t produces antibody with lower or higher affinity for antigen than the native IG gene. Also in the germinal centre some cells switch from IgM to rgG or IgA pro- duction. Through these mechanisms, the germinal centre reaction gives rise to the higher aHinity IgG or 19A antibodies 01the late primary or secondary immune re- sponse 11356AI. The BCL6 gene also un- dergoes somatic mutation in the germinal cen tre, however, at a lower frequency than is seen in the IG genes l 1698A1. On- going IGVregion gene mutation with intra- clona l diversity is a hallmark of germinal cent re cells. and both IGV region gene mutation and BCL6 mutation serve as markers of cells that have been through the germinal centre. Most dilfuse large B-cell neoplasms (DLBCL) are composed 01cells that at least in part resemble can- trobtasts and that have mutated IGV Introduction and overview 01the classification of the lymphoid neoplasms 159
  • •, >90% 01 cases -:./.,>50% 01 cases -:01., <50%01 cases e:-,<l<ni. 01 cases • IRF4IMUM1, inletfeton regu- IabngIacb' 4:ANXA1, AnneXll"lAl; PC, praIileratIon celllreS: " plasma eel c:ornponent po$IllYe;', some grades 3a and 311;- , DLBCl oIgerTTlInaI centre8<eI type(GCB) elqlAlSS COlOand BCl6; " . DlBQ. 01 aclro'aIed 8<eI type (ABC) aretypically posllMt lor IRF41MUM1; "'. some Dl8Cl areC05. ; NA. not applc:able; lPl,1yrnptooo p1asmacylic lymphoma; MIL, ITIlIrgmI zone I)mphoma; MeL nlall1le eeI~ . fig.I.O] SChematic diagram showing pherlotype 0/8 ~ at~ stages of mah.ra1ion. TOT is II feature of earty Iyn1)hOid preanors,irdIclIng boIh Band TIyrrfJhobIasts. asweias!he blasts in some cases ofacu1ll myeloid leukaemia. C079Aand PAX5 appNI' allhe bme ofheavy etlanger-.e rearral'lQelTlelll. COlO isI'IOt e~ IA'ltIIIhe stage ofinIrrI.JllOgIobuIirlliljll chain gene (/GLJ I'8aITllflQE!I' TOT,Iermml ~ IransJerase; SHM,so- ma1lc~ ; Red t.,/GH@ ~ll blue bar./GL rearrarJgelTleflt; Pre-8CR. pre-8<eI receplor ~ sisIi1g 01 aIGheavy thaI'l and !he IIWfOgale io,tJl chail (YItIch is ~ d twolri;ed smaI pepIides VpreB llf'Id 45,represenled in~J; BCR.BcelIl'llOfII*;Irol rnetln 8 eels:Redbarandblue barwiItl bladti'lser1DJs,fNIfIIIglId IGH@ andIGl. QeIleS WIth somabch~. genes, consistent with a derivation from cells that have been exposed to the qe - minal centre. Burkitt lymphoma cells are BCL6+ and have mutated IGH genes, and are Ihus also thoughl to correspond to a germinal cen tre blast celt. Both Burkitt and DLBCL correspond 10 prolfer- ating cells. and are clinically aggressr.oe n nnours. Centrobrasts mature to centrocstes. and these cene are seen predomina ntly inthe light zone of the germinal cen tre. Centro- cvtes express slg that has an altered an- tibody combining site as compared WIth that 01 their oroqenrtors. based both on somatic mutations and heavy chain class Switching Centrocytes with mutations thai result in increased affinity are rescued from eocotose and they re-express Bel2 protein 11355A1.Throug h inleraction"";tn surface molecules on FDC 's and t-cees. such as CD23 and CD40 ligancL centro- cytes swilch off BCL6 protein expression 1346, 17601. and oitterennate into either memory B-eetts Of plasma cens 1t355AJ. BCL6 and IAF4/M UM 1 are reciprocally expressed , with IAF4/MUM l being posi- tive in late cernrocytes and plasma cells 166 1. t 9t4AI. IRF4/MUM 1 plays a critical role in down-regulating BCL6 expresser 11914AI, Follicular lymphomas are 1lJTlCU'S of germinal centre B-cetts (centrocytes and centrobiasts) in wh ich the germinal centre celts fail 10 undergo apcorosts. in most cases due to a chromosomal re- arrangement. t{14:18), that prevents the normal switching off 01 BCL2 proten expression, Centrccvtes usua lly preoon- inate ove r cen troblasts, and these neo- plasms tend to be indolent. Post-germinal centre memory Bccells cir· culate in the PB and comprise at least some of the cens in the follicular marginal zone s of lymph nodes, spleen and mu- cosa-assoc iated lymphoid tissue (MALT). Marginal zone e-cens of this co-roan- men t typ ica lly express pan-B antigens, surface Ig M with only low level IgO and lack both COSand COlO 12064A. 2293Bl. Plasma ceus produced in the germinal centre enter the PB and home 10 the bone marrow (BM). They conran predominantlY IgG or IgA; they lac k slg and CD20, bI.C express IRF4/MUM 1, CD79a, C03B and CD 138. Both memory B-eetls and long. lived plasma cens have mutated IGV reg ion genes, bu t do not continue 10 undergo mutation. Posl-germinal centre Beene retain the ability to home to tissues in which they have undergone antigen • .,. CyeUn ANXA1 D1 ." ." . /-" (+PCI • .'~ • NA NA Antigen Dependent Gemlinal Memory B Plasma cell eeoee B (Marginal zooe) • ,. ., I,-,--~==~= NA Mature naive 8 ., Immature B = 1[ CD20 . ;. ',' slg; C05 C010 C023 CQ.t3 C0103 BCL6 IRF..... c~ MUMI ',' .;. . ;- +/.,+ Pre-8 Antigen Independent I CD79A [PAX5 P~B Neoplasm CWSLl LPl HCl MALTlymphoma • .•t, ~ IIrge . /.;. .... 01·- 8-cIlllymphoma /. Table8.01 Immuoophenotypic featuresofCO!M'!OIlmature B-<::el reooasme. f ollicubr Iym_. MCl 811ttitl -- 160 Introduction and overv-ew 01the ctess.tcauoo of the lymphoid neoplasms
  • stimulation, probably through surface in- tegrin expression, so that B-cells that arise in MALT tend to return there, while those that arise in lymph nodes will home to nodal sues and BM p03AI. Marg inal zone lymphomas of MALT. splenic . and nodal types correspond to post germinal centre, merTIOfY B cells of marginal zone type thaI derive from and proliferate specifically in extranoctal, splenic or nodal nssoes.Plasmacell myekma corespooos to a 8M homing plasma cell. T-cell lymphomas: lymphocyte differen tia· tion and function Tlymphoc ytes arise from a 8M precursor that undergoes maturation and acqui sition of function in the thymus gland . Antig en specific T cells mature in the thymic cortex, Tcells recognizing selt-peptides are elimi- nated via a process med iated by cortical epithelial cells and thymic nurse cells. Cortical thymocytes have an immalu re j-ceu phenotype . and express termina l deoxynucleolidyl transferase (TOTl. CO la. COO. CDS, and COl. CD3 is lirst expressed in !he cytoplasm, prior 10 complete t-een receptor gene re- arrangement and export to the ce ll mem- brane. Cortical thymocytes are initially double-negative lor both CD4 and CDS. These antigens are co-expressed in rna- luring mvmocytes.and later more mature T-cells express only CD4 or CDS. These varying stages 01 j-ceu maturation are reflected in T lymphoblastic leukaemia! lymp homa (T-ALULBL). Med ullary thymocyt es have a phenotype similar to that of mature t-eensof the peri- phera l lymphoid orga ns, There are two classes of t-eens:o.~ t-eens and ~ T-cells 12841. This distinct ion is based on the structu re of the t-een receptor. The0.1 and "}'IS chains are each composed 01a vari- able (V) and constant (C) portion. They both are associated with the CD3 com- plex. which contains 't- 0 and t chains. NK-cells dO not have a complete 'r-cen receptor com plex, activated NK cells express the t and l; chains of COO in the cytoplasm. They express C02. COl , and sometimes CDS. but not surface COO. They also typically express CD16 , CD56, and variably COSl and contain cytoplas- mic cytotoxic granule proteins . NK-cells kill their targets. through antibody de- pendent cytotoxicity (ADCC) or a second mechanism involving killer activating receptors and killer inhibitory receptors ,(KIRs). As NK-cells do not rearrange the T-cell receptor genes, analysis of clonality in NK-cell prol iferations can utilise anti- bod ies to the various KIR receptors, Central lymphoid tissue Peripheral lymphoid tissue Precursor T-cene Peri heral mature T- and NK-cells FDC Skin ""WT c;ell T-binI ,.." ~~f ~,-,------+-------?~ffl' AG ®L~ZT~' .... ...,...,. Bone ryi.i;;~:" Thymus Follicle T tvmphoblastic Iymphomaneukaemia Peripheral (mature) T-cell and NK-cell tymphomaslleukaemlas Fig. ' .0<& Diagrammatic representationd T-cel drflerenbabal. T-<.:eI neopIastnscorrespondlCI dJflerent stages 01 mabntion. Lymphoid progenilClfs enteree thymus wherePfflCU'- sorT-cees deYeIopintovaried typeS 01 naiveT-ceis. The~ rnauationaI palhd naturalkiIer cells andy6 T<.efls isnot filly ~tood. Thea~ T<:eIsleave1he1l'Iyrrus where .p)n expl)Sl.Q 10 anligen they mayUI'ld9rgo b1asllranslormabon anddevelopfurtherintoC04+andCD8+ elledorandmemory T<ets,Tregulalory eelsen 1hemajortype 01 COol· eIIector T<ells.AnoIhllf speciIic type 01 eIJedor T<eIls istheIoIliculaf helperT-eel thatis found in gernjnal centres. Upon anligetjcstimulabal, T-celteSj)(Ilses may OCW" irJd&. pendenl ollhe gemWoal ceoue. or in1hecontext 01 agerminal centre reaction. FDC.Folliculardendritic cells:AG.antiQen. Introduction and overview of the classifica tion of the lymphoid neoplasms 161
  • TOT I I~T~-ce=':Iym=P:h:"':":':bc=lou:k:.:om=_===m:':(:T-Al=:lIl:B:l~) IIPeripheral T-eell lymphomas Fig.8.05 Schematicdiagram of T-<:ell maturation illustrating changes inantigenic expression. Tccell receptor (TCR) genes(TRA@, TRB@,TRG@,TRD@) areshown schematicallywithsolid red bars indicating absence ofrearrange- ment,and rearrangement ofrelevant TCR genesas additional black segments.The TRG@generearranges first, fol- lowed byTRB@ and TRD@. up T cells delete the TRD@ gene during TRA@ gene rearrangement, as TRD@is contained within the TRA@ locuson14q11.2. HOIVevef,yO Tcellsmayhaverearranged TRB@genes,withoutassembly ofacompleteup TCR Productive rearrangement gives rise totwomainT-<:ell populations.ul3and yO. wiltlexpres- sion ofltlerelevantTCR complex on the cellmembrane (shown as doubleredbars). Toll-like receptors playa role in ce ll-cell interactions and signaling. They playa critical role in the recog nition of infectious agents, initiating signaling through NFKB. While they function most prominently in in- nate immune responses, they also have a role in the adaptive immune system [1282AI· The lymphomas of the innate immune system are predominantly extranocal in presentation, mirroring the distribution of the functional components of this system. It is interesting that many t-een and NK-ceil lymp homas observed commonly in the paediatric and youn g adult age group are de rived from cells of the innate immune system {10351. These include ag- gressive NK -cell leukaemia, systemic EBV-positive t-een lymphoproliferative disease (LPD) of ch ildhood. most heoato- splenic t-een lymp homas, and y8 Teen lymphomas affectin g cutaneous and mucosal sites. Anaplastic large cel l lym- phoma (ALC L) is the most common pae- diatric T-cell lymphoma, and also is of cytotoxic origin. However its normal cellular counte rpart, if one exists, is unknown. y8 t-eens express neither CD4 nor COB, and also usually lack CDS. A subpopulation expresses COB. They comprise less than t-een subsets, Granzvme M is expressed in bepatosorenrc T-cell lymp homas, cuta- neous .,8 t-een lymphomas, and most intestinal t-eenlymphomas tested, linking these neoplasms to the innate immune system 11 1911. T-cells of the adaptive immune system are heterogeneous and functionally comp lex, and include naive. effector (regulatory and cytoto xic) , and memory t-eens. Inter- esting ly, t-een lymphomas of the adaptive immune system present primarily in adults, and are mainly nodal in origin, contrasting with the extranodal r-cenfym. phomas of the innate immune system /10351. CD4-positive T-cells are primarily regulatory, acting via cytokine production CD4-positive cells are divided into two maj or types, based on their cytokine secretion profiles, known as Th1, and Th2. Th1 cells secrete inter leuk in {IL)-2 and interferon t , bu t not IL·4. 5, or 6. In con- traer, Th2 ce lls secrete IL·4, 5, 6, and 10 12841, Th 1 cel ls provide help mainly to other t-eens and macropbaoes. whereas Th2 ce lls provide help mainly to Bcens. in the production of antibodies /2851. CD4-positive T-cells can act to both help and suppress immune responses, and consist of multiple sub populations only rece ntly recognized. Recen tly much has been learned abouta unique CD 4+ t-een subset found in the normal germinal centre. These cells, termed follicular T-helper cells (TFH), pro- vide help to B-cells in the co ntext of the ge rminal centre reaction j631, 852. 1656Al. They have a unique phenotype. expressing the germinal centre-associated markers BCL6 and COlO, normally found on a-cens. TFH exp ress CD4, CDS? PD· 1, and produce the chernckine CXCL13 and its rece ptor CXCR5, CXCL 13 causes ind uction and proliferation of FOe; CXCL 13 also facili tates the migration of8 and T cel ls expressing CXCR5 into the germinal cen tre. Recent studies have identified increased expression of CXCL13 in angioimmuno blastic T-cell lymphoma {AITL}, a finding that helps to link together many of its clinical and pathological tea- tures 1631, 852. 1656Al. Notably AITL is associ ated with polyclonal hyperpamma. glo bulinaemia and expansion and prolif· eration of both B-cells and CD2 1+ FDC's within the lymph node. A CD4+ T cell with very different properties is the regulatory T cell (Trag), which fuoc- trons to shut off and sup press immune responses 12043Aj. This cell is thoug htto 5% of all normal r-ceus.and show a re- stricte d d istribution, being found mai nly in the splenic red pulp, intestinal ep ithelium, and other epithelial sites. It is notable that these sites are more com monly affected by yo T-cell lymphomas, which otherwise are relatively rare 147, 241, 1303j. yO T-cells have a restricted range of antigen recog- nition, and represent a first line of defense against bacterial oeotroes, such as heat shock proteins l2841. They areoften involved in responses to mycobacterial infections, and in mucosal immunity More rece ntly, the pattern of cytolytic mol- ecules has been investigated and corre- lated with both cellular origin and funct ion. For example, to date five granzymes have been demonstrated in human cells j 1984Aj. These enzymes are similar in struct ure, but differ in their sub- strate specificity and chromosomalloca- nons. Granzyme M, a nove l member of this family, has unusual enzyme speci- ficity, preferring clea vage after meth ionine, leuci ne or norleuc ine. It has been sug- gested that this enzyme may playa role in the effector phase of innate immune re- sponses. Its expre ssion is rest ricted to NK-cells, CD3+ CD56+ t-eens. and yo J-ceus, bu t it is absent in other cytotoxic I Cytoplasmic Surface I CD4 + IDouble + CD8+ Ml:tdullary 88~~e~" C0 3 (3 CD1a CD4/CD8 CD2ICDS 162 Introduction and overview of the classification of the lymphoid neoplasms
  • Table a.o2 Imm~typic features01 common manse T-cell arid NKoCeII reooasrns. Neoplasm. CD) CD4 CDS CD7 COS C02 TlA1 GrB CDJO CD2S C056 C016 COS7 BCl6 COlO EaV EMA PM teu T.lGl Ani. Ao'l" ENKIT, Maul typt EATL HSTL SPTCl "ISS Pmry cutMllOU• .,6 T"", _ AITl AlCl,ALK+ AlCl,AlK· • • • ., ., • • • ." • • • • • • • • .,- .,- .,- .,- • .,- • <• • • • • • • • .,- .,- • ,'- .,- • • • • • • • • • • • • • .,- .,- • • • • • • • • .,- • • • • • • -. , .,- • -,. .. .. •• • .. .. • • <., • • • .,- ., • • -' -' • .,- -' • • -- .. • c,cytopla~ C03(01)'. restricled toC03&: " T<eII receptor 'l'6: 'IIi, a rJIfIOriIy ofcases expresses the o;fI T-ceHreceptor. " cose isexprMSed inIha moIlO1'lOI"phic t)1Itt of EAR 0( Type II: " , EBVis Ibsenl in neoplastic cess. but isnearly always present inasubpopuIabon ofbackgrourld 8-ceIs; . ,PTCl. OOS is 001 a Slrge disease,buI ahet- trOgenttOUS group,andItlefelore, avanety ofimml.flOPhenotypic proftles canbe seen. A, a subset of PTC,l. NOS Ire0&riVed !rom loIicuIar helperT-eels rrFH), and often ex- press CDS7, COlO and BCl6: T·PLl , T~ proIymphocytic leukaemia; T-LGl, T<eIIlarge gra1u!af lymphocyllC leukaemla; ATLl, adiJft T-<;8" leukaemia/lymphoma: AggNK, aggressive NK-cel leukaemia, ENKIT-nasaltype. MranodalNKfr-telllymphoma, nasa~lype; EATL, enteropathy-associated T-eelIlymphoma; HSTl. hepatosplenic T-ceH lyrr¢loma: SPTCL, subcutanlC!JS panl'licu~tis-li ke T-een Iymptloma; MFISS, mycosis tungoides and sezary syndrome: primary cutaneous COJO+ lPD, primary cutaneous CD30+ T-<;elI lymphoproll!erativedisease, including primary cutaneousanaplasticT-cell lymphoma:AlLY. ang'oimmunoblestic T-ce~ lymphoma: PTLC, NOS, periphlfa! T-cell lymphomas, nototherwise specified: ALCL, anaplastic large cel lymphoma. 00,granzyme B;Per,perforin, play an important role in preven ting au- toimmunity. Tregs express high den sity CD25, and the tran scription factor FOXP3, in combination with C04, Adult T-cell leukaemia/lymphoma (ATLL), has been linked to Treg ce lls based on ex- pression of both C025 and FoxP3, and this finding helps to explain the marked mmunosuppression associated with ATLL 11862A1· Recent studies have tried to relate the pathological or clinical manifestations of t-een lymphomas to cvtokme or onemo- kineexpression by the neoplastic cells, or accompanying accessory cells within the lymph node. For example. the hyper- calcemia assoc iated with ATLL has been linked to sec retion of factors with osteo- Clast-activating activity 1664, 13581. The haemophagocytic syndrome seen in scme T-cell and NK-celt malignancies has been associated wit h sec retion of both cyto- kines and chernokmes . in the selting defective cytolytic function (737, 12761. Genetics Several mature B-cell neoplasms have characteristic genetic abnormalities that are important in determining their biologic features and can be useful in differential diagnosis. These include the t(11:14) in mantle cetl lymphoma, t(14:18) in follicular lymphoma, 1(8:14) and variants in Burkttt Iymphana, and 1(11:18) in MALT lymphoma 1515,1 104, 12851. The 1(11;14) is seen in both mantle cell lymphoma and a fraction of cases of plasma cell myeloma, but minor differences in the tra nslocation exist , involving different portions of the irnrronoglobulin heavy chain gene (IGHO) (1991. The most common paradigm tor trans locations involving the IGHtlon 14q, is that a cellular proto-oncogene comes under the influence of the IGH@promoter For example, in follicular lymphoma. the overexpreeeton of BCL2 blocks apoptosrs in germinal centre Bccells. The t(11;18), common in MALT lymphoma, results in a fusion gene , AP/2/MALTI 1574, 1837, 2 109AI. The expression of API2 inhibits the activity of several caspases. The part- ner gene, MALTI, activates the NF",B pathway, as do other nensrocatons found in MALT lymphoma, such as t(1;14) and t(14 :18). Only a few T-cell neoplasms have thus far been associated With specific genetic abnormali ties. Anaplastic large cell lym- phoma, AU<+, is defined by trensocercos involving the ALK (anaplastic lymphoma kinase) gene on chromosome 5, (t(2;5) and variants 1582.12291). Hepatosoieoc r-cea lymphoma is associated with Introduction and overview of the classification of the lymphoid neoplasms 163
  • l)rnphoplasmacylic 1.4% • Diffuse large B-cell 37% Fig. 8.06 Relative frequencies ofB-celilymphoma subtypes in adults. Significant differences exist in different geo- graphicregions. However, dilluse large B-eelilymphoma(OlBCl) and~ I icular lymphomaarethe most common sub- types irrespectiveofgeographicor ethnicgroup.Note thatthese figures unoerasmate theincidence of CLUSLl, as only patients presenting clinically with lymphoma were included, MCl, mantle0011 lymphoma; ClUSlL, chronic lym- phocytic Ieukaemialsmalilymphocytic lymphoma; PMLBCl , primary mediaslinal large B-celilymphoma; SMZl, splenic marginal zone lymphoma; NMZL, nodal marginal zooe lymphoma.Oala based on{51}. but also can be seen rarely in mature lym- phomas l451A, 675A, 88DAI. Genetic features are playing an increas- ingly important role in the classification of lymphoid malignancies,and formanyofth:l small 8-celllymphomas and leukaemias, recurren t genetic alterations have been identified. However, the molecular patho- genes is of most T-cell and NK-ceillym- phomas remains unknown,Genetic studies, in particular PCR stud ies of IGH@and Teen receptor (TCR) gene rearrange- ments and fluorescence insituhybridization (FISH), are valuable diagnostic tools,both for determination of clonantv in 8-cell and T-cell proliferations (aiding in the ditteren. tial diagnosis with reactive hyperplasia), and in identifying translocations associ- ated with some disease entities, The WHO classification emphasizes the importance of knowledge of clinical lea- teres, both for accu rate diagnosis, aswell as for the definition of some diseases, such as margina l zone lymphoma of MALT type versus noda l or splenic mar- ginal zone lymphoma, mediastinal large B-celilymphoma versus DLBCL,and roost mature T-cell and NK-cell neoplasms. Diagnosis of lymphoid neoplasms should not take place in a vacuum , but in the context of a complete clinical btstorv Lymphoid malignancies range in their clinical behaviour from low grade to high grade, However, within anyone entity a range in clinical behaviour can be seen Moreover, histological or clinical proqres- sian is often encountered during a pa- tient's clinical course. For these reasons, the WHO class ification does not attempt to stratify lymphoid malignancies in terms of grade. Both morphology and immune- phenotype often change over time, asthe lymphoid neoplasm undergoes clonal evolution with the ecqutstion of additional genetic changes, In addition, evolution over time does not necessarily lead tothe development of a more aggress ive lym- phoma, For example, patients with DLBCL can relapse with a more indolent clonaity related follicular lymphoma, Someof these clonal evolutions can be unexpected and not obviously connected, such as thede- velopment of a plasmacytoma in a patient with CHl [1042B). Traditionally,classical Hodgkin lymphomas (CHL) have been considered separately from so-called "non-Hodgkin lymphomas' However, with the recognition that CHL is of B-cell lineage, greater overlap has been app reciated between CHL and WII...T l)rnp homa 9% ManUe celll)rnphoma 7% • Follicular 29% • High Grade B. NOS 2.5% • Nodal marginal zone 2% • Splenic marginal zone 0.9% • Primarymed large B-cell 3"A: • Burkitt 0.8% .CLLlSLL 12% immunophenotypic profiles that are very helpful in diagnosis. However, immune profiling is somewhat less helpful in the subclassification of T-cell lymphomas. In addition, while certain antigens are commonly associated with specific dis- ease entities, these associations are not entirely disease-specific. For example, CD30 is a universal feature of ALCL, but can be expressed in other T-cell and B-cell lymphomas and classical Hodgkin lym- phoma (CHL), Similarly, while CD56 is a characteristic feature of nasal NKff-cell lymphoma, it can be seen in other T-cell lymphomas, and in plasma cell neoplasms 1208,701,13251. Within a given disease entity, variation in immunophenotypic fea- tures can be seen For example, most hepatosplenic 'teen lymphomas are of yi5 't-een phenotype, but some cases are of aj3 derivation. Likewise, some follicular lymphomas are CD1Q-negative. Addition- ally,the presence of an aberrant immuno- phenotype may suggest or help to confirm a diagnosis of malignancy (10341, While lineage is a defining feature of most lymp hoid malignancies, in recent years there has been a greater appreciation of lineage plasticity within the haematopoietic system, Lineage switch, or demonstration of mUltiple lineages is most often encountered in immature haematolymphoid neoplasms, Principles of classification The classification of lymp hoid neoplasms is based on utilisation of all available in- formation to define disease entities 1898l. Morphology and immunophenotype are sufficient forthe diagnosis of most lymphoid neoplasms. However, no one antigenic marker is specific for any neoplasm, and a combination of morphologic features and a pane l of antigenic markers are necessary for correct diagnosis, Most B-cell lymphomas have characteristic isochromosome 7q. However, the molec- ular pathogenesis of most other T-cell and NK-cell neoplasms remains to be defined, Multiple other genetic tools have been broug ht to bear on the study of mature lymphoid neoplasms, These include com- parative genomic hybridisation (CGH) , and the newer and more sensitive tech- nique of array CGH, both of which can identify areas of deletion or amp lification within the genome 165-167}. Gene expression microarrays can interrogate the expression of thousands of genes at the RNA level, helping to elucidate path- ways of activation and transformation 1509, 510,513,701, 1507, 1867, 1944}. Most recently, studies have begun to explore changes at the epigenetic level that control the expression of multiple genes {13141. 164 lntroduction and overview of the class ification of the lymphoid neoplasms
  • C P fim ary Cu!arlIIOUll Ala. 1.7% c l.lnctall s<table PTCl 2.,5% c AduI T..::eI leukemlatlylT1jlhomll 9 no . Al'IalUslic I8fge cell lymphoma. Al K. e n. . Anaplastic '-lie cel lym~ AlK. 55", allograft rejection or graft versus host dis- ease (GVHD) and primary immune defi- cienc ies. Some autoimmune diseases are also assoc iated with an increased risk of lymphoma, particu larly B-ce illymphomas in patients with lympboepithelial sraraoen- tis or Hashimoto thyroiditis 11114, 11161. Mutations in genes con trolling lympho- cyte epoptosfs have been linked to a risk for both autoimmune disease and lym- phoma (mainly B-cell types). Patients with the autoimmune Iymp hoproliferative syn- drome. which usua lly is caused by ge rmline mutations in FAS, have an in- creased risk for a-cer lymphomas and Hodgkin lymphomas 12108). Somatica lly acquired FAS gene mutations also have been reported in some spo rad ic B-cell lymphomas, most co mmonly marginal zone lymphomas 1855). Recent stud ies employing molecula r epidemiology have identified polymorphisms in a number of immunoregulatory genes that appear to impact both risk of lymphoma and prog- nosis within a patient cohort l359A. 1248A, 2358C). Molecular epidemiology is a relatively recent area of investigation and more data will be accumulated in the com ing yea rs. For example, a recent study found incre ased risk associated with polymorphisms in certain drug metabol izing enzymes 116A}. Mature T-cell and NK-ceil neoplasms are fig. 8.07 Relative frequenciesofmature T<elllymphoma subtypesinanadultpatientpopulation. Significant differences exist indifferent geographic regions.However.peripheralT<elllymphorna.nototherwise specified (NOS)and AITL are two ofthemost common subtypes intemationally.' Notethatlhe category ofenteropathy-type T<elilymhpoma (Erel )' used inthisstudy was noteqllivalent toenteropathy-associatoo T<eII ~ (EATL)asdeflood in this monograph. ErCL was utilized largely asageneric category lormost T<ell lymphomas ifl'/Ol'ving theintestine.inclusive of EATLand)'0T-<:elI lymphomas. Data courtesyofJ. Vase and TheInternational PeripheralT-CellLymphoma Project (57A). lymphoma has a med ian age of -35 years. Of the mature B-cel l lymphomas, only Burkitllymphoma and DLBCL occur with any significant frequen cy in chi ldren . Most types have a male predo minance (52-55%), but mantle cel l lymphoma has a striking male predo minance (74%) , while fema les predom inate in follicular lymphoma (58%) and most particularly in primary mediastinal large B-ce ll lym- phoma (66%). Primary med iastinal large B-cell lymphoma and classical Hodgkin lymphoma of the nodular sclerosis subtype have similar cl inical profiles at presenta- tion, most commonly affecting adolescent and young adult females. These common clinical features first prompted consrcera- tton that these lymphomas might be re- lated 11870, 1944, 2265) One majo r known risk factor for mature B-ce ll neoplasia appea rs to be an abnor- mal ity of the immune system, eithe r im- munod eficiency or autoimmune disease. Although evidence of immune system ab- norma lities are lacking in most patients with mature B-cell neop lasms, immunod- eficie nt patients have a markedl y in- crease d inc idence of a-cen neoplasia, partic ularly DLBCL and Burkitt lymphoma (193,331. 1569}. Major forms of immuno- deficiency currently include infection with the human immunodeficiency virus (HIV), iatrogenic immunosuppression to prevent Epidemiology Precursor lymphoid neoplasms including B lymphob lastic leukaemia/ lymphoma (B-ALL.JLBL) and T fyrnphoblastic leukaemia! lymphoma (T·A LLJLBL) are primarily dis- easesof children. 75% of cases occur in children unde r six years of age Ap oroxr- mately 85% of cases presenting as ALL areof precursor B-ce ll type. whereas lym- phoblastic malignancies of precursor T-cell type more often present as lym- phoma, with med iastinal masses. A male predominance is seen in lymphob lastic malignancies of both B-cell and T-cell lineages. Mature s-een neoplasms comprise over 90% of lymphoid neoplasms worldwide 151, 791. They represent approximately 4% of new cancers each year. They are more common in develop ed countries, particularly the United States. Australia, New Zealand and Western Europe. The most recent survey from the Survei llance, Epidemiology and End Results (SEER) program in the United States indicated an incidence rate per 100 000 per sons per yearof 33.65 for all lymphoid neop lasms, 26.13 for a-ce.r neoprasms. 1.79 for all T- cell neoplas ms, and 2.67 for Hodgkin lymphoma 11525A). The most co mmon types are follicular lymphoma and DLBCL, which tog ether mak e up more than 60% 01 all lymphomas excl usive of Hodgkin lymphoma and plasma cell myeloma 137, 511. The incidence of lym- phomas. in partic ular Been lymph omas, is increasing worldwide, with more than 280000 cases occurring ann ually each year 121 12A). The individual a-cen neo- plasms vary in their relative frequenc y in different parts of the world. Follicular lym- phoma is more common in the United Slates (35% of non-Hodgkin lymp homas) and Western Europe, and is uncommon in SouthAmerica, Eastern Europe, Africa and Asia. Burkitt lymphoma is ende mic in equatorial Africa, where it is the most common childhood mal ignancy. but it comprises only 1-2% of lymphomas in the United States and Western Europe. The median age for all types of mature B- cell neoplas ms is in the 6th and 7th decades, but med iastinal large B-c ell many forms Qf Been malignancy. The 4th edition of the WHO classification reco g- nizes these grey zones, and provides for the recog nition of cases that bridg e the gap between these various forms of lym- phoma 12265). Introduction and overv iew of the classification of the lymphoid neoplasms 165
  • relatively uccorrmon. In a large interna- tional study that evaluated lymphoma cases from the United States, Europe, Asia and South Africa, T-cell and NK-cell neoplasms acco unted for only 12% of all non-Hodgkin lymphomas [51}, The most common subtypes of mature t-een lym- phomas are peripheral r-eef lymphoma, not otherwise specified (NOS) (25.9%) and angioimmunoblastic T-cell lymphoma (AITL) (18.5%), respectively (57A}. T-cell and NK-cell lymphomas show sig- nificant variations in incidence in different geographical regions and racial popula- tions In gene ral, "l-cell lymphomas are more common in Asia [6161. These differ- ences result from both a true increased in- cidence, as well as a relative decrease in the frequency of many B-cell lymphomas, such as follicular lymphoma. One of the main risk factors for T-cell lymphoma in Japan is the virus, HTLV-1. In endem ic regions of southwestern Japan, the sero- prevalence of HTLV-1 is 8-10%. The cu- mulative life-time risk for the development of adult r-cenieokaemlaavrrctoma (ATLL) is 69%"for a seropositive male and 2.9% fora seropositivefemale [6831. Other regions with a relatively high seropreveience for HTLV-1include the Caribbean basin.where Blacks are primarily affected over other racial groups {760f. Differences in viral strain also may affect the incidence of the disease [523,13451. Another major factor influencing the inci- dence of r-cea and NK-ceil lymphomas is racial predisposition. EBV-associated NK and T-cell neoplasms. including extran- odal NKfT-cell lymphoma, nasal type, ag- gressive NK leukaemia, and paediatric EBV+ T-cell and NK-cell lymphomas are much more common in Asians than they are in other races {2n In Hong Kong, nasal NKfT-cell lymphoma is one of the more common subtypes, accounting for 8% of cases By contrast, in Europe and North America , it acco unts for less than 1% of all lymphomas. Other populations at increased risk for this disease are indi- viduals of Native American descent in Central and South America , and Mexico {40,3411. who are geneticall y related to Asians [8921. Finally, enteropathy-associ- ated J-ce!l lymphoma is most common in individualsof Welsh and Irishdescent, who share HLA haptotvpee that confer an increased risk of gliadin allergy and sus- ceptibility to gluten-sensitive enteropathy 154S}. 10 PTCL occu r with increased frequency in the setting of immune supp ression, especially following organ transplanta- tion, a finding that is not well understood {758A, 1582Al The comb ination of two factors, both immunosuppression and chronic antigenic stimulation. appear to increase risk. Hepatosptenic T-cell lym- phomas are most common, but primary cutaneous and mucosa-assoc iated T-cell lymphomas have been reported as well {3311. Recent data from the SEER pro- gram indicate a modest increase in the incidence of t-ceu neoplasms in the United States to 2.6 cases per 100000 persons per year, with the greatest increase occu ring in the category of cutaneous T-eeillymphoma (492A, 1525A). Etiology Infectious agents have been shown to contribute to the development of several types of mature B-cell, T-cell and NK-cell lymphomas. Epstein-Barr virus (EBV) is present in nearly 100%of endemic Burkitt lymphoma and in 15- 35% of sporad ic and Hrv-assocrateo cases {877, 1780Al. and it is involved in the pathogenesis of many B-eelilymphomas arising in immuno- suppressed or elderly patients, including many post-transplant Iymphoproliferative disorders, plasmablastic lymphoma and EBV+ large B-ceillymphoma of the eld- erly. EBV is also associated with extra- nodal NKfT-cell lymphoma and two paediatric t-een lymphomas. systemic EBV+ t-eenLPD of childhood and hydroa- vaccin iforme-like t-een lymphoma. The exact cause of these EBV+ T-cell lym- phomas of childhood is not clear. Risk factors may be either high viral load at presentation, or a defective immune re- sponse to the infection {179n Chronic active EBV infection may precede the development of some EBV+ t-een lym- phomas {1094, 1797f.In casesassociated with chronic EBV infection, a polyclonal process may be seen early in the course, with progression to monoclonal EBV+ T-cell lymphoma 11094}. Human herpesvirus-8 (HHV8) is found in primary effusion lymphoma and the lym- phomas associated with multicentric Castleman disease, mainly seen in HIV- infected patients {372). It is of interest that the same virus causes a number of B-cell Iymphoproliferative disorders which differ in their clinical manifestations {617A). Human T-ceil lymphoma/leukaemia virus type 1 (HTLV1) is the causative agent of adult T-cell lymphoma/leukaemia, and is clona lly integrated into the genome of transformed T-cells !2148). In this condi- tion as in HHV8-associated disorders, a spectrum of clinical behaviours are seen, although most cases of ATLLare aggres- sive. Hepatitis C virus has been implicated in some cases of Iymphoplasmacytic lym- phoma associated with type II cryoglobu- linaemia. splenicmarginalzone lymphoma, nodal marginal zone lymphoma and DLBCL 112A, 88A, 527A, 534A, 1073A, 1434, 1775A, 2506), The role of the virus in tumour initiation is not clear. However, it does not directly infect neoplastic a-cens. and appears to influence lymphoma development through activation of a B-cell immune response. Bacteria, or at least immune responses to bacterial antigens, have also been impli- cated in the pathogenesis of MALT lym- phoma. These include H. pylori in gastric MALT lymphoma (998, 1587,2444,2445), B. Burgdorferi in cutaneous MALT lym- phoma in Europe {192), Chlamydia psittaci.C. pneumoniaeand C.trachomatis in ocula r adnexal MALT lymphomas in some geographic areas {394, 18981and Campylobacter jejuni in intestinal MALT lymphoma associated with alpha heavy chain disease {1781, 1812f Environmental exposures also have been linked to a risk of developing B-ceil lym- phoma. Epidemiolog ical studies have implicated herbicide and pesticide usein the development of follicular lymphoma and DLBCL !460A, 903A). Exposure to hair dyes had been identified as a risk factor in some older studies, but newer dye formations have removed potential carcinogens {2496AI. Conclusion The multiparameter approach to classifi- cation adopted by the WHO classification has been validated in international stud- ies as being highly reproducible, and en- hancing the interpretation of clinical and translational studies. In addition, accurate and precise classification of diseaseenti- ties facilitates the discovery of the molec- ular basis of lymphoid neoplasms in the basic science laboratory151, 1034, 1525A1. I I ~ • iI Il I• =• • • ••• 166 Introduction and overview of the classification of the lymphoid neoplasms
  • B lymphoblastic leukaemia/lymphoma, not otherwise specified M.J, Borowitz J,K,C. Chan Definition B lymphoblastic leukaemia/lymphoblastic lymphoma is a neoplasm of precursor cells (lymphoblasts) corrmined to the Bcea lineage. typically composed of small to medium-sized blast cells with scant cyto- plasm. moderatelycondensed todispersed chromatin and inconspicuous nucleoli, involVing bone marrow (BM) and blood (8 acute lymphoblastic leukaemia/ALL) and occasionally presenting with primary involvement 01 nodal or extranodal sites (B lymphoblastIC IymphomallBl), By coo- venton. the term tymphcma is used when the process is confined 10a mass lesion with noor minimal evidence of peripheral blood (PB) and 8M involvement. With ex- tensive 8M and PB involvement, lym pho- blastic leukaemia is the appropriate term . If the patient presents with a mass lesion and Iymphob lasts in the 8M. the distinc- tion between leukaemia and lymphoma is arbitrary 11 5501. For many treatment pro- tocols, a figure of 25% BM blasts is used as the threshold for defining leukaemia . In contrast to myeloid Ieokaemtas. there is no ag reed-upon lower limit for the percentage of blasts required to establish a diagnosis of lymphoblastic leukaemtas In general, the diagnosis should be avo ide d when there are fewer than 20% blasts, Presentations with low blast counts can occur but are uncomm on; currently there is no compelling evidence that failure to treat a pat ient when there are fewer than 20% 8M Iymphob lasts has an adverse effect on outcome, The term B-ALL shoul d not be used to indicate Burkitlleukaemia/lymphoma, in spite of its historical assoc iation with that lesion, Cases of B·ALU LBL with recu rrent genetic abnormalities are considered separately below ICD-O code The provisional code proposed for the fourth edition of ICO-O is 981 113 Epidemiology Acute lymphoblastic leukaemia (ALL) is primarily a d isease of children; 75% of cases occur in children under six years of 168 Precursor lymphoid neoplasms age. The worldwi de incidence is estimated at 1- 4.75/100 000 persons per year {18271. The estimated number of new cases in the United States in 2000 is approximate ly 3200, with approximately 80-85% being of precursor B-cell pheno- type {1845, 20391. B-lBL constitutes -10% 01lymphoblastic lymphomas. and the rema inder are of "T lineage 12421· Approximately 64% 0198 cases reported in a literature review were less than 18yearsofage 113671. One report indicated a male predominance {13101. Etiology Some transiccenons associated with B-ALL have been detected in neonatal specimens long before the onset of leukaemia. and monozygotic twins with concordant leukaemia frequently share genetic abnormalities {832, 15t41 , sug- gesting a genetic cornponentto at least some cases. Many of these translocations appear to be primary initiating events. Sites of involvement By definition, BM is involved in all cases classified as B-AL L, and PB is usually involved. Extramed ullary involvement is frequent. with parti cular pred ilection for the central nervous system, lymph nodes, spleen. liver and testis in males. The most frequent sites of involvement in B·LBL are the skin, soft tissue, bone and lymph nodes 1202, 1310, 13671- Med iastinal masses are infrequent {202, 1367, 19281. Clinical features Most patie nts with B-ALL presen t with evidence and consequences of BM fail- ure: thrombocytopenia and/or anaemia and/or neutropenia, The leukocyte count may be decreased , normal or markedly elevated, Lymphadenopathy,hepatcmegaly and splenomegaly are frequent. Bone pain and arIt1ralgias may be prominent. Pa- tients with B-LB L without leukaemia are usually asymptomatic, and most have lim- ited stage disease. Head and neck pre- sentations are particularly common, especially in children. Marrow and PB in- volvement may be present. but the Fig. 9.01 B lymphoblastic leukaemia, Bone rnarJOll smear. A 5everal ~asls with a highIIlIdearIc't lopiasmicratiO andvariably conoensednudear dWl). mallO, B BIymphoblasls containing numerous eo<ne azurophihc granules, percentage ollymphoblasts in the 8Mis <25% 11310,13671 . Morphology The Iymphoblasts in B-ALlA.BL in smear and imprint preparations vary from sma" blasts with scant cytoplasm, condensed nuclear chromatin and indistinct nucleoli to larger cells with moderate amounts of light blue to blue-grey cytoplasm
  • occasionally v acuolated. dispersed nu- clear chromatin and multiple variab ly oronrent nucleoli. The nuclei are round , tregUar or corwoIuted. Coarse azurophilic granules are present in some fvmoro- blasts in approximately 10% of cases. In somecases. the Iymphoblasts have a cy- toPlasmic pseudopod (hand mirror cells) In most cases the morphology of the Iym- peootasts differs from that of normal Be en precursors (haematogones) with which they may be confused. The latter typically have even highe r oucieus/cyto- plasm (N/C) ratios, more homogeneous chromatin and no discernible nucleoli, In BM biopsies. the Iymphoblasts in B-ALLare relatively uniform in appearance with round to oval, indented or convoluted nuclei. Nucleoli range from inconspicuous to prominent. The chromatin is finely dispersed The number of mitotic figures varies Lymphoblastic lymphoma is generally characterized by a di ffuse, or less comrT'lOflly, paracomcar pattern 01 involvement of lymph node or other 1JSSUe. A single-file pattern of infiltration of sot! tissues is common. Mitotic figures are usually numerous and in some cases hefemay be a focal "starry sky" pattern. The morphologiCfeatures of Band T lym- phoblastIC proliferations are inoisnn- gliShable. Cytochem~try Cy10chemistry seldom contributes to the diagnosis of ALL lymphoblasts are negative 'or nweioperoxio ase. Granules, Ifpresent, may stain light grey with Sudan Black-B staining but are less intense than myeloblasts. lymphob lasts may show PAS positivity, usua lly in the form of coarse granules. Lymphoblasts may react with non-specific esterase with a mutntocat punctate or Galg i zone pattern that shows variable inhibition with sodium fluoride . Immunopheoo<ype The Iymphoblasts in B-AlLllBl are al- most always positive for the Been markers CD 19, cytoplasmic CD79a and cyto- plasmic C022; while none of these by itself is spec ific , positivity in combination or at high intensity strongly supports the B lineage. The Iymphoblasts are pos itive for C01O, surface C022, C024, PAX5 and TdT in most cases. while C020 and C034 expression is variable: CD45 may be ab- sent. The myeloid-associated antigens C013 and CD33 may be expressed. and the presence of these myeloid markers does not exclude the diagnosis of B-ALL In tissue sections, C0 79a and PAX5 are most frequ ently used to demonstrate B-cen different iation, but the former reacts with some cases of T-ALL and is not spe- cific 19061. PAX5 is generally considered the most sensitive and specific marker for B lineage in sections 122511but it is also positive in cases 01 AML with t(8:21) and rarely in other AML 122851. Myeloperoxi- case express ion in leukaemic cells de- tected with anti-MPO antibodies excludes this d iagnosis and would ind icate either acute mye loid leukaemia or B/mye loid leukaemia. The degree of differentiation of a-uneace Iymphoblasts has clinical and genetic correlates. In the earliest stage, so called early precursor B-ALl or pro-B-ALl. the blasts express CD19, cytoplasmic C079a, cytoplasmic C022 and nuclear Tdl ln the intermediate stage. so called common ALL. the blasts express C01O. In the most mature precursor B differentiation stage, so called pre-B-ALL. the blasts express cytoplasmic ~ chains (c-u). Surface im- munoglobulin is characteristically absent although its presence does not exclude the possibility of B-AlLllBL (15841. pro- vided that other immunophenotypic tea- tures, morphology and cytog enetics are co nsistent With B-AlL. Although COl O. positivrty is seen both in B-ALl and in nor- mal haematogones. the immunophenotype of prec ursor B-ALl differs in almost all cases from that seen in normal Been pre- cu rsors, The tatter show a continuum of expression of ma rkers of 8-cell matura- tion. including surface Ig light chain. and display a reproducible pattern of acqui si- tion and loss of normal antigens {14421.ln contrast. cases of B-ALL show patterns that differ from normal with either overex- pres sion or unoerexpression of many markers including CO lO, CD45, CD38, C058 or TdT, among others 1326. 401. 1342. 23721. These crttererces can be very useful in evaluation of followup BM specimens for minimal residual disease, Genetics Antigen receptor genes Nearly all cases of B-ALL have clonal OJ rearrangements of the IGH@gene. In ad- dition, t-een receptor gene rearrange- ments may be seen in a significant proportion of cases (up to 70%) 122941so that these rearrangements are not helpful for lineage assignmen t. A •Ft;. 9.03 B~sbc lymphoma, ASkin,The ~Iic cells diffusely infiltratethe dermis -Mlh sparing oftheepidermis. BSamecase aI hp magnification shows ~ SI.mU'ldW'9 a blood vessel. 8 lyrnphobtastic leukaemiaJlymphorna. not otherwise specified 169
  • r~ 9.05 BIympIw)I:lIask leukaerria. L~ rnje. The neoplastiC eels infiIlrate cMlusely sparW1g IUmallaides .. :.•••B • •Fig. 9.04 IrIcnIased haemalcJlp'le$ A Bone marrow sedJon. B Bone marrow smear In::m anet;;rt year.Qd male. showing tympnoid eels with I high nucIeaIlcyqJlasmicratioandhcm:lgeneou$ nudear dlromaW1; nucleoli .. not observed or areindl$1lllCl These cellsresemble!he ~ inAll 01 dtilood. Cytogenetic abnormalities and onrogenes Cytogenetic abnormalities are seen in the majority 01 cases of B-AlLABl; in many cases they define specific entities with unique phenotypic and prognostic fea- tures. These cases are considered sepa- rately Additional genetic lesions that are not associated with these entities include del(6Q), del(9p). del( 12p). though mese do not have an impact on prognosis. Some genetic lesions that may be assoc iated with poor prognosis include the very rare 1(17;19); E2A·HLF ALL and the lonachromosonat amplification 01the AML 1gene on chromosome 21 (iAMP21), which accounts for about 5% of cases of All 11510]. The latter is being recognized with increasing frequency with the increased use 01 FISH studies to detect TEL·AML 1 translocations, because it can be de- tected with the same AML 1probe. Postulated normal counterpart Depending upon the specific leukaemia, B-ALL arises in either a naematopoienc stem cell or a B-ceUprogenitor. Prognosis and predictive factors B·ALL has a good prognosis in ch ildren, but it is less favourable in adults. In chil- dren, the overall complete remission rate is >95% and in adults 60-85%. Approxi- mately 80% of children with B·ALL appear to be cured, while this figure is less than 50% for adults More intensive therapy makes a difference in cure rates, and there is some evidence tor youngeradlAls at least , that therapy with more intensive "paediatric-type" regimens is associated with better outcome 1233, 8721. Inlancy. increasing age (> 10 years), higher white blood cell count, slow response to initial therapy as assessed by morphologic ex· emmanon 01P8 and/or 8M , and the pres- ence 01 minimal residual disease after therapy are all associated with adverse prognosis 1488, 679, 1976, 2023, 2093. 22951. The presence of eNS disease at diagnosis is associated with adverse out· come, and requires specific therapy 14461. The prognosis of B-LBL is also consid- ered relatively favourable. and as withB- ALL appears better in children than accns 113671. 170 Precursor lymphoid neoplasms
  • B lymphoblastic leukaemiallymphoma with recurrent genetic abnormalities MoJ. Borowitz J.K.C. Chan This group of d iseases is characterized by recurrent genetic abnormalities, in- cluding balanced translocations and abnormalities involving chromosomes, Many ch romosomal abnormalities that are non-randomly associated with B acu te tymphoblastic leukaemia (B·ALL) are not inCluded as separate entities in this sec- tal. While inclusion or exclusion 01 a ge- netic -entity- is somewhat arbitrary, those lesions that are specifically mentioned are chosen because they are associated with distinctive clin ical or phenotypic proper- tes. have important proqnosnc impliea- rcos.demonstrateomerevidence that they ale biologically distinct and are generally mutually exc lusive with other entities. BLymphoblastic leukaemiallymphoma with ~9;22)(q34;q112); BCR·ABLt Oefrlition Aneoplasm of Iyrnphoblasts corrmitted to lhe e-cen lineage in which the blasts harbour a translocation between the BCR gene on chromosome 22 and the ABL1 oncogene on chromosome 9 ICD-O code The provisional co de prop osed for the fourth edition of ICO-O is 98 12/3. Epidemiology and cl inical features Presenting features are generally similar to those of other pat ients with B-All. BCR-ABL 1 associated ("Ph . -) All is relatively more common in adults than Children, accounting for about 25% of adult All but only 2-4% of childhood All. Most children with Ph. B-All woul d be considered "high risk" by standard ageand white blood cell (WBC) features, but there are otherwise no cha racteristic docalfindings Though patients witht(9;22) B·All may have organ involvement. lym- phomatous presentations are rare _ and cytochemistry There are no unique mor phologic or cytochemical features that distinguish this from other type s of ALl. Immunophenotype B-Al l with t(9;22) is typically C01O. C019. and TdT• . There is more frequent expression of myeloid-assoc iated ann- gens C013 and C033 19851: COl17 is typically not expressed. C025 is highly associated with t(9.22) B-All, at least in adu lts 116791. Rare cases of t(9 :22) All have a T precursor phenotype. Genetics The t(9:22) results from fusion of BCR at 22q l 1.2 and the cytoplas mic tyrosine kinase gene ABL1 at 9q34. with produ c- tion ot a BCR-ABlfusion protein, In most childhood cases of All with the t(9;22), a p190 kd BCR-ABU fusion protein is produced. In ad ults, about one half of cases of ALL with the t(9.22) produce the p2 10 kd fusion protein that is present in chronic myelogenous leukaemia (CML). and the remainder prcouce the p190. No definite clinical differences have been at- tributed to these twodifferent gene prod- ucts. The t(9;22) may be associated with other genetic abnormalities, includ ing rare cases that might otherwise cause a case to be placed in one 01the other ca- tegories below, It is ge nerally considered that cl inical features in such cases are governed by the presence of the t(9:22) . Postulated normal counterpart There is some suggestion that the celt 01 origin of t(9 :22) ALL is more immature than that of othe r B-All cases 14521. Prognosis and predictive factors In both children and adults, t(9;22) All has the worst prognosis among pat ients with All. Its higher frequency in adu lt All explains in part but not completely the relatively poorer outcome of ad ults with All. In ch ildren. the presence of favourab le clinical features including age. white count and response to thera py, is associated with somewhat better outcome 1771. althoug h prognosis is still considered relatively poor. Treatment with imatinib in Fig. 9.06 Ttisbone marrow from ., iICkJIl WIth 119"22) posIbve &-ALl is ~leIy replaced by tyrnp1ctlIasb. Mitolic figl.l'eS areI'lUI'IlefOUS. addition to high-dose chemotherapy has been reported to improve early event-free survival {19751. B Lymphoblastic leukaemiallymphoma with t(v;11q23); MLL reafT8t1ged Definition A neoplasm ol lymphoblasts ccmmined to the B lineage that harbours a transloca- tion between the MLL gene at band t 1q23 and anyone 01a large number of differe nt fus ion partne rs. Patien ts with leukaemias that have deletions of 11q23 without MLL rearrangements are not in- cluded in trns group, ICD-O code The provisional code proposed for the fourth ed ition oucn-o is 981313 Etiology While the specific etiology of leukaemia with MLL transJocations is unknown. this translocation may occur in utero. with a short latency between the transloca tion and development of disease , Evidence for this includes the fact that these leukaemias are frequent in very young infants, as well as the fact that this translo- cation has been identified in neonatal blood spots of patients who subsequently develop leukaemia {7451. B lymphoblastic leukaemia/lymphoma With recurrent genetic abnormalities 171
  • Fig,9.07 B tymphoblasbc le ukaemia~ymphoma withMLLreerrarqement FISHstudy usinganMLL breekapartprobe. The normal MU gene"MLL(11q23)"appears as ajuxtaposed redand green, Of sometirnasyellow signal, The trensJo- catioo isdemonstrated byseparation oftheredandgreen probes r MLLsp")(CocrtesyofOr AJ carroll) Flg.9.08 Btymphoblasticleukaemialtymphoma with1(12;21) (p13:q22); TEUAML 1(ETV&-RUNX1)FISH study using a redprobe against RUNX1 and a green probe against ETV6. The normal genes appear as isolated redor green signals, wMe evcerce ofthefusion gene(arrows) appearsasa yelklwsignal, (CoortesyofOr.AJ carroll). ICD-O code The provisional code proposed for the fourth edition ol lCD-O is 9814/3. Genetics The MLL gene on chromosome 11Q23 has many fusion partners. The most cam- mon partner gene is AF4on cnrorosore 4q21. Other common partner genes include ENL on chromosome 19p13and AF9 on chromosome 9p22. MLL·ENL fusions are also common in T·ALL and fusions between MLL and AF9 are more typically associated with myel()d leukaemia. Leukaemias with MLL nanslo- cations are frequently associated with overexpresston of FLT-3 l801. Cases with deletions of 11q23 are not included in this group of leukaemias as they appear not to share the same clinical, phenotypic or prognostic features. proteo-qrycan neural-glial antigen 2 (NG2) is also characteristically expressed and is relatively, though not absolutely, specific. Prognosisand predictive factors Leokaerreas with the MLL·AF4 transloca- tion have a poor prognosis. Thereis some controversy as to whether reukeenee with translocationsother than the MLL-AF4 rearrangement have as poor a prcqross as trcse that do, Infants with ML1. translo- cations, particularly those <6 monfhs ~ age, have a particularly poor prognosis Definition A neoplasm of Iymphoblastscommitted to the B lineage with a translocation between the TEL (ETV6) gene on chromosome 12 with the AML 1(RUNX 1)gene on ctecrc- some 12. Epidemiology and clinical features This leukaemia is common in chiklren accounting lor about 25% of cases ~ B-ALL It is not seen in infants and decreases in frequency in older children to the point that it is rare in adulthood. Presenting features are generally similar to those of other patients with ALL B Lymphoblastic laukaemlaJlymphoma with 1(12;21)(p13;q22);TEL-AML1 (ETV6-RUNX1) cytochemical features that distinguish this from other types of ALL. In somecases of leukaemtas with MLL rearrangements it may be possible to recognize distinct lymphoblastic and monoblastic popul a- tions, which can be confirmed by immunophenotyping; such cases should be considered Blmyeloid leukaemias. Irrrnunophenotype ALL with MLL transiocanons. and most especially t(4;11) ALL typically have a CD19+, Cu tn-neqenve. CD24-negative pro-B immunophenotype, also positive for CD15l985, 16911. The Chondroitin sulfate Epidemiology and clinical features ALL with MLL rearrangements is the most common leukaemia in infants < 1 year of age. It is less common in older child ren and increases with age into adulthood. Typically patients with this leukaemia present with very high white blood cell counts, frequently>100 OClO/J-J-L. There is also a high frequency of eNS involvement at diagnosis. While organ involvement may be seen, pure lymphomatous pre- sentations are not typical. Morphology and cytochemistry There are no unique morphologic or 172 Precursor lymphoid neoplasms
  • Morphology-and cytochemistry There are no unique morphologic or cytochemical features that diSlinguish thisfrom other types of ALL. • .' .., Imrru1ophenoIyp Basts have a C019+, C010+ phenotype and are most often CD34+; other pheno- typicfeatures. including near or complete absence of COO, C020 and CD66c 1245, 533,9851.are relatively but not absolutely specific. Myeloid-associated antigens. especially CD13, are frequently expressed, but this does not indicate mixed pheno- type acute leukaemia 11551. " " " " . ~ ..• >4 • , -" " Fig.U9 Hyperdiploid ALL.G banded karyotwe stlowlng55d'll'omosomes.indudlng trisomies of4. 10 and17and kltrasomy 2t.Thefe are nostruc:llnl abnor'malitJes. (CourtesyofDr.AJ carrol). Morphology and cytochemistry There are no unique morphologic or B Lymphoblastic leukaemia! lymphoma with hyperdiploidy , f, Irrm.mophenotype Blasts are C0 19+, C01O+ . and express other markers typical of B-ALL Most cases are C0 34 + and C045 is often ab sent 19851. Patients with T-ALL with hyperdiploidy should not be considered part of this group, though most such patients have near tetrap loid karyotypes. cvtocremcet teatores that distinguish this from other types of ALL. Genet ics Hyperdiploid B-Al L contains a numerical increase in chromosomes. usually without structural abnormal ities. Extra copies of chromosomes are non random. with chromosomes 21, X, 14 and 4 being the most common and chromosomes 1. 2 and 3 being the least often seen 19151. Hyperdiploid B-AlL may be detected by standard karyotyping , FISH or flow cvto- metric DNA index 11 4011. Some cases that appear as hyperdiploid ALL by stan- dard karyotyping may in fact represent hypodiploid ALL that has undergone enooreouoncetco. doubling the number of chromosomes. Specific chromosomes that appear as trisomies may be more im- portant to prognosis than the actual number of chromosomes, with simultane- ous trisomies 014. 10 and 17 carrying the best prognosis 121231. .. .. !!' r' " ... ~ .. Definition A neoplasm of Iymphoblasts committed to the B lineage whose blasts contain >50 and usually <66 chromosomes, typically without uansiocanons or other structural alterations. There is controversy as to whether specific chromosomal additions. rather than the specific numbe r of chro- mosomes. should be part of the def inition 1894. 1806,21231. ICO-D code The provisional co de proposed for the fourth edit ion ofICD·D is 981513. Synonyms Hyperdiploid ALL; high hyperd iploid ALL: ALL with favourable trisomies. Clinical features Presenting features are generally similar to those of other patients with ALL. Epkl_ y This leukaemia is common in children , accounting for about 25% of cases of B-ALL It is not seen in infants, and decreases in freq uency in older children to the point that it is rare in adulthood. Genetics The t(12;21)(p13;q22): ETV6-RUNX1 trans- location results in the produ ction of a fusion protein that likely acts in a domi- nant negative fashion to interfere with normal function of the transcri ption factor RUNX1. This leukaemia appears to possess a unique gene expression signature 124691. The E1Y6-RUNX1 trans- lOCahon is considered to be an early lesion in leukaemogenesis, as evidenced by studies of neonatal blood spots that have shown the presence of the translo- cation Il'lchildren who develop leukaemia many years later 124001. There is evi- oeoce that the translocation is necessary butnot suHicient for the development of leukaemia 124001. Prognosis and predictive factors B-All with the TEL·AML 1 transloc ation hasa V8fY favourable prognosis with cures seen in >90%of children, especially if they have other favourable risk factors. Re- lapses often occur much later than those at other types of ALL. Beca use this translocation appears to occur as an early event, it has been suggested that some laterelapsesin fact derive from persistent "preleukaemic· clones that harbour the lI'ansIocalion and unde rgo additional genetic events afte r the first leukaemic cICIIe has been eliminated 17191 Children "MIh this leukaemia who also harbour ad- verse prognostic factors. such as age ewer 10 years or high white count do not have as good a prognosis, but may still lare better as a group than other patients with these same adverse factors. Postulated normal counterpart This leukaemia appears to derive from a Been progenitor rather than from a naematoooetrc stem cell 13441 B lymphob lastic leukaemia/lymphoma with recurrent genetic abnormalities 173
  • Prognosis and predictive factors Hyperdiploid B-ALl has a very favourable prognosis with cures seen in >90% of children. especially if their risk profile is favourab le Presence of adverse teeters. such as advanced age or high white count may adversely affect the prognosis, but patients may not fare as badly as otb- ers without this favourable abnormality. B Lymphoblastic leukaemiallymphoma with hypodiploidy (HypodiploidALL) Definition A neoplasm of Iymphoblasts committed to the B lineage whose blasts contain <46 chromosomes. A stricter definition of <45 chromosomes, and possibly even <44 chromosomes, more accurately reflects the clinical pathologic entity 115541. ICD-O code The provisional code proposed for the fourth edition ofICD-O is 981613. Epidemiology and clinical features Hypodiploid ALL accounts for about 5% of ALL overall, but if the definition is restricted to those with <45 chromosomes the figure is closer to 1%. It is seen in both children and adults. although near hap- loid ALL (23-29 chromosomes) appears limited to childhood . Presenting teamres are generally similar to those of other pa- tents with ALL standard karyotyping because the hypodiploid clone may undergo en- doredooucanon. doubl ing the number of chromosomes. reSUlting in a near diploid or hyperdiploid karyotype. Flow cytomeny can gene rally detect a clone with a ONA index <10, though this may be a minor popul ation . FISH may also de tect cells hypodi ploid for certain chromosomes, and this diagnosis should be suspected when there is a discrepancy between karyo type and FISH results with respect to the number of chromosomes present. Prognosis and predictive features. Hypodiploid B-ALL has a poor prognosis. The prognosis depends on the number of chromosomes: those with 44- 45 chromo- somes have the best prognosis! 1554). and those with near haploid B-ALL fare worst in some but not all studies [900, 15541. There is some evidence that. in con trast to other types of B-ALl. patien ts may fare poorly even if they do not have minimal residual disease follc::Nving therapy. B Lymphoblastic leukaemiallymphoma with t(5;14)(q31;q32); 1l.3-IGH Definition A neoplasm of IymphOblasts comnitted 10 the B lineage in which the blasts harbour a translocation between the IL3gene and the JG H@ gene. resulting in a variable eosinophilia. This diagnosis may be made based on immunophenotypic and qenetc findings even if the bone marrow (8M) blast count is low. ICD-O code The provision al co de proposed for the fourth edition of ICO-O is 981713. Epidemiology and clinical features This is a rare disease. accounting for <1% of cases of ALL. It has been reported 1'1 both children and adults. Presenting clinical ch aractensncs may be similar10 other patients with ALL, Of patients may present with an asymptomatic eosino- philia,and blasts may noteven be presen n the PB 10 raise the suspicion of Ieu~. MorpOOlogy and cytochemistry Blasts in this neoplasm have Ihe typical morphology of Iymphoblasts. but the striking finding is the presence ot an increase in circulating eosmcotes.This 1$ a reactive population and not part of the leukaemic clone. Immunophenotype Blasts have a CD19+C0 10+ phenotype Finding even small numbers of blastswith this phenotype In a patient with eosiro- phiha should strongly suggest this diag- nosis. Morphology and cytochemistry There are no unique morphologic or cytochemical features that distinguish this from other types of ALL Immunophenotype Blasts have a Bcprecursor phenotype, typically C019+. C01O+ but there are no other distinctive phenotypic features. Genetics All patients by definition show loss of one or more chromosomes, having from 45 chromosomes to near haploid. Structural abnormalities may be seen in the remain- ing chromosomes though there are no specific abnormalities that are characteris- tically associated Structural abnormalities are uncommon in near-haploid B-ALL The diagnosis of near haploid or low hypodiploid B-ALL may be missed by 174 Precursor lymphoid neoplasms Fig. I .10 BIymphoblastJc ~ with l(5;14MQ31:Q32j. Bone manow smear sl'kMnga jXlIlAbCrId typicaIlymphobIasls along Wlth I'U'l'l9fOO$ mature eosinophil$. Thegrar.J1e Iislnbubon insome 01 the ~ illJI- usual,bullhisisnot aconsisIenl lactor.
  • Genetics The unique characteristics of this neoplasm derive from a functional re- arrangement between the fL3 gene on chromosome 5 and the IGH@ gene on chromosome 14, resulting in constitu tive overexoresson of the IL3 gene 18461. Functional consequences of this re- arrangement other than eosinophilia. if any. are not well understood. The abnor- mality is typically detected by standard karyotyping; it can also be detected by FISH. though appropriate probes are not widelyavailable. Prognosis and predictive features Theprognosis is no! considered to be dit- lerent from other cases of ALL. though there are too few cases 10 be certain . Blast percentage at diagnosis is not known to be a predictive tacror. BLymphoblasticleukaemia! lymphoma with 1(1;19) (q23;p I3.3); E2A·PBXl (feF3-PBX1) Definition This is a neoplasm of lymphoblasts com- mitted to the B lineage with a t(1;19) uaosrocatron between the E2A(TCF3) gene on chromosome 19 and the PBX1 geneon chromo some 1. ICD.Q code The provisional code proposed for the fourth edition of ICD-O is 981813. Epidemiology and clinical features This leukaemia is relatively common in children, accounting for about 6% of cases of B-ALL. It is also seen in adults. but not at as high a frequency. Presenting features are generally similar to those of other patients with ALL. _ logyand cylochem;stry There are no unique morphologic orcyto- chemical features that distinguish this from other types of ALL. Immunophenotype Blasts typically have a CD19+.CD10+ cytoplasmic u (ctJ) heavy chain-positive ore-e-ceu phenotype. although not all cases of pre·B-ALl have the t(1:19). This leukaemia can be suspected even when cu is not determined as these teukaemias typically show strong expression of COO and lack CD34, or show very limited CD34 expression on only a minor subset of leukaemic cells 12441. Genetics The E2A-PBX1 translocation results in the production of a fusion protein that has an oncogenic role as a transcriptional acti- vator, and also likely interferes with the normal function of the transcription factors coded by E2A and PBXt 112621. The functional fusion gene resides on chro- mosome 19, and there may be loss of the derivative chromosome 1 in some but not all cases , resulting in an unbalanced translocation. Gene expression profiling studies have shown a unique signature to this lesion 124691. An alternative E2A translocation t(17:19) occurs in rare cases of ALL involving the HLF gene on chro- mosome 17and is associated with a dis- mal prognosis. Thus demonstration 01an E2A rearrangement by itself is not a diagnostic criterion for this leukaemia. A subset 01 B-AlL, usually hyperdiploid B-ALL has a karyotypicaIIy idenlicall( 1;19) translocation that involves neither E2A nor PBX1 and sholAdnot be confused with this entity. Cases of B-All with t(1;19) that lack the expected phenotype probably do not represent E2A-PBXl B-Al L. PrognosiS and predictive features In early studies, E2A-PBX1 was associ- ated with a poor prognosis, but fhis is now readily overcome with modern intensive therapy. Many treatment protocols no longer require identification of this genetic lesion, but the findings of unique immune- phenotypic and genetic features supports its inclusion as a distinct entity. B lymphoblastic leukaemla/lymphoma WIth recurrent genetic eboomautes 175
  • T lymphoblastic leukaemia/lymphoma M.J. Borcwttz J.K.C. Chan with very conde nsed nuclear chromatin and no evident nucleoli 10 larger blasts with finely dispersed chromatin and rela- tively prominent nucleoli. Nuclei range !rom round to irreglJar to con'lOluted,Cytl>' plasmic vacuoles may be present. occa- sionally blasts of T-Al l may resemble more mature lymphocytes; in such cases immunophenotypic studies may be re- qu ired to d istingu ish this disease Irom a mature (peri pheral) t-een leukaemia. In 8M sections the Iymphoblasts have a high nuclear/cytoplasmic ratio, thin nuclear memb rane. finely-s tippled chromatin and inconspicuous nucleoli. The number of mitotic figures is reported to be higher in T-ALL than B-ALl. In T-LBL, the lymph node ge nerally shows com plete ettace- ment of arch itecture and involvemen t of the ca psule. Partial involvement in a para- cornea! location with sparing of germinal centres may occur- Sometimes, a multin- odular pattern is produced due to stretch- ing 01the fibrous framework, mimicking follic ular lymphoma. A starry-sky effect may be present, thus sometimes resem- bling Burkln lymphoma, although typically the nucleoli arld cytoplasm are less prominent. The blasts can have round or convolu ted nuclei, Mitol ic figures are often numerous. In the thymus, there is extensive replacement 01 the Ihymic parenchyma and permeative infiltration. Cases with histological findings 01T-LBL with a significant infiltrate of eosinophils among the lymphoma cells may be associated with eosinophilia and myeloid hyperplasia and a Bp 11.2 cytogenetic an in utero origin at the earliest ge netic lesions. on _~",1 Fig.9.11 T-lymphoblasticleukaemia, A Blood smear.The Iymphoblasts varyinsizefrom large cellstosmall cells with a very highnuclear/cytoplasmic ratio, B Bone marrow section. Clinical features T-ALL typically presents with a high leuko- cyte count, and often a larg e med iastinal mass or other tissue mass. l ymphadeno- pathy and hepatosplenomegaly are cam- mon. For a given leukocyte count and tumour burden, T·Al L patients often show relative sparing of normal 8 M haerneto- poiesis compared with 8-ALL T-lBL frequently presents with a mass in the anterior mediaslinum, often exhibit- ing rapid growth, and sometimes pre- senting as a respiratory emergency. Pleural effusions are corrmon. Sites of involvement The 8M is involved in all cases 01 T-All, and in contrast 10B-All, aIet.Jkaenjc presentations in the face of8M replacement are UI'"ICO'MlOfl . T-L8l frequently shows mediastinal (thymic) invotvement, though it may involve any lymph nod e or extra- nodal site. Skin, tonsil, liver, spleen, cen- tral nervous system and testis in males may be involved, although presentation at these sites without nodal or mediastinal involvement is uncommon. Mar_The Iymphoblasts in T-AlL..A..8 L are mor- phologically indistinguishable from those of 8-AlLJL8 L. In smears, the cells are of medium size with a high nuclearl cytoplasmic ratio; there may be a consid- erable size range from small !ymphoblasts Etiology One study reported T-ALL in monozygotic twins that share the same t-een receptor gene rearra ngement 17201. suggesting Definition T lymphoblastic leukaemia/ lymphoblastic lymphoma is a neoplasm of Iymphoblasts committed 10 the t-een lineage. typ ically composed of small 10medium-sized blast cells with scant cytoplasm. moderately con de nsed to dispersed chromatin and inconspicuous nucleoli, involving bone marrow (8M) and blood (T-acute lympho- blastic leukaemia, T-AL L) or presenting with primary involvement of thymus, nodal or exlranodal sites (T-acute lymphoblas- tic lymphoma, T-LBL). By convention. the term lymphoma is used when the process is confined to a mass lesion with no or minimal evidence of peripheral blood (PBl and 8 M involvement. With extens ive 8M and PB involvement, lymphoblastic leukaemia is the appropriate term . It the patient presents with a mass lesion and Iymphoblasts in the 8M. the d istinction be- tween leukaemia and lymphoma is arbi- trary. For many treatment protocols. a figure 01 >25% 8M blasts is used as lhe threshold lor defining leukaemia, In con- trast to myeloid leukaemias. mere is no agreed -upon lowe r limit lor the percent- age 01blasts required to estab lish a diag- nosis 01 ALL In general, the diagnosis should be avoided when there are <20% blasts, ICD-D code The provisional code proposed lor the fourth ed ition of ICD-Q is 983713. Epidemiology T-ALl comprises about 15% 01childhood ALL; it is more common in adolescents than in younger children and more common in males than in females. T-ALl comprises ap proximately 25% of cases of adult ALL T-l Bl comprises approxi- mately 85-90% of all lymphoblastic lymphOmas; similar to its leukaemic coun- terpart , it is most frequent in adolescent males but may be seen in any age group. • 176 Precursor lymphoid neoplasms
  • abnormality inyolving the FGFR1 gene 13, 10061 (See Chapter 3). Cytochemistry TIymphoblasts frequently show focal acid phosphatase activity in smear and imprint preparations. though this is not specific. Irrmunophenotype The Iymphoblastsin T-ALlABL are usually TdTpositive and variably express COla, C02, COO, C04, CDS, C07 and COB. Of these, C07 and cytoplasmic C03 (cC03) aremost often positive, but 01 these only C03 is considered lineage specific. C04 and COB are frequently co-expressed on the blasts, and C010 may be positive. These latter phenotypes are not specific for T-AU as C04 and COB double posi- tivity may be seen in T-PLl and C010 in peripheral t-een lymphomas, most com- monly angioimmunobiastic r-ceu lym- phoma. In addihon to TdT, the most specuc markers to indicate the precursor nature of TIymphoblasts are CD99, CD34 andCOla: the first of these is most useful 118521. In 29-48% of cases. there is nu- clear staining for TAl· l , but this does not necessarily correlate with presence 01 TAL-1 gene alteration 1407. 543J, CD79a positivity has been observed in approximately 10% of cases 117501. One or both of the myeloid associa ted antigensC013 and CD33 are expressed in 19- 32% 01cases 11 139, 22771. COl17 (c-kil) isoccasionally positive; such cases havebeen associated with activating mu- tations of FLT31 16771. The presence of myeloid markers does not exclude the di- agnosis of T-ALLjLBL, nor does it indicate mixed phenotype T/myeloid leukaemia. Many markers characteristic of immature t-eens such as C07 and C02, and even CD5 and cCD3 may also be seen in natural killer cell precursors [20701. Thus it may be very difficult to distinguish the rare true NK precursor All from T-AlL that expresses only immature markers. C056 expression. while characteristic of NK-cells, does not exclude t-een leukaemia. T-ALUlBL can be stratified into different stages of intrathymic differ- entiation according to the antigens expressed: pro-T (cC03 +, C07+. C02-. COl ao. C034+/-); pre-T (cC03+, C07+. C02+. COlao. C034+f-); co-nee! T (cC03 e-, C07+. C02+, cora-. C034-) and medullary T (cC03+. C07 +. C02+, COla-, CD34-. surface COO+). The pro-T and pre-I stages are double-negative to- C04 and C08. and the co-neat T stage shows a double-positive (C04+ COB+) phenoty pe. The medullary T stage ex- presses only either C0 4 or C08 1187, 8791. Some studies have shown a corre- lation between the stages of T-cell differ- entiation and survival 15001· T-ALltends to show a more immature immuno- phenotype compared with T·lBL but the groups overlap 123761· Genetics Antigen receptor genes T-AlULBL almost always shows clonal rearrangements of the T-cell receptor genes (TCR), but there is simultaneous presence of IGH@gen e rearrangements in approximately 20% of cases 11749, 2138). Fli- ' .13 TIyrnphobIasllc 1eIJkaerRa. 1I'I this example. the IyrnphobIastsIaci nudear convoIution$ The dVo- matil islilely$~. Cytogenetic abnormalities and oncogenes An abnormal karyotype is found in 50-70% of cases 01 T-AlUlBl /830. 8791. The most common recurrent cyto- genetic abnormality involves the alpha and delta TCR loci at 14Q11.2. the beta locus at 7Q35, and the gamma locus at 7p14-15. with a variety 01 partner genes {830. 8791. In most cases. these translo- cations lead to a dysregulation of tran- scription 01 the partner gene by juxtaposition With the regulatory region of one of the TCR loci. The most commonly involved genes include the transcription factors HOX 11( TLX1) (lOq24) occurring in 7% of childhood and 30% of adult T-Al L, and HOX1 IL2 (TLX3) (5q35), oc- curring in 20% of childhood cases and 10-15% of adult 18301. Other transcrip- tion factors that may be involved in translocations include MYC (8Q24.1), TAU (l p32), RBTN1 (LM01) (11p15), RBTN2 (LM02) (11p13) and LYL1(19p1 3) 1519, 830) The cytoplasmic tyrosine ki- nase LCK (1p34.3-35) can also be FlO- ' .12 T/ynllI'lObIaStic1'fnllhOma. Alow ~tion 01 a tyn'4lh rode ~ ~ repIac:ement by~ 1ympI'loma. Nwerous IrIgibIe 00dyrnacropnages ll(ll scauered fYoul1IOul the rode. B H9'I rnagM:atlorl ollhe specimen lin (A) s/'JcJwWlg ~ WIltI I'llUI"d toovalto ~-s/'Iaped nudei withdisperse(l etvorna!Jn a"d lis- ra bul nollllUSUaly PfOIl'W*'Il ru:W. 5eYeraI nvloIic ligIns enpreset'( T lymphoblastic leukaelTllaJlymphoma 177
  • Fig. 9.14 T ~!ynllhoma. lowmagriflcabon stowi"lg a~a~pattem ltlalcan sometimes ITWlIC IoIil::l8" lymphoma. • involved in a translocation. In many cases transiocanons are not detected by karyo- typing but only by molecular genetic stud- ies. Forexample, the TAL 1locus is altered by translocation in about 20-30% of cases of T-ALL. In only about 3% of cases can a t(1, 14)(p32;q1 1) translocation be detected, but much more often it is fused to the SIL gene as a result of a cryptic in- terstiti al deletion at chromosome 1p32 1281,914, 10461, Aberrant TAL1 expres- sion interferes with differentiation and pro- liferation by inhibiting the transcri ptional activity of E47jH EB {16151. Other impor- tant translocations in T-ALL include PICALM-MLLT10 [CALM-AF 10, t(10:11) (p13:Q14)), occ urring in 10% of cases, and translocations involving MLL (8%), most often with the partner ENL at 19p13 {B301. Neither of these is T-ALL specific, as the first occurs in AML and the second in B-ALL. Abe rrant expression of TAL1, LYL1, HQX11 and HOX11L2 appear to be mutually exclusive from each other and also from PICALM and MLL transioca- tions, suggesting non-overlapping, patho- 178 Precursor lymphoid neoplasms genetically distinct subgroups (5191. Deletions also occur in T-ALL. The most important is del(9p), resulting in loss of the tumour suppressor gene CDKN2A (an inhibi tor of the cvcun -oepenoent kinase CDK4). which occurs at a frequency of about 30% by cytogenetics, and a higher percentage by molecular testing. This leads to loss of G1 control of cell cycle. About 50% of cases show activating mutations involvi ng the extracellular heterodimertzation domain and/or C4 terminal PEST domain of the NOTCH 1 gene , which encodes a protein critical for early t-een developm ent {2385}, The direct downstream target of NOTCH1 appears to be C-MYC, which contributes to the growth of the neoplastic cells [23861. According to one study, NOTCH1 mutation is associated with shorter sur- vival in adult but not paediatric patients {24gB}. In about 30% of cases, there are mutations in hCDC4 gene. a negative reg- ulator of NOTCH " These missense muta- tions result in increased half-lite ot the Notch1 protein {13751. Gene expression profiling studies have identified several gene expression signa- tures. some of which correspond tospecific stages of normal thymocyte development: LYl1+ signature corresponds to pro-T stage. HOX11+ to early cortical stage, and TAL1+ to late cortical thymocyte stage /6891. The HQX11+ group appears to have a relatively favourable prognosis. Postulated normal counterpart t-een progenitor (T-ALL) or thymic lym- phOCyte (T-LBL). Prognosis and predictive factors T·ALL in childhood is generalty considered a higher risk disease than B-AlL though this is in part due to the frequent presence of high-risk clinical features (older age, higher while blood cell count). HO'Nevet", T-ALL patients without high-risk features dOnot fare as well as B-ALL standard risk patients unless intensive therapy is given. Compared to B-ALL patients, T-All patients have increased risk for induction failure, early relapse and isolated eNS re- lapse 18091_In cont rast to B-ALL. while count does not appear to be a prognostic factor. The presence of minimal residual disease following therapy is a strong adverse prognostic factor 124061. In adult protocols, T-ALL is treated similarly to other types of ALL. The prognosis of T-ALL may be better than B-ALL in adults. though this may reflect the lower incidence of adverse cytogenetic abnormalities. The prognosis of T-LBL. as with other lym- phomas, depends on the age of the patient, stage and LDH levels /15121. Rare cases of indolent T lymphoblastic proliferation involving the upper aerodi- gestive tract, characterized by multiple local recurrences but no systemic dis- semination, have been desc ribed 12106. 23231. These cases are morphologically and immunophenotypically indistinguish- able from T-l BL. but lack clonal re- arrangements of the TCR genes. __________________________----'1
  • • • • ~ . 4 '.• •• • CHAPTER 10 Mature B·cell Neoplasms • -• Chronic lymphocytic leukaemia Ismail lymphocytic lymphoma B-cell prolymphocytic leukaemia Splenic marginal zone lymphoma Hairy cell leukaemia Splenic tyrnphomaIIeukaemia, unclassifiable Lymphoplasmacytic lymphoma Heavy chain diseases Plasma cell neoplasms ExtranodaI marginal zone lymphoma 01 mucosa-associated lymphoid tissue (MALT lymphoma) Nodal marginal zone lymphoma FoUicular lymphoma Primary cutaneous follicle centre lymphoma Mantle cell lymphoma Diffuse lerge B-ceillymphoma (DLBCL), NOS T-ceUhlistiocyte-rich large s-.celllymphoma Primary DLBCL 01 the CNS Primary cutaneous DlBCL, leg type EBV positive DLBCL of the elderly DLBCL associated with chronic Inflammation Lymphomatoid granulomatosis Primary mediastinal (thymic) large B-eelllymphoma Intravascular large 8-celilymphoma ALK positive large B-ceillymphoma Plasmablastic lymphoma Large B-ceillymphoma arising in HHV8-associated multicentric castleman disease Primary effusion lymphoma Bur1<itt Iymphome B-ceillymphoma. unclassifiable, with features intermediate between DLBCL and Bur1<itt lymphoma B-celllymphoma. unclassifiable. with features Intermediate between DLBCL end classical Hodgkin lymphoma • - & -. .....- ,"
  • Chronic lymphocytic leukaemia/small lymphocytic lymphoma H.K. Muller-Hermelink E. Montserrat D. Catovsky E.Campo NL Harris H. Stein Epklemiology Cll is the most common leukaemia of adults in Western countries . The incidence rate is abon 2-6 cases per 100,OCO person per year, increasing with age reaching 12.81100,000 at age 65, the mean age at diagnosis 11888]. It is now diagnosed more often in younger individuals 15251. e ll has a male:female ratio of 1,5-2:1. CLUSll accounts for 6.7% of non-Hodgkin lym- phomas in biopsies (511. It is very rare in far Eastern countries. This low incidence is maintained in migrant populations speak- ing in favour of a genetic predisposition. Definition Chronic lymphocytic leukaemia/small lym- phocytic lymphoma (CLl/SLL) is a neo- plasm composed of monomorphic small, round to slightly irregular B lymphocytes in (he peripheral blood (PS), bone marrow (8 M), spleen and lymph nodes. admixed with prolymphocytes and parammuno- blasts forming proliferation centres in tissue infiltrates.The CLUSlL ceus usually coexpress COS and CD23. In lhe ab- sence of extramedullary tissue involve- ment. there must be ~5x l ()91l monoclonal lymphocytes with a ell phenotype in the PB. The intemanoret Workshop on Chronic Lymphocytic Leukemia (IWell) report requ ires that the lymphocytosis be pres- ent for at least 3 months and also allows for the diagnosis of eLL to be made with lower lymphocyte counts in patien ts with cytopenias or disease-related symptoms 1873AI. Whether patients who would have fulfilled the Criteria In the past for Cll but who luHili the criteria only for monoclonal B lymphocytosis (MBl) are better consid- ered 10 have low stage Cll or MBl remains to be determined. Some may prefer to sun consider many of these cases more like Cll. The term Sll is used for non-leukaemic cases with the tissue morphology and immunophenotype of Cll. The IWCl l def- inition of Sll requires lymphadenopathy, no cytopen ias due to BM infiltration by Cll./Sll and <5x 1CP/lPB e-ceus [873AI. Monoclonal B-cell lymphocytosis Healthy individuals may show monoclonal or oligoclonal Been expansions with the characteristic phenotype of e ll in about 3.5% of tested subjects >40 years old ]1395, 1823). Monoclonal B·ceil lympho- cvtosis with a non-cu. phenotype (CD5-) may correspond to similar phenomena in other B-cell neoplasms [301. Whether MBl is a predisposing condition orevena precursor ofovert CLL has to be elucidated. Clinical features Clinical features are very variable including presentation, course and outcome. Most patients are asym ptomatic, but some present with fatigue, autoimmune haemo- lytic anaemia, infections, sple nomegaly, hepatomegaly, lymphadenopathy orextra- nodal infilt rates 1221, 18051. A small M-eomponent may be found in somepa- tients . Etiology B-ce ll receptors (BCR) of Cll ce lls demonstrate high ly selected immun o- globulin heavy chain variable (lGHV) gene usage or even very similar entire antigen- bind ing sites, coded by both heavy and light chain genes, and thus differ from the much broader diversity found in normal B lymphocytes. These findings argue in favour of a limited set of (auto-)antigens promoting division of precursor cells and clonal evolution 1423, 1153,22431. ". C' ~ . """'" .'30'''''' s ·l ~...... ~.'" ..Fig.10.01 AALymph nodein'o'Olved bydllooic~ leukaemja, showing regularty·spacedproliferation centres in a dar1l background (Giemsa stain). B High mllQflilicatiorl ilIustrabng a mixture of small lymphocytes withsen C'r'JPIasrn<r'ldclrrl>ed dYomattn. SOOlasIig1Iy larger ~ wiIIllTO'e disper$ed cMmabn and small ~ and single paralnwnunoblasts (arrows), lIIrtlidl are largercells WIth I'OIJnd tooval nudei, dispersed chromalJn and a """"- Sites of involvement Peripheral blood and BM are usually involved, lymph nodes, liver and spleen are also typically infiltrated, and other exira- noda l sites may occasionally be involved. Rarely, patients with ClllSLl present with aleukaemic tissue involvement, but usu- ally develop BM and PB involvement dur- ing the evolution 01 the disease. 9823/3ICD-O code , 180 Mature 8'<e1l neoplasms
  • -logy Lymph nodes and spleen Enlarged lymph nodes in patien ts with CLLlSl L show effacement of the archi- tecture , with a pseuootomcurar pattern of regularly-distributed pale areas corre- sponding to proliferation centres contain- ing larger cells in a dark bac kground of small cells 11 84, 12731. Involvement may be limited 10 inle rfollic ular areas. The pre- dominant cell is a small lymphocyte, which may be slig htly larger than a nor- mal lymphocyte, with clumped chromatin, usually a round nucleus, and occas ionally a small nucleolus. Mitotic activity is usu- ally very low. Proliferation centres contain a continuum of small, med ium and large cells.ProIymphocytesare smallto medium- sized cells with relatively c lumped chro- matin and smallnucleoli; parairrmunoblasts are larger cells with round to oval nuc lei, dispersed chromatin, cen tral eosinophilic nucleoli and slightly basophilic cyto- plasm. The size of proliferation centres and number of paraimmunoblasts vary from case to case, but there is no corre- lation between tymph node histology and clinical course 11841. In the spleen , white pulp illV'Cllvement is usually prominent. but the red pulp is also involved; proliferation centres may be seen but are less con - spicuous than in lymph nodes. In some cases, the small lymphoid cells show moderate nuc lear irregularity, which can lead to a differential diagnosis of mantle cell lymphoma {2351· Some case s show plasmacytoid differentiation. Bone marrow and blood On BM and PB smears, CLL cells are small lymphocytes with clum ped chro- matin and scanty cytop lasm 11 9 11. Smudge or basket cells are typically seen in PB smears, The proportion of prolym- phocytes (larger cells with prominent nuc leoli) in PB films is usually <2%. In- creasing number s correlate with a more aggressive d isease course. More than 55% prolymphocyles, however, would favour the diagnosis of B-cell prolympho- cytic leukaemia (B-PLL). Atypical CLL shows less condensed nuclear chromatin and nuclear irregularities in PB lympho- cytes. These findings are more frequent in cases with trisomy 12 and other chro- mosomal abnormalities {1911. Bone mar- row involvement as seen in treph ine biop sies may be interstitial, nodular and/or diffuse {1509, 18881: proliferation centres are less common in the 8M than in lymph nodes; paratrabecurar aggre- gates are not typical. The definition 01 minimal 8 M involvement required to diag- nose CLlISLL in the absence of other defining features is not established, although the IWCLl describes >30% lym- phoid cells as "charactenstcanv" present 18l 3AI lmmunophenotype Using flow cytometry, the tumou r cells ex- press dim surface IgM/lgD, C020, C022, COS, C019, C079a, C023, C043 and Co11c (weak). COlO is negative and FMC7 and CD79b are usually negative or weakly expressed in typical CLL. The im- munophenolype of PB lymphocytes has been integrated into a scoring system that helps in the differential diagnosis between CLL and other B-cell leukaemias 1t 430, 15111 , In tissue sections. cytoplasmic Ig may be detectable, and cvcun 01 is neg- ative 125081; however cvcnn 0 1has been detected in cells of the proliferation cen- tres 116141. Some cases may have an atypical immunephenotype (e.g COS- or C023-, FMC7+ or C01 1c+, strong slg, or C079b+) 1492,14291. Genetic susceptibility CLL has the highest genetic pred isposi- tion of all haernatologic recotases.A fam- ily predisposition can be documented in 5-10% of patents withCLL based on find- ing 2 or more cases in the same family. The overall risk is 2-7 times increased in Chronic lymPhocytIC leukaemialsmalllymphocytic lymphoma 181
  • Fig. 10.05 Aow t)'1omeIJy detection of ZANO in ClL. The left pIol shows tie selecbon of the ~ subpopWbons ac:etlIding tothe ~ (T-<:eIs indar1l blue.NK<eIII iI'llight blue. CI..LcellsiI'lllf'llllge andresdJaI normal B-cells n grey). The CLlcellsate C05+ (see n left plot) arw:l CD19+ (seen II otherpIols). Theplotin !hecen- trll showsaCLlwilh noIN'·70 expression (2".4 positive CI..L cells) and the plotonthe right aCI..L with t9 ZAP·70 e.pression (65% positive CLlcelli). CLl cases withmote than 20%ZAp·70e~ are usuallyconsidered as positive. , firsl degree tetanves of Cll patients 1810, 19901. Family members of patients with Cll show an increased incidence of ell- phenotype monoclonal Been lympho- cytosis at all ages, but especially in thase <40 years old 15301. Genetics Antigen receptor genes IG genes are rearranged with 40- 50% of cases unmutated (>98% homOlogy with germline) and 50-60% showing somatic hypermutation 1505, 8761. These two sub- types differ in many other biological and clinical parameters. IGHV gene usage in Cl l is highly selective, and etten associ- ated with autoantibody reactivity 11658), BCR signaling is most important in unmu- tated ell 1403, 538, 1252). Gene expression profiling Mutated and unmutated Cl l show a sin- gle distinctive signature, although there is a group of genes that distinguishes these two genetic subtypes 11160. 18671· The tyrosine kinase ZAP-70 is among the genes whose expression is associated with an IGHV unmutated Cll genotype 124021. Ftowcytometry assays for ZAP-70 have been developed as a surrogate for Cll mutational status; however, in up to 20% of the cases the mutational status and ZAP-70 expression are discordant 1490, 1653, 18221· Cytogenetic abnormalities and oncogenes About 80% of the cases have cytogenetic abnormalities detected by FISH 16011. About 50% of Cll show del 13q14.3, about 20% trisomy 12 and, less com- monly. deletions of 11q22-23, 17p13 and 6q21 1601 ,1196. 1197,1 4291. Thedistri· button of these abnormalities varies based on mutational status. The possible Tab1l 10.01 Retation ofVHmutaliOn slalusandgenorNc abefrationl ll CLl(1197) Abemtion Mutated VH Unmutated VH 11"'132 (44%) n:168 (56'1l.) cmaI aberTMon& 80'10 84'4 ~3q ~. 65"4 (8'Il. Isolaled 13qdeleIO'l' 50"4 26'Il. iTriSOmy 12 15"4 19"4 11qdeleIIon' 4% 271i. 17p~' 3% 10"4 17por11qdelebon' 7"4 35'4 • Signi~cant dll!$!tlfICe belWeen cases 'Mlh and WIth· outVH mutations. 182 Mature B-cell neoplasms targets in the 13q14.3 region are two micro-RNA genes, miR-16-1and miR-15a, ATM in the l1q22-23 region and TP53 in the 17p13 region 1475, 601, 19571. A spe- cific micro-RNA expression signature that includes miR-16-1 and miR-15a has been reported to distinguish between mutated and unmutated Cll and ZAP-70 negative versus positive Cll13151. Postulated normal counterpart Antigen experienced B-<:eIl14241. Prognosis and predictive factors The Rai and Binet clinical staging systems are used to define disease extent and prognosis 1221, 18051. New biolog ical prognostic factors have become increas- ingly important especially in early stage CLL1222, 1129, 1986J. Patientswithmutated Cl l have a better progno sis than those with unmutated Cll, at least for those with a low stage (median survival 293 months versus 95 months for patients with Binet stage A) 18761. Expression of ZAP-70 and CD38 are both associated with an adverse prognosis 17901. Dell1 q22·23, del17p and del6q are associated with a worse outcome and isolated del 13q14.3 is associated with a more favourable clin- ical course 1475, 6011. Usage of VH3-21 independent of VH mutation status is an adverse prognostic marker 122441. Addi- tional adverse predictive factors inctude a rapid lymphocyte doubhog time in the PB «12 months) and serum markers of rapid celt turnover. including elevated thymidine kinase, sCD23 and ~·2 micro- globulin 12221. Progression and transformation of Cl l to high grade lymphoma Over time, Cll may show an increase in cell size and proliferative activity as well as confluence 01proliferation centres in lymph nodes and BM. Often, this may correlate With an increase in prolymphO- cvtes in the PB. Progression of ell to B-PLl is extremely rare. 2-8% of patients with Cll develop dif· fuse large B-<:elllymphoma (OlBClj and <1% develop classical Hodgkin Iyr1'lpt"ona (Hl) 12691. The median survival for pa- tients with DlBCl (Richter's syndrome) is less than one year. The majority Of the DlBCl have been reported to be clonally related 10 the previous Cll and are un- mutated. whereas the cioneuv unrelated cases 01 DlBCl usually occurred in rnu- tated Cll 11385, 22401. The vast majority of Hl cases occur in mutated ClL. Epstein-Barr virus (EBV)-associated Hodgkin Of Reed-Sternberg (RS) cells frequently are unrelated to the Cll clone 11 3851. Some Cll cases show scattered EBV· positive or sometimes negative Reed- Sternberg cells in the background of Ctt. These cases should not be diagnosed as Hodgkin lymphoma. The diagnosis of Hodgkin lymphoma in the setting 01 CU requires classical RS cells in an aoorcon- ate background. EBV-associated Iympho- proliferative disorders including Hodgkin lymphomas may occur after fludarabine therapy 14. 22341.
  • • B-cell prolymphocytic leukaemia E. Campo 0 , Catovsky E. Montserrat H,K, Muller-Hermelink N.L. Harris H. Stein Sites of involvement The leukaemic cells are found in the PB, 8M and spleen. Clinical features Most patients present with B symptoms, massive splenomegaly with absent or minimal peripheral lymphadenopathy, and a rapidly rising lymphocyte count, Epidemiology B-PLl is an extremely rare disease, com - prising approximately 1% 01 lymphocytic leukaemias. Most patients are over 60- year-old. with a median age of 65-69 and similar male.temale distribution 11456 1. Genetics Antigen receptor genes Immunoglobulin genes are clonally re- arranged with an unmutated heavy chain gene in about half of the cases. All B--PLL of a central eosinophilic nucleolus 118921. l ym ph nodes show diffuse or vaguely nodular infiltrates of similar cells . Prolifer- ation centres (pseudofollicles) are not seen. Oistinctioo from blastoid variants of MCl . splenic marginal zone lymphoma. and Cll with an increased number 01 prolym- phocytes may be difficult 00 morphologi- cal grounds. The differential diagnosis requires immunophenotypic and genetic studies. in part to rule out the presence 01 the t{1 1.14) translocation or cyctm 01 overexpresson. Immunophenotype The cells of B-PLL strongly express surface IgM +/- IgO as well as B-cell antigens (C019, C02O . C022. C079a and b. FMC7) : COS and C023 are ooly positive in 20-30% and 10-20% of cases, re- spectively 1542. 1194. 18921. ZAP-70 and C038 are expressed in 57% and 46% 01 the cases but they are not related to the muta- tional status 01 the immunoglobulin genes 15421· --•.• ' . ~ Tissues other than bone marrow The morphology of B-Pll in tissues is not we ll known since previous histolog ical studies have included cases with the t(11;14) translocation that correspond to leukaemic variants of mantle cell lym- phoma (MCl ) 11892.1963). The spleen shows expanded white pulp nodules and red pulp infiltration by intermediate to large ce lls with abundant cytoplasm and irregular or round nuclei with the presence usually over 1(X)x1()llA... Anaemia and thrombocytopenia are seen in 50% {11941. Mo<phology Peripheraf biood and bone marrow The majority (>55% and usually >90%) of the circulating cells are prolymphocytes -medium-sized cells (twice the size of a lymphocyte) with a round nucleus, mod- erately condensed nuclear chromatin. a prominent central nucleolus and a rela- tively small amount of faintly basophilic cytoplasm 1750. 14561. Although the nu- cleus is typically round. there may be some indentation in some cases. The 8M shows an interstitial or nodu lar infiltrate of nocieotateo cells with an intertrabecular d istribution. 983313IC().() code Definition B-cell prolymphocytic leukaemia (B-PLl) is a neoplasm of B prolymphocytes af- fecting the peripheral blood (PS), bone marrow (8M) and spleen, Prolymphocytes must exceed 55% of lymphoid cells in the PB, Cases 01 transformed ch ronic lym- phocytic leukaemia (ell). ell with in· creased prolymphocytes and lymphoid prQifefationSwith rela~ smlar m0rpho- logy bu t carrying the t(11;14)(q13:Q32) translocation are excluded. B-cell prolymphocytic leukaemia 183
  • • have been reoorteo to use members 01 the VH3 (68%) and VH4 (32%) gene fam- ilies 15421. Cytogenetic abnormalities andoncogenes Initial studies had demonstrated the t(11;14)(q13;q32) translocation in up to 20% 01 B-PLL 12741 However, these cases are now considered leukaemic variants of MCL {1892, 1963, 2439J Corn- plex karytotypes are common 11963J Del(17p) is detected in 50% 01 the cases 15421 and is associated with TP53 gene mutations 11 2771. This probably underlies 164 Mature B-cell neoplasms the progressive course and relative treat- ment resistance of B-PLL. FISH analysis detects deletions at 13q14 in 27% of the cases 15421. Trisomy 12 is unconvnon 15421. Postulated normal counterpart Unknown mature B-cell. Prognosis and predictive factors B·PLL respond s poor ly to therapies for eL L and median survival is 30- 50 months 1542. 18921 Neither ZAP-70 expression. CD38 positivity. 17p deletions nor the mutational status 01the immunoglobulin genes seem to correlate with survival 15421. Splenectomy may improve the patient's symptoms. Responses have been recorded with the ccnomatco CHOP (cytcxan. adriamycin. vincristine and prednisone), and the nucleoside analogs fludarabine and cladribine. A combination of chemotherapy and ntux- imab may be a reasonable approach to treat these patients 11194J
  • Splenic B-cell marginal zone lymphoma P. G. Isaacson M.A Piris F. Berger S,H. Swerdlow C, Thieblemont S, Pillaluga NL Harris Synonym Splenic lymphoma with circulating villous lymphoCytes (SLVL). Epidemiology SMll is a rare disorder, comprising less than2% of lymphoid neoplasms 179}. but it may accounttor most cases of other- wise unclassifiable chronic lymphoid ieckaemies that are CD5-, Most patients are over 50 and there is an equal sex incidence 11951. Definition Splenic marginal zone lymphOma(SMZl) is a Been neoplasm composed of small lymphocytes which surrCM.Jnd and replace the splenic white pulp germinal centres, efface the follicle mantle and merge with a peripheral (marginal) zone of larger ceus includ ing scattered transformed blasts: both small and larger celts infiltrate the red pulp . Splenic tater lymph nodes and bone marrow (8M) are often invotved: lymphoma cells may be found in the pe- ripheral blood (PSI as villous lympho- cytes Fig. 10.08 Splenic rnatgIl'IaI zone ~. Gtoss ~ 01 spleen shoIfIling m;rled e~ dh wtWIpUp. as.el asPlllralion dille redpUp, chromatin and abundant pale cytoplasm. which resemble marginal zone cells and interspersed transformed blasts. The ted pulp is always infiltrated. with both small nodules at the larger cells and sheets of the small lymphocytes, which often in- vade sinuses. Epithelioid histiocytes may be present in the lymphoid aggregates, Some cases may have a markedly pre- dominant population of the larger mar- ginal zone-li ke cells 18781. Plasmacytic differentiation may occur and in rare cases, clus ters of plasma cells may be present in the centres of the white pulp nodules, In splenic hilar lymph nodes the sinuses are dilated and lymphoma Sites of involvement The tumour involves the spleen and splenic hilar lymph nodes, BM and often the PB. The liver may be involved. Peri- pheral lymph nodes are not typ ically involved 1195, 14971. Morphology In the splenic white pulp, a central zone of small round lymphocytes surroun ds. or more commonly replaces reactive germi- nal centres with effacement of the normal follicle mantle 11 0 14, 149n This zone merges with a peripheral zone of small to med ium-sized cells with more dispersed Clinical features Patients present with splenomegaly, sometimes accompanied by autoimmune thrombocytopenia oranaemia and a vari- able presence of PB villous lymphocytes. The BM is regularly involved, but peri- pheral lymphadenopathy and extrarooar infiltration are extremely uncommon. About one third of the patients may have a small monoclonal serum protein, but marked hyperviscosity and hypergamma- globulinaemia are uncorrrnon 1195, 14971. An association with hepatitis C virus has been described in southern Europe 172, 9261 9689/3ICD-Ocode 185Splenic B-eell marginal zone lymphoma J'- ~~~_........._
  • , Fig. 10.09 SpIel'IiClTI<WgI'Ial zone lymphoma. Peripheral blood containing tumour cells with ~ar villi (villous IymptlocylesJ. surrounds and replaces germinal centres, but the two cell types (small lymphocytes and marginal zone cells) are etten more intimately admixed without the formation 01 a distinct "marginal" zone. This has given rise to doubts about suggestions that the tumour arises from splenic mar- ginal zone cells. In Ihe BM there is a nodular interstitial infiltrate cytologically similar 10that in the lymph nodes. Occa- sionally, neoplastic cells surround reactive follicles. Intrasinusoidallymphoma cells, better revealed after C020 immunostain- ing , are a helpful feature although they are sometimes observed in other lymphomas [7271. When lymphoma cells are present 186 Mature 8-eell neoplasms in the PB, they are usually, but not always , characterized by the presence of short polar villi. Some may appear plasma- cytoid 114571. The differential diagnosis includes other small Bccell lymphomasJ leukaemias. including chronic lymphocytic leukaemia. hairy cell leukaemia, mantle cell lymphoma. follicular lymphoma and Iymphoplasmacytic lymphoma. The nodular pattern on BM biopsy exclu des hairy cell leukaemia. but the morphologic features on BM examination may not be sufficient to distinguish between the other subtypes. This requires integration with the morpho- logy and immunophenotype of the cells in the PB and BM. Irrrounophenotyp Tumour cells express surface IgM and usually, but not always, IgO, are C020+ , C0 79a+, C05-, C01O-, C023-, C043- and annexin A1- P014, 14281. C0103 is usually. but not always, negative and cyclin 0 1 is absent 119451. Staining for Ki67 shows a distinctive targetoid pattern based on the presence of an inc reased growth fraction in both the germinal cen- tre (if present) and the marginal zone. The absence 01 cycnn 0 1 and the infrequent expression of C05 are useful in excluding mantle cell lymphOma and chronic lympho- cytic leukaemia respectively. Absence of ars-exm A1 excjuoes hairy ceueckaeraa. and absence 01 COlO and BCl6 helps to exclude follicular lymphoma 119451. Genetics Antigen receptor genes Immunogl ob ulin heavy and light chain genes are rearranged and approximately half 01 the cases have somatic hyper- mutation. Bias in VH1-2 usage has been found in both mutated and unmutated casessuggesting that this tumour derives from a highly selected Been population 1231. Other biased VH gene usage has also been reported 11251. In addition, intra- clonal variation has been rarely detected. suggesting ongoing mutations 1624.249n Cytogenetic abnormalities Allelic loss 01chromosome 7q31·32 has been de scribed in up to 40% of SMZL 114161. Oysregulalion of the CDK6 gene located at 7q21 has been reported in sev- eral cases of SlVL wilh translocations in- volving this region 14741. Trisomy 3q and a number 01 other cytogenetic abnormal- ities have been described 1319, 766, 859, 929, 1669llNhile BCl2rearrangement and t(14 ;18) are absent. CCNDl rearrange- ment , t(11 ;14) and cyclin 01 express ion have been reported in a small propoton 01 the cases; however, the possibility that these cases represent examples of mantle cell lymphoma has not been excluded, since cycnn 0 1 exp ression is absent Irom weu-cbaractere ec cases of SMZl119451. Translocation t(1 1;18), common in extra- nodal marginalzone lymphoma ofmucosa- associated lymphoid tissue (MALT) type. is not a leature of SMZL 1575, 18371. Splenic marginal zone lymphoma has a specific transcnptooat profile compared with other B-eell , especially small B-eell lymphomas. This specific molecular sig- nature includes genes involved in the signaling cascade of the AKT1 pathway and B-eell receptor signaling {374. 21971. Postulated normal counterpart B-ce ll of unknown differentiation stage, The prese nce 01IG gene somatic hyper- mutations in 50% of cases suggests BInfillnlbon 01 red pulp sinuses. I
  • fig. 10.11 Splenic margI'IaI ZOfIll~ . .. SpIeric!*lr Iymj:tII"IJde s/'loIWIg a nodlNr infillra1e CHigh ~ shows arrU1uredsmaI ~ and larger cells. I , I ( exposure to antigen in the germinal cen- tre microenvironment. Prognosis and pred ictive factors The clinical course is indolent, even with 8M involvement 172. 195, 1538, 2196, 219n Response to chemotherapy of the type that is typically effective in other chronic lymphoid leukaemias is often poor, but patients typically have naema- toloqrc responses to splenectomy. with long-term survival. Transformationto large B-cell lymphoma may occur, as in other indolent Bccetl neoplasms 115381. HeV- positive cases have been reported to re- spond to antiviral treatment using interferonr with or without ribovarine 1926. 21951. Adverse clinical prognostic factors include a large tumour mass or poor gen- eral health status 13741. A clinical scoring system has been proposed 1721 and cases with mutated TP53 may show an aggressive course 18581. The presence of 7q deletion and unmutated IGHV genes may be associated with an unfavourable outcome 123, 22631. Splenic B-eefl marginal zone lymphoma 187
  • Hairy cell leukaemia K. Foucar 8 . Falini D. Calovsky H. Stein Etiology Although the nature of the underlying oncogenic events in HCL is not known, severersiudies provide an explanation for many of the unique features of this entity 1157. 348,22351 (Table 10.02). Definition Hairy ce ll leukaemia (HCL) is an indolent neoplasm of small mature B lymphoid ce lls with oval nuclei and abundant cyto- plasm with "hairy" projections involving peripheral blood (PBl and diffusely infil- trating the bone marrow (8 M) and splenic red pulp. EpidemOOgy Hairy cell leukaemia is a rare disease. comprising 2% of lymphoid leukaemias. Patients are predominantly midd le-aged to elderly adults with a median age of 50 years; HCl has been diagnosed rarely in patients in their 20's, but is exceptionally uncommon in children, The male.ternare ralio is 5:11642/. Fig.10.14 Hairy oeIleukaemia. The spleenis~ enlarged wittIddIuse eqllllSion of the red pulp ....,. pulp is nol.discema ble. Numerous bloodceII lBkesof vaf}'ingsize arevisible. in contrast to the closely packed nuclei of most other indolent lymphoid neoplasms involving the 8 M. The abundant cyto- pla sm and prominent cell borders may produce a "fried-egg" appearance 1212, 19991. Mitotic figures are virtually absent. When infiltration is minimal, the subtle clusters of hairy cells can be overlooked. In patients with advanced disease. a dr!- fuse solid infiltrate may be evident. The obvious d iscrete aggregates that typify 8M infiltrates 01 many other chronic JyrTVio- proliferative disorders are not a feature of HCL. An increase in reticu lin fibres is as- soci ated with all hairy cell infiltrates in 8M and other sites, and often results in a "dry- tap ". In a proportion of patients, the 8M is hypocellular with a loss of haematopoietic elements, espec ially the gra nulocytic no- eage, which can lead to an erroneous di- agnosis01 aplastic enaeraa. In such cases, invnunostaining lor a B-eell antigen such Clinical features The most common presenting symptoms include weakness and fatigue, left upper quadrant pain, fever and bleeding. Most patients present with splenomegaly and pancytopenia with few circulating neoplas- tic cells. Monocytopenia is characteristic. Other common distinctive manifestafions include hepatomegaly and recurrent oo- portunistic infections. while less corrroon unique findings includevasculitis , bleeding disorders. neurologic disorders, skeletal involvement and other immune dysfunc- tion /951}. Morphology Peripheral blood and bone marrow Hairy cells are small to medium-sized lymphoid cells with an oval or indented (bean-shaped ) nucleus with homoge- neous, spongy. ground-glass chromatin that is slightly less clumped than that of a normallyrnphoCyte . Nucleoli are typically absent or inconspicuous. The cytoplasm is abundant and pale blue , with circum- ferential "hairy" projections on smears 1212, 19991. Occasionally the cytoplasm contains discrete vacuoles or rod-s haped inclusions that represent the ribosome lamellar complexes that have been iden- tified by electron microscopy 11999J. The d iagnosis is best made on 8M biopsy. The extent of 8 M effacement in HCl is variable. The primary pattern is in- terstitialor patchy with some preservation of fat and naematoporetrc elements. The infiltrate is characterized by wideIy...gpaced lymphoid cells withoval or indented nuclei. 994013ICD-O code Sitesof involvement Tumour cells are found predominantly in the 8M and spleen. Typically a small num- ber of circulating cells are noted. Tumour infiltrates may occu r in the liver and lymph nodes, and occasionally also in the skin. Rare patients demonstrate prominent ab- dominal lymphadenopathy, which is as- soci ated with large hairy cells; this may represent a form of transformation 119991. • •.-Fill. 10.13 Hairy cel leukaemia. smears. A,B Note 1helyf:icaI ~ fealuresoiciroJlatWlg hairycels ~ therange innuclear morphology. CThere isstrong~ tesistanl acid p/'lOSpI'IaIaSe posiMy c:IIar'aderisbc oIl1aily oeIlNaemia 188 Mature B-eeU neoplasms •
  • Property Proposed pathogeneticmechanism(s) Table 10.02 Palhogenesjs ofhairy ~Ilel;ka&miaas C020 is essential tor the identification ofan abnormal B-cell infiltrate, prompting thecedomance of more specific immuno- histochemical stains lor HCl. The pro- duction of cytokines by the hairy cells is presumed to be the cause of mrs haematopoietic suppression 13481. Other leukaemiaS/1ymphomas such as splenic marginal zone lymphomas and some urclassihable splenic Iymphomasl leukaemias show morphologic and im- munopheootypic overlap with hairy cell W<aema Spleen and other tissues In the spleen. HCL infiltrates are found in the red pulp. The white pulp is typically atrophic. The cells characteristically fill the red pulp cords. Red blood cell lakes, collections 01 pooled erythrocytes sur- rCllMlded by elongated hairy cells, are the presored consequence of d isruption of normal blood flow in the red pulp 1212. 19991. The liver may show infiltrates of hairy cells , predominantly in the sinu- soids lymph node infiltration may occur especially with advanced disease, and is variably mtertouicurarzparacorucar, with sparing of follicles and intact sinuses. Cytochem;SUy Theonly cytoc hemical stain utilized in the diagnosis is tartrate-resistant ac id phos- phatase(TRAP), and this techn ically chal - lenging cytoc hemical stain has been largely supplanted by immunophenotypic/ immunohistochemical tech niques. If ap- propriate air-dried unfixed slide prepara- tions are available, virtually all cases of HCL will contain at least some ce lls with strong, granular cytoplasmic TRAP posi- tivity, while weak staining is not of d iag- nostic utility (212, 19991. Immunophenotype The assessment of an antigen profile that takes into account intensity of antigen expression and assessment 01 multiple antigens is very useful in the diagnosis of HCl. The classic immunophenotypic pro- file of HCL consists of bright monotypic surface immunoglobulin, bright coex- pression01 C020, CD22 and COlle, and expression of C0103, C025. C0123, t-eet. Annexin A l (ANXA1), OBA.44, FMC-7 and cycun0 1(usually weak) 1348. 541 ,670, 1062, 1423, 1999 . 23921. Most cases 01 HCllack both COlO and CDS.although irrmunopheootyp variants arewelt known 1404, 10501· Annexin A1 is Hairy cellmorpI1oIogy ~tobMemamlW . ~~ ~ ill'lCl hepatic sftIsDidS "",.""""Pseudosinus bmalion f1 spleen lnhibiIion 01 noonaI haemalopoiesis (hypocelllW Hell References {157, 348,2235}. Derived fmm I'Nlturememory B-cell. Leukaemic llairyeels diller from fIOITIIal memory B.oeIls because ofaltenldeJqll"ession ofc:hemolOO8 and adhesiOn I"8ClIJlkn Inlluenced byo'<'enlllpreSSiDn and consbtuIive ~ ofmembers ofRho lamit)' ofsmaI GTPases and ~ oflhe~ eres- spetlfJcmolecule Gas7. May relatetoconstlbJtrve 8ClMIbDn ofadhesiDMootiIit rec;eplor$, tIItryoeIsI11Brad sponIaneously WIllextraeeIIAar maW; c:ornponera; MIry cellslIlJIere andbI'llI frMy ontoftbronecbn in bone nwrow miODeI'wrcnment HCleels synIheslzeandbI'llI to fibrooedin inbone ma-mw ~ eovworwnent. Proc1Jctictl meoflbonedin I5INer 00fltrtlI cJawR baSIC rtJroblast ~ IKU (bfGF) seoeled byhlwycels. Trans- lon'ring ~ tactJr lit (TGF131) also ~ a IOIe in reliwiInfbtlsis liair'fcels home to ~ Q)Ii"',enls ¥ia~ actovaIed integrin ~ and over expres:siDn cJmatIJ-mecaIDpr'o- IeinasfI mitIikn.. Down ~ 01 dWll,()Q18 rec:epkn Sl..Id1 as CCR7 iIl'ldCXCR5e~ absence 01 ~ node ~ CMl!expressiM 01 Amen'l1 and adI'I pos:stlIe rnediakn. InleraetIa1 d hairycelI5l11'iltJ 8fIdoltlIUI cellsrMl.Cing in repIacemenl ofMdDlheIiaI c:elIl byIeiukaemic hairycells. Related toconstitutrve eel aetiYllflDn. Cons1itubve prOl:b:bon ollJ.mi:U necrosis Iador(TNF),intetIeum ~ (IL-6) and 0YeI'e~ d apopt06is irhbib. BCL2_ ConstiMive PI'(lllJcliDn 01 tr.InslomW1g growth fada~ (TGF~ ) by ""'- Hairy cea leukaemia 189
  • • ~" • the most specific marker since it is not expressed in any B-cell lymphoma other than HCL 16701 Expression of Annexin A1 can be used to distinguish HCL Irom splenic marginal zone lymphoma and HCL variant which are both Annexin A1 neg ative 16701. Immunostaining for An- nexin A1 must always be compared with that lor a B-cell antigen (e.g. C020), since Annexin A1 is also expressed by myeloid cells and a proportion of t-ceus 16701. For this reason, Annexin A1 is not a suitable marker for mon itoring minimal residual disease. More suitable approaches for assessment lor residual d isease after therapy include either mutticolor llow cytometry targeting the d istinctive HCl profileorITml..nohistochemical techniques including C020, TRAP, DBA 44 and 'l-bet. However, low numbers of TRAP positive Of OBA.44 positive cells may be seen in normal BM 114231.Similarly, some t-eens may be I-bet posmve. and weak staining for T-bet may be seen in other B-cell neo- plasms 110621, The clinical value 01mon- itoring for residual disease is not yet established . Genetics Antigen receptor genes Although exceptions have been reported. the majority (>85%) of cases of HCl demonstrate VHgeneswith somatic hyper- mutation indicative of a post germinal cen- tre stage of maturation 183. 348, 22351. A unique feature of HCl is the common co- expression of multiple cronauv related 19- isotypes. suggesting arrest at some point during lsotype switching (22351. Cytogenetic abnormalities No cytogenetic abnormality is specific for HCl: numerical abnormalities of chromo- somes 5 and 7 have been described, but translocations are distinctly uncommon 13481 Postulated normal counterpart late, activated memory B-cell. F-'g,10.16 Huy cellel.taenN. A.S Bone marrow biopsy. Hypoc:eljar ha-y cel leuk.aerlia lIIilhsublIenetsbtIaI .... lillrcIles(A). lrmuIoperoxidas lorC020 ~ sublIeIeukaenic:in6Itrates inhypocelUarHCl (B). C Spleen.Red pulpi1iIlraticI'I lIIilhrunerous red bkxxlcel lal<es, 0 LiwM".Bo8l portal iI1d SinJ5CidaI irI6Ilr.3lion by~ eelsispresert Fig.10.17 Hairy cel leukae!l"ia,iml'T'l.J~ features. A,B,CBone malfOWbiopsy. AD8A44positivityothai'y eels accef1luat nghairy projedlons. B com ~tYity ot hairy cells C Hairy cees express Annexin 11'ttli1e eryttwoid prew-scn arenegaUve. 0 Uver.Sinusoidal inFiltration byAn!lexinA1-pClSjbve leukaemichairycells. Prognosis and predictive factors HCl is uniquely sensitive to either a -in- terferon or nucreosices (purine analog s) such as pentostatin and ctaonbme. Pa- tients receiving purine analogs often achieve complete and durable remissions {22351. Prolonged remission may also re- sult Irom splenectomy, but this is uncom- mon 17981. The overall tn-year survival rate exceeds 90% {642, 7981. Rituximab 190 Mature B-cell neoplasms offers therapeu tic efficacy in combination with pu rine analogs in patients with re- nactorwreiaosed HCL: experimental ther- apeutic agents incl ude anli-C022 antibody therapy or anti-C0 25 immuno- toxin therapy 118501. l ong term HCL sur- vivors have an increased risk of second cancers compared to the general popu- lation with a cumulative probability of 30% for second neoplasms by 25 years after HCl diagnosis 19401- Hodgkin and non- Hod gkin lymphomas as well as thyroid cancer predominate in these long term survivors 19401.
  • Splenic B-cell lymphoma/leukaemia, unclassifiable M. Piris K. Fouca r M. Mollejo E. Campo B. Falini Sites of involvement All cases are diagnosed at clinical stage IV, with spleen, 8M and PB involvement. Periphe ral lymph node involvemen t is only rarely reported. Epidemiology Splenic diffuse red pulp small B-cell lymphoma is a rare disorder, accounting lor < 1% of non-Hodgkin lymphomas. It represents about 10% of the B-ceil lym- phomas diagnosed in splenectomy spec- imens. Most patients are over 40 and there is no gender bias. Synonyms Splenic marginal zone lymphoma (SMZL)- diffuse variant {1496 1, lymphocytiC lym- phoma simulating hairy cell leukaemia 116811, splenic B-ceil lymphoma with vil- lous lymphocytes (also used for SMZl and HCl-vatiant), splenic red pulp lym- phoma With numerous basophilic villous lymphocytes 122621- Clinical features Splenic diff use red pulp small B-ceUlym- phoma is a leukaemic neoplasm, usually with a relatively low lymphocytosis. Al- most all patients have, frequently massive, splenomegaly. Although not consistent among all stud ies, thrombocytopenia and leukop enia are frequently pres ent. while anaemia has been reported more rarely, B symptoms are infrequent. A small group of these patients show cutaneous infiltration 959113fCD-OCOde diagnostic markers. This diagnosis should be restricted to charac teristic cases, ful- fillin g the major features descr ibed here and not applied to any lymphoma grow· ing diffusely in the spleen. Chronic 1ympho- cytic leukaemia (CU). hairy cell leukaemia (HeL), _""""YlC IynVooma (Lf'L) and prolympI-ocybC ieLl<aema (PU) should be excluded through appropriate studies, A certain d iagnosis may require the ex- amination of the spleen. but may be sug- gested to- cases showing purely intrasinusoidaJ BM involvement and villous lymphocytes in the PB. In case of doubt, the use of the term splenic Been Iym- phoma/leukaemia, unclassiliable is war- ranted . Some deg ree of overlap exists with cases that fulfil the criteria for hairy cell leukaemia variant {1913A, 14311. The neoplastic cells in both entities are 0 8A.44 +, frequently IgG+, IgO· and have frequent chromosomal alterations, Addi· tiona ! studies are req uired to confirm these findings and to further evaluate the extent of overlap between these entities, par ticu larly as not all stud ies report the same phenotypic or cytogenetic findings, A rare subtype of large B-cel l lymphoma involving the sinusoids, both in the spleen and the 8M, has been described by two different groups 11495A, 1523) , Although these cases may be related to those de- scr ibed above, the diagnosis of splenic diffuse red pulp smal l B-ceil lymphoma is restricted to an indolent lymphoma com- posed of small lymphocyt es, Definition Splenicdiffuse red pulp small B-ceillym- phoma is an uncommon lymphoma with a diftuse pattern of involvement ot the splenic red pulp by small monomorphous B lymphocytes. The neopl asm also in- volves bone marrow (8 M) sinusolos and peripheral blood (P8 ), co mmonly with a villous cytology, This is a provisional en- titythat needs add itional molecu lar stud- ies tor defining its main features and There are a number 01 variably well- defined entities that represent small Be en Clonal lymphoprolilerations involving the spleen, but which do not fall into any of the other types of B-cell lymphoid neo- plasms recognized in the WHO classift- eaton. This chapter reviews the two best oeteeo ofthese relatively rare provisional entities. splenic diffuse red pulp small B-cel lymphama and hairy cell leukaemia variant. The relationship of splenic diffuse red pulp small Been lymphoma to hairy cell leukaemia variant and omer primary splenic B-celllymphomas remains uncer- tain, the ir precise diagnostic criteria are notfully established and the most appro- pnale terrTWdogy iswserned.Other splenic small B-cell lymphomas not fUlfilling Ihe criteria lor either otmese provisional enti- tiesor for other tetter established B-eall lymphomas should be diagnosed as splenic Been Iymphomalleukaemia. uo- classifiable until more is known. Splenic diffuse red pulp small B-<elllymphoma .". ._ ~ _ .. ao flll.10,18 Sj:IIehc do1luse red pulpsmaI fk:elI~. APeripheral blood cyloIogy wrItlYiIous eel. B Reticulin stairIIog oullinn!he mixed lllfillTation 01 bolh red Pl4I CllI'Wl8I'IlS:cordsarwj SinIsOidS. CBentITWTtIW innsilusoidal ldillratlonhiQt6lt4edby C020Ulrlg SplenIC B-celllymphomalleukaen"Na. uoctassmatae 191
  • Hairy cell leukaemia-variant (HCl.v) Postulated normal counterpart Unknown peripheral blood Be en. Synonym Prolymphocytic variant of HCL. 959 1/3ICD-Q code Prognosis and predictive factors This is an indolent but incurable disease. with good responses after splenectomy. Definition The designation HCL·v encompasses cases 01 B chronic lymphoproliferallYe disorders that resemble classic HCl but exhibit variant "cvroneematotoqc" fea- tures (i.e. leukocytosis. presence 01 morocytes. cells with prominent nucl~, celts with blastic or convoluted nuclei andJor absence of circumlerential shaggy contours). variant immunophenotype (i.e. absence of C025, annexin-A 1, or TRAP) and resistance 10 conventional HCl ther· apy (r.e . lack of dramatic response to claonbme). These cases are no longer considered to be biologically related 10 HCL translocation t(9;14)(p13:q32) inIJo!ving PAX5 and IGH@genes have been fOlind in these cases 11411 bUI they lack del 7Q and t( 11:14). Frequent TP53 alterations have been described , with increased p53 expression 114961. Others have reported a frequent absence 01 any cytogenetic abnormalities and occasional cases of det 7q /22621. Epidemiology Cases of HCL-v account for about 10%of HCL with an incidence of approxrrnately 0.03 per l 00,CXXl persons per year 118501. Middle-aged to elderly patients are at- tecteo and there is a slight male predom- inance 11431 1. Cases of HCL-v have been described in Asian patients where HCl -v may be more comroon than HCL 114311. Clinical features Patients with HCL-v typically mamfesl Sites of involvement Spleen. 8M and PB are involved but hepatomegaly and lymphadenopathyare relatively uncommon /14311. Involvemert 01other solid tissues is rare. nucleoli, with scattered nucreorateo blast cells. Tumoural cells have a pale or lightly eosinophilic cytoplasm. with plasmacytoid features but lacking other featu res of plasmacytoid differentiation, such cyto- plasmic Ig or CD38 exp ression. Cytochemistry Tartrate-resistant acid prosoatase (TRAP) staining is not present. Immunophenotype The characteristic profile is CD20+, DBA44+, IgG+, IgD-, Annexin A1-, C025- , COS-, C0103-, CD123-, C011c-, C01O-, C023- P 429A, 1496, 19221. IgO+ cases can be seen with similar featu res. Others have reported cases with IgM+lgG±, CD103+ and COt tc- with infrequent CDS and C0123 expression 122621. Genetics Most cases seem to harbour a relatively low load of somatic hypermutation in the JGHV genes. No bias lor VH1.2 gene has been seen , as in SMZl. Overrepresents- tton of VH3-23 and VH4-34. as in HCl, has been reported 122621. Complex cytogenetic alterations, including Bone marrow: lntreslnusolc at infiltration is the rule, occasionally as a sale finding This can be accompanied by interstitia l and nodular infiltration, l ymphoid follicles, as in SMZl. have not been reported, in the form 01 erythematous and pruritic papules at the lime of the initial diag no- sis. Presence 01 a paraprotein has not been reported. Spleen. A diffuse pattern of involvement of the red pulp, with both cord and sinu- soid infiltration is present. Characteristic intrasinusoidal aggregates with occasional pseud osinuses lined by tumoural cells may be seen. In contrast 10 SMlL, the tumour shows an absence of follicular re- placement, bipnasc cytology or marginal zone infiltration. The neoplastic infiltrate is corcceec 01 a monomorphous population of small to medium-sized lymphocytes. with round and regu lar nuclei. vesicular chromatin and occasional d istinct small Morphology Peripheral blood: Villous lymp hoc ytes similar to those reported in SMlL are present. 192 Merure B-ceu neoplasms I
  • A . . • signs and symptoms related to either splenomegaly or cytopenias. Leukocytosis is a consistent feature with an average white blood cell count of about 35xl()9/L. while thrombocytopenia is present in about half of the patients and anaemia in one quarter 114311. The absolute mono- cyte count is typically within normal range. ""-yCirculaling HCL-v cells are readily appar- ent on the PB smear ; commonly these cells exhibit the hybrid features of pro- lymphocytic leukaemia and classic HCl . although several other morp hologic sub- types (blastic, convoluted) have also been described 11 8501, Nucl ear featu res range from condensed chromatin with prominent central nucleoli of a prolympho- cync cell to dispersed chromatin with highly irregular nuclear contours. Cyto- plasmic features are similarly variable, al- though some degree of hairy project ions istypicallynoted 13731 Transformation to large cells with convoluted nuclei has been described and cases of so-called convoluted HCL may be explained by this phenomenon 114311. Unlike Classic HCL, the8Mis aspirable without significant reli- culin fibrosis13731_The infiltrates of HCL-v may be subtle and very inconspicuous, otten requiring irrmunohistochemical stains to high light the pattern and extent of infiltration 13731. Recent publicati ons note a distinct predilection lor nearly ex- clusive sinusoidal infiUration 1373, 1431, 24601 Similar to HCL and splenic diHuse red pulp small Been lymphoma. the red pulp of the spleen is dittuselv involved and ex- pan ded in HCL-v, resulting in atretic or absent white pulp follicles. The leukaemic cells fill dilated slnusoios and red blood cell lakes may be noted 11431] Liver involvement is characterized by both portal tract and sinusoidal infiltrates. Cytochemistry Unlike classic HCL, cytochemica l staining for tartrate-resistant acid pnospetase (TRAP) is weak to negative in HCl -v (541. 1431, 18501. Immunophenotype Cases of HCl·v share many immuno- phenot ypic and immunohistochemical (IHe) features with HCl , although HCl·v cells characteristically lack several key HCl antigens usually includ ing C025. Annexin A1, TRAP-IHC. C0123 and HC2 1670, 1431, 18501. Positive "markers" in HCL·v include DBA.44. pan-B-cell anti- gens. COlle. bright monotypic surface immunoglobulin (more frequently IgG), CD 103 and FMC711423. 14311. Genetics There are no known specific genetic changes. Some cases demonstrate com- plex cytogenetic abnormalities involving t 4q32 or 8Q24 and TP53 deletions 114311. Postulated normal counterpart Activated Been at late stage ofmaturation. Prognosis and predictive factors These patients have an indolent course with a long survival lime, even though patients with HCl -v do not typically respond to either IFN-a or purine nucleo- side analogs (oeoxvcotormvcln and cladribine) !l 850). Recent preliminary studies suggest that monoclonal antibody therapy (rituximab and anti-C022 immuno- toxin) is highly ellective 118501 In addi- tion. good clinical responses have been achieved with resolution of cytopenias after splenec tomy 118501. Splenic B-ceillymphoma/leukaemia, unclasslhable 193
  • Lymphoplasmacytic lymphoma SH. Swerdlow F. Berger SA Pilen N.L Harris E.S. Jaffe H. Stein Epldemk>logy LPL occurs in adults with a median age in the 60s and a slight male predominance 1581,23371. Etiology A familial predisposition may exist in up to 20% of patients with WM {29, 2267f. These patients are diagnosed at a younger age and with greater 8M in- volvement. Definition lymphoplasmacytic lymphoma (LPL) is a neoplasm of small 8 lymphocytes, plasma- cytoid lymphocytes, and plasma cells. usually involving bone marrow (8 M) and sometimes lymph nodes and spleen , which does not fulfill the criteria for any of the other small Bccell lymphoid neo- plasms that may also have ptasmacytlc differentiatiOn. Because the distinction be- tween lPL and one of mese other lym- phomas. especially some marginal zone lymphomas (MZL), is not always clear-cut. some cases may need 10be diagnosed as a small Bceujvmoboma with plasma- cvtrc differentiation and a d ifferential di- agnosisprovided.Although oftenassociated with a paraprotein usually of IgM type, it is not required for the diagnosis,Waldenstr6m macroglobulinemia (WM) is found in a significant subset of patients with LPL and is defined as LPL with 8M involvement and an IgM monoclonal gammopalhy 01 any concentration (16731. -. .. Clinica l features Most patients present with weakness and fatigue, usua lly related to anaemia. The majority of patients have an IgM serum paraprotein although othe rs may have a different paraprotein or no paraprotein at all. A minority have both 19M and IgG or other paraororens. Hyperviscosity occurs in up to 30% 01patients, The paraprotein may also have autoantibody or cryoglo- bulin activity, resulting in autoimmune phenomena or cryoglobulinemia (seen 10 up to -20% 01 patients with WM). Neuro- pathies occur in a minority 01 patients and may result from reactivity of the IgM para- protein with myelin sheath antigens, cryo- glo bulinemia or paraprotein deposition, Deposits of IgM may occur in the skin or the gastrointestinal tract, where they may cause diarrhoea Coagulopathies may be caused by IgM binding to clotting factors. platelets and fibrin. IgM paraproteins are not diagnostic 01 either LPL or WM as they can occur in patients with other lymphoid Hepatitis C virus (HCY) is associated with type II cryoglobulinemia and with LPL in some but not all series, perhaps related to geographic differences 1534. 1271, 1450A, 1597 , 1680, 1791 . 1932,21661. Some of the HCV-associated Iympho- plasmacytic proliferations even if mono- typic, are non-progressive and others may be more like chronic lymphocytic leu- kaemia (Cll) 11506. 23261. Treatment 01 these patients with anti-viral agents may lead to regression 01 the Iymphoplasma- cync proliferations {1434 . 21661. Apart from the role 01 HCY, mast cells may help drive the proliferation in LPL 122591. _.. fl9- 10.22 lym~ ~ ABone marrow biopsy shows a ~ infiltrate """ a PAS- po5ItrveOuk::her body(8fTOW). BThe ~smaq1ic I1fi1lraleis alsoseen inee asptalesme¥. Sites of involvement Most cases involve the BM and some, lymph nodes and other extranodal sites. About 15- 30% of patien ts with WM also have splenomegaly, hepatomegaly and/or adenopathy {5811· Peripheral blood (PB) may also be involved. 967113ICD-{) code, 194 Mature B-cell neoplasms
  • neoplasms or without an oven neoplasm. A minority of pa tients inJially present with an IgM-related disorder such as cryo- globulinemiaor IgM-monoclona1gamrT"l()o pathy of undetermined significance and only later develop an overt lPl 1370. 1230. 15241. -Bone manowand peripheral blood Bone marrow involvement is character- ized by a nodular. dlftuse and/or interstitial infiltrate usually composed predominantly of small lymphocytes admixed with variable rwroes of plasma cells and plasmacytoid tymphocytes 11672.16731 · Paratrabecular aggregates may also be present. In- creased mast cells are often present. Sim- ilar cells may be present in the PB. but the white blood count is typica lly lower than in ClL. Lymph nodesand other tissues In the most class ic cases that are usually associated with WM , lymph nod es show retention of normal architec tural features withdilated sinuses with PAS+ material and sometimes small port ions of residual ger- minal centres. There is a relatively mono- lonoos proliferation of small lymphocytes. plasma cells and plasmacytoid lympho- cytes with relatively few transformed cells. Dutcher bodies (PAS+ intranuclear pseudo- inclusions), increased mast cells and haemosiderin are othe r typical features. Other cases show greater architectural de- struction, may have a vaguely follicular grcmlh pattern. more prominent residual germinal centres, epithelioid histiocyte clusters and sometimes a much greater proportIOn of plasma cells ora more poIy- nn-phic appearance with more numerous transform