Leukemia
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Leukemias are malignant diseases of the bone marrow characterized by the abnormal proliferation of white blood cells. The document discusses the classification, pathogenesis, epidemiology, clinical features, diagnosis and prognosis of various types of leukemias. It describes the key subtypes of acute and chronic leukemias, focusing on chronic myeloid leukemia, which results from a genetic translocation forming the Philadelphia chromosome and the constitutively active BCR-ABL fusion oncogene that drives uncontrolled myeloid cell growth.
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Leukemia
- 2. Leukaemias Definition • Leukaemia is a malignant disease of the haemopoietic tissue,characterized by the replacement of normal bone marrow elements with abnormal blood cells. • Leukaemic cells are frequently present in the peripheral blood, commonly invade spleen, liver and lymph nodes and other tissues of the body, eg testes, brain, meninges and skin
- 3. Classification of Leukaemias Acute leukaemia • Acute lymphoblastic leukaemia • Acute myeloid leukaemia Chronic leukaemia • Chronic myeloid leukaemia • Chronic lymphocytic leukaemia
- 4. Classification of leukaemias • Other chronic lymphoid leukaemias Hairy cell leukaemias Prolymphocytic leukaemia Lymphoma/leukaemia • ‘Pre - leukaemia’ - myelodysplastic syndrome
- 5. Pathogenesis of Acute leukaemia • Origin of leukaemia at the genetic level appears to be related to mutations and altered expression of oncogenes and tumor suppressor genes • Oncogenes regulate cell proliferation and differentiation • Abnormal oncogene or tumour suppressor gene expression induced by translocation and genetic fusion or mutation results in unregulated cellular proliferation
- 6. Pathogenesis of Acute leukaemia • Genetic alteration occurs within a single abnormal stem cell or progenitor cell in the marrow. • Successive generation of cells derived by mitosis from the original abnormal cell gives rise to a clonal population, which, when sufficiently large, causes clinically apparent disease
- 7. Pathogenesis of Acute leukaemia • Acute leukaemia, blasts cells fail to differentiate normally, further divisions continue, results in accumulation, replacement of normal cells by lymphoblasts or myeloblasts – bone marrow failure • Clinical condition correlate with total number of leukaemic cells in the body. • When 60% or more of total marrow cells – peripheral blood involvement, liver, spleen and lymph nodes are infiltrated.
- 8. Epidemiologic aspects of leukaemia • Host factors 1. Heredity • Appears not to be inherited but increased predisposition in some individuals. Family members of leukaemia pts – possible shared environment Identical twin –shared placental circulation (possible in utero exposures)
- 9. Epidemiologic aspects of leukaemia 2. Congenital chromosomal abnormalities Disorders with genetic abnormalities predispose to acute leukemias : - Down’s syndrome 10 to 20 fold increase of acute leukaemia. AML 1 gene identified in chromosome 21 - Fanconi’s anaemia (AML) - Ataxia telaniectasia (ALL,NHL)
- 10. Epidemiologic aspects of leukaemia 3. Immunodeficiency • Hereditary immunodeficiency states, high incidence of lymphoproliferative disorder 4. Chronic marrow dysfunction MDS, myeloproliferative disorders, aplastic anaemia, increased risk of acute leukaemia transformation
- 11. Epidemiologic aspects of leukaemia • Environmental factors 1. Ionizing radiation Exposure associated with develoment of acute and chronic leukaemia Illustrated in populations exposed to nuclear weapons in Hiroshima and Nagasaki 2. Chemicals and drugs Benzene – most frequently documented chemical toxin Alkylating drugs – pts on combined chemoradiotherapy for Hodgkin’s disease Chemotherapy – 10 % - 20% of all AML, secondary AML
- 12. Epidemiologic aspects of leukaemia 3. Viruses Human T cell leukaemia/lymphoma virus Implicated causative agent for adult T cell leukaemia/lymphoma Epstein Barr virus linked to African Burkitt lymphoma – high grade B cell lymphoma
- 13. Incidence • Acute leukaemia comprises > 50% of leukaemia seen in clinical practice • ALL, common form in children, peak 3-4 yrs falling off by 10 yrs • AML occurs in all age groups common type in adults, elderly, only 10 -15% of leukaemia in childhood
- 14. Incidence • Chronic leukaemias • Generally disease of adults • CLL extremely rare in children, unusual before 40 yrs • CML seen at any age, peak incidence 30- 50 yrs, rare in children • Distinct juvenile variant (jCML) in children
- 15. Comparison of Acute and Chronic leukaemia Acute Chronic • Age All ages Adults • Clinical onset sudden insidious • Course <6 months 2-6 yr • Leukaemic cells immature mature • Anaemia mild-severe mild • Thrombocytopenia mild-severe mild • TWBC variable increase • Organomegaly mild prominent
- 16. Acute leukaemia • Acute leukaemia is defined as the presence of >30% blasts in the bone marrow at clinical presentation. • Subdivided into two types on the basis of blasts. • Acute lymphoblastic leukaemia • Acute myeloid leukaemia
- 17. Clinical features of acute leukaemia Pathogenesis Clinical features • Bone marrow failure • Anaemia Fatigue, malaise,pallor • Thrombocytopenia Bruising, bleeding • Neutropenia Fever, infection
- 18. Clinical features of acute leukaemia Organ infiltration • Marrow expansion Bone or joint pain • Spleen Splenomegaly • Liver Hepatomegaly • Lymph nodes Lymphadenopathy • CNS CNS symptoms • Gums, mouth gum hypertropy, oral lesions
- 19. CLASSIFICATION • Morphology – French-American-British (FAB) classification – WHO classification • Immunophenotype- ALL Importance of classification – Determine mode of treatment – Prognostic value
- 20. FRENCH-AMERICAN-BRITISH (FAB) CLASSIFICATION ACUTE LEUKEMIA Acute myeloid leukemia Acute lymphoblastic leukemia M0 undifferentiated M1 without maturation M2 with granulocytic maturation M3 acute promyelocytic M4 granulocytic and monocytic maturation M5 monoblastic (M5a) or monocytic (M5b) M6 erythroleukemia M7 megakaryoblastic L1 L2 L3 (Burkitt)
- 21. FAB classification • Acute lymphoblastic leukaemia subdivided • Based on morphology and cytochemistry • L1 • L2 • L3
- 22. ALL- L1 • Blasts are small • Homogenous • High N/C ratio • scanty cytoplasm
- 23. ALL- L2 • Blasts are larger • heterogenous • Low N/C ratio • More abundant cytoplasm
- 24. ALL- L3 • Blasts are deeply basophilic • Vacuolated cytoplasm
- 25. FAB classification AML • M0 – undifferentiated • M1 – without maturation • M2 – with granulocytic maturation • M3 – acute promyelocytic leukaemia • M4 – granulocytic and monocytic maturation • M5 – monoblastic (M5a) • monocytic (M5b) • M6 – erythroleukaemia • M7 - megakaryoblastic
- 26. Myeloblast with auer rod
- 27. FAB classification • AML M0
- 28. AML-M1 • Blast cells have few azurophilic granules • May have auer rods
- 29. AML –M2 • Multiple granules • May have Auer rods • With granulocytic differentiation
- 30. AML- M3 • Abnormal promyelocytes • Prominent granules • Multiple Auer rods
- 31. AML- M4 • Have monocytoid differentiation • > 20% or more is monocytoid cells
- 32. AML- M5a • Monoblastic • > 80% of blasts are monoblasts
- 33. AML- M5b • Monocytic • < 80% of blasts are monoblasts
- 34. AML- M6 • Predominance of erythroblast • Dyserythropoiesis
- 35. AML- M7 • Megakaryoblast with cytoplasmic blebs
- 36. FAB M3 and M 4 /M 5 features FAB M3 • Bleeding tendency • DIVC • Pancytopenia • FAB M 4 / M 5 • Gum hypertrophy and infitration • Skin involvement • CNS disease • Granulocytic sarcoma – isolated mass of leukaemia blasts
- 37. Laboratory and Radiographic Work-up: • CBC with manual differential • Uric Acid level • Clotting studies (PT, PTT, D-dimer, fibrinogen) • Bone marrow aspirate and biopsy • Chest xray • Echocardiogram
- 38. Diagnosis Of Acute Leukemia • Demonstrate > 30% blasts in the bone marrow. • Diagnosis of acute leukemia is based on the following: 1.Morphology of the blasts 2.Cytochemistry( MPO,Sudan black- B,NSS, PAS). 3.Immunophenotyping 4.Cytogenetics
- 39. LABORATORY DIAGNOSIS • Complete blood count – Normochromic normocytic anemia – Thrombocytopenia – WBC- variable • Peripheral blood film – Blasts • Bone marrow examination – Hypercellular – > 30% leukemic blasts • Cytochemistry – Myeloperoxidase – Sudan black – Non-specific esterase – Periodic acid-Schiff – Acid phosphatase • Flow cytometry – Myeloid and/or lymphoid markers • Genetic analysis
- 40. • Others – Lumbar puncture- leukemic cells – Uric acid, LDH, Calcium – may be raised – Renal & liver function test- baseline – X-ray- lytic bone lesion, enlarge mediastinum (T-ALL)
- 41. Morphology • Majority of leukemias at most of the centers world over are diagnosed by morphology and cytochemistry • Blasts cells are large cells with: a)High N:C ratio b)Nucleus is large with open chromatin c)Nucleoli 1- 5 d)Thin rim to moderate amount of cytoplsm
- 42. Cytochemistry • Bone marrow smears are stained to determine specific enzymes or other proteins produced by cellular organelles.
- 43. Cytochemistry ALL AML Myeloperoxidase _ +, auer rods Sudan black _ +, auer rods Periodic acid schiff + + M6 (coarse granular) (fine blocks) Nonspecific esterase _ + M4,M5 Acid phosphatase + T ALL +M6 (golgi staining) (diffuse)
- 44. Periodic acid- Schiff Coarse block positivity- ALL Fine blocks – M6
- 45. Sudan black • Black staining in cytoplasm
- 46. Non-specific esterase • Positive in M4, M5 • Monoblast cytoplasm – Orange staining • Myeloblast cytoplasm – Blue staining
- 47. Immunological classification AML ALL Marker precursor B T Myeloid CD 13 + - - CD 33 + - - Glycophorin + M 6 - - Platelet antigen CD41 +M 7 - - Myeloperoxidase +M 0 - -
- 48. Immunological classification AML ALL Marker precursor B T B lineage ALL CD 19 - + - cCD22 - +or- - CD 10 - + -
- 49. Immunological classification AML ALL Marker precursor B T T lineage CD 7 - - + cCD3 - - + TdT - + +
- 50. Cytogenetics • Essential component in newly diagnosed leukaemic pts • Major role in diagnosis • Subclassification • Selection of appropriate therapy • Monitering effects of therapy
- 51. Cytogenetics Chromosomal abnormalities associated with distinct types of leukaemia • t (15;17) unique to APML (FAB M3) • Inv (16) AMML with abnormal eosinophilia (M4Eo) • t (9;22) Ph chromosome in CML , ALL
- 52. AML- M2 AML- M4
- 53. AML-M3 • blocks differentiation at the promyelocyte stage • All-trans retinoic acid (ATRA) allow them to differentiate and to apoptose
- 54. ALL
- 55. Prognostic value good poor AML t (15;17) – M3 t (8;21) – M2 Inv (16) –M4 Del of chr 5 or 7 t (6;9) 11q23 ALL Ph+ 11q23
- 56. Molecular genetics • Primarily used for confirmation of suspected chromosomal abnormality not detected by conventional cytogenetics. • Monitoring minimal residual disease following therapy Hand out – molecular correlation of common chromosomal abnormalities in acute leukaemia
- 57. Prognosis in ALL Good Poor • WBC Low High > 50,000 • Sex Girls Boys • Immunophenotype c-ALL B ALL • Age Child Infants<2 yrs, adults • Cytogenetics Normal Ph+, 11q23 or hyperdiploidy
- 58. Prognosis in ALL Good Bad • Time to clear blasts <1 week >1 week from blood • Time to remission <4 weeks >4 weeks • CNS disease at presentation Absent Present • Minimal residual disease negative at still positive 1-3 months 3-6 months
- 59. Prognosis in AML Good Bad • Cytogenetics t(15:17) delection of chromosome t(8;21) 5or7 inv (16) 11q23 t(6;9) • Bone marrow response <5% blasts >20% blasts after to remission induction after first course first course • Age < 60 yrs >60 yrs
- 61. Chronic Myeloid Leukaemia •Disorder proliferation of haemopoietic stem cells •Incidence increases with age – Median age: 40 - 60 – Youngest so far – 12 years old •Slightly higher incidence in males – Male-to-female ratio—1.3:1 •Cause – Unknown – Slightly increased risk following high dose irradiation: Japanese atomic bomb survivor •Median survival: 5 years
- 62. Melo. Blood. 1996;88:2375. Pasternak et al. J Cancer Res Clin Oncol. 1998;124:643. The Ph Chromosome and the bcr-abl Gene: The t(9;22) Translocation FUSION PROTEIN WITH CONSTITUTIVE TYROSINE KINASE ACTIVITY bcr-abl bcr Philadelphia Chromosome (or 22q-) Chromosome 9 q+ abl Chromosome 9 Chromosome 22
- 63. Pathogenesis •Translocation of genetic material between chromosom 9 and 22 results in fusion gene: bcr – abl (Philadelphia chromososom) • BCR-ABL fusion gene (M-BCR) encodes a protein of molecular weight 210 kDa that has greater tyrosine kinase activity than the normal ABL gene product.
- 64. The Ph Chromosome and the bcr-abl Gene: bcr-abl Gene Structure p210Bcr-Abl c-abl1 p185Bcr-Abl2-11 2-11 Chromosome 9 c-bcr Chromosome 22 2-11 Exon on chromosome 22 Exon on chromosome 9 Introns CML breakpoints Melo. Blood. 1996;88:2375. Pasternak et al. J Cancer Res Clin Oncol. 1998;124:643.
- 65. Prevalence of the Philadelphia Chromosome in Leukemias Faderl et al. Oncology (Huntingt). 1999;13:169. %ofPh+patients 0 20 40 60 80 100 CML ALL (adult) ALL (pediatric) AML 95 30 5 2
- 66. Clinical Presentation • Asymptomatic in ~50% of cases – Incidental finding of leucocytosis • Common symptoms – Fatigue – Weight loss/anorexia – Abdominal fullness • Common signs – Palpable splenomegaly • Common laboratory findings – Abnormal differential WCC – Leukocytosis – Thrombocytosis – Anemia – Basophilia
- 67. CML•3 clinical stages – Chronic phase – Accelerated phase – Blastic phase •40% patient: disease progress from chronic to blastic phase •Blast transformation occur: 3 – 5 years
- 68. Laboratory investigations in CML • FBC/FBP – anaemia, leucocytosis, immature granulocytes, basophilia, thrombocytosis, occasional blast (chronic phase) •NAP score – low •LDH – high •BMAT – Hypercellular marrow with granulocytic hyperplasia. Blasts not more than 10%. •Cytogenetic – Philadelphia chromosome •Molecular analysis – FISH/RT-PCR
- 71. Hematologic Parameters by Phase of CML Parameter Chronic Accelerated Blastic WBC count (/L) High High High Blasts (%) 1-10 ≥10, < 20 ≥30 Basophils (%) ↑ ≥20 Basophilia Platelets ↑ or normal ↓ or ↑ ↓ Bone marrow Myeloid hyperplasia Blasts+++
Editor's Notes
- A gene that contributes to the production of a cancer. Oncogenes are generally mutated forms of normal cellular genes (proto-oncogenes). A gene capable, when activated, of transforming a cell. Oncogenes are found in the oncogenically activated state in retroviruses and transformed cells and in their normal non-oncogenically activated state in non-transformed cells in which they are called proto-oncogenes.
- the fact or condition of being genetically identical, as to a parent, sibling, or other biological source
- MRD stands for Minimal Residual Disease. It is a term that simply put means that they detect leukemia cells with a much greater sensitivity than they did in the early days of childhood leukemia treatment. Instead of looking at 100 cells and finding 1 leukemia cell, they can now look at 10,000 cells and find 1 leukemia cell
- Globally, CML has an incidence of 1 to 2 cases per 100,000 population and is responsible for 15% to 20% of all adult leukemia. The median age at presentation is 53 years, with a median range of 45 to 55 years. The incidence of CML increases with age; up to 30% of patients are 60 years of age or older at presentation, which may influence the selection of treatment options in this population. CML is less common in children, with approximately 10% of patients less than 20 years of age. CML occurs somewhat more frequently in males, with a male-to-female ratio of 1.3:1. Approximately 50% of patients are asymptomatic at diagnosis, with CML discovered through routine laboratory blood tests. Eighty-five percent of patients are diagnosed during the chronic phase of disease.
- The Ph chromosome is the result of a reciprocal translocation, t(9;22)(q34;q11), between the long arms of chromosomes 9 and 22. A segment of the abl gene (Abelson mouse leukemia proto-oncogene) on chromosome 9q34 coding for a nonreceptor tyrosine kinase is translocated to the bcr gene (breakpoint cluster region) on chromosome 22q11 to form an abnormal hybrid bcr-abl gene. The bcr-abl gene is transcribed into a hybrid messenger RNA; the translation product of this RNA is an abnormal fusion protein tyrosine kinase. The Ph chromosome was first described in 1960 as a shortened chromosome 22 present in myeloid cells from patients with CML. This was the first report of a human cancer associated with a specific genetic abnormality. Ninety-five percent of patients with CML have the Ph chromosome—hence, this chromosome is the hallmark of CML. The Ph chromosome can be detected in BM cells in metaphase by standard cytogenetic techniques. The Ph chromosome is present in all myeloid cell lineages, including erythrocytes, granulocytes, monocytes, and megakaryocytes, as well as some cells of lymphocytic lineage, indicating that malignant transformation to CML originates at the stem cell level. Irradiated mice that received BM infected with a retrovirus carrying the p210 Bcr-Abl kinase encoded by the Ph chromosome developed hematologic malignancies, including a myoproliferative disease similar to chronic phase CML.
- Globally, CML has an incidence of 1 to 2 cases per 100,000 population and is responsible for 15% to 20% of all adult leukemia. The median age at presentation is 53 years, with a median range of 45 to 55 years. The incidence of CML increases with age; up to 30% of patients are 60 years of age or older at presentation, which may influence the selection of treatment options in this population. CML is less common in children, with approximately 10% of patients less than 20 years of age. CML occurs somewhat more frequently in males, with a male-to-female ratio of 1.3:1. Approximately 50% of patients are asymptomatic at diagnosis, with CML discovered through routine laboratory blood tests. Eighty-five percent of patients are diagnosed during the chronic phase of disease.
- The abl gene, which spans exons 2 through 11 on chromosome 9, encodes native tyrosine kinase (145 kDa). Wild-type Abl (or c-Abl) kinase has normal signal transduction activity in a nonmalignant cell. During the translocation between chromosomes 9 and 22, the breakpoint in the c-abl gene fragment usually occurs 5&apos; to exon 2. In contrast, the breakpoint site on the bcr gene may vary (eg, between exons b1 and b2, b3, or b4), resulting in fusion gene products of varying lengths, which in turn code for fusion protein tyrosine kinases of different molecular masses: 185/190 kDa, 210 kDa, and 230 kDa (not shown), all with tyrosine kinase activity. The Bcr portion of the protein interferes with the regulatory component of the c-Abl kinase activity, resulting in kinase activity that is constitutively activated. The p210Bcr-Abl fusion protein tyrosine kinase is expressed primarily in CML, the p190Bcr-Abl primarily in Ph+ ALL, and the p230Bcr-Abl in a subset of patients with CML.
- The Ph chromosome is also seen in leukemias other than CML. About 5% of childhood ALL, 15% to 30% of adult ALL, and 2% of cases of AML are Ph+. In some patients with CML, the Ph chromosome may not be detectable by cytogenetic analysis. For those cases, molecular techniques such as Southern blotting, fluorescence in situ hybridization (FISH), and reverse transcriptase polymerase chain reaction (RT-PCR) can be used to detect the presence of the bcr-abl gene.
- The most common symptoms at presentation in the chronic phase of CML include fatigue, weight loss, abdominal fullness, and night sweats. In 50% of cases, the clinical presentation is asymptomatic. Physical examination shows palpable splenomegaly in more than 50% of patients. Typical laboratory results include leukocytosis with an abnormal differential, anemia, basophilia, and thrombocytosis.
- CML is a clonal proliferation of a malignant hematopoietic progenitor cell. The disease has been studied extensively and is characterized by defined clinical stages and prognostic factors. The efficacy and safety outcomes from a number of treatment regimens are well documented. In 1961, an aberrant chromosome that is unique to this disease was identified in bone marrow (BM) cells from patients with CML. Termed the Philadelphia (Ph) chromosome, it is a shortened chromosome 22 resulting from a reciprocal translocation, t(9;22)(q34;q11), between the long arms of chromosomes 9 and 22. The Ph chromosome, which is present in 95% of patients with CML, produces an abnormal, constitutively activated Bcr-Abl tyrosine kinase that is linked to malignant transformation. Thus, the Bcr-Abl kinase is an attractive target for rational drug design.
- CML is a clonal proliferation of a malignant hematopoietic progenitor cell. The disease has been studied extensively and is characterized by defined clinical stages and prognostic factors. The efficacy and safety outcomes from a number of treatment regimens are well documented. In 1961, an aberrant chromosome that is unique to this disease was identified in bone marrow (BM) cells from patients with CML. Termed the Philadelphia (Ph) chromosome, it is a shortened chromosome 22 resulting from a reciprocal translocation, t(9;22)(q34;q11), between the long arms of chromosomes 9 and 22. The Ph chromosome, which is present in 95% of patients with CML, produces an abnormal, constitutively activated Bcr-Abl tyrosine kinase that is linked to malignant transformation. Thus, the Bcr-Abl kinase is an attractive target for rational drug design.
- Diagnostic tests are critical for confirming the presence of CML and staging the disease to determine potential treatment options. In a peripheral complete blood count with differential, the white blood cell (WBC) count is typically 20×109/L and may increase as the disease progresses. Increased numbers of granulocytes at all stages of maturation account for many of the elevated WBC counts. The increase in peripheral blast counts is characteristic as the disease enters the accelerated phase and blastic phase, at which time the disease resembles acute leukemia. Although elevated platelets are frequently seen in the chronic phase, thrombocytopenia may signal the onset of advanced disease. Progressive anemia and basophilia are also characteristic of the advanced stages of CML, although lymphocyte and monocyte counts may remain relatively normal. In BM aspirates and biopsy samples, the marrow is hypercellular with excessive myeloid hyperplasia and a shift to more immature myeloid forms and blasts; the myeloid-to-erythroid ratio is elevated to 10:1 to 30:1 (normal, 2:1 to 5:1). Eosinophils, basophils, and megakaryocytes are increased in number and may appear dysplastic. Cytogenetic analysis shows the presence of the Ph chromosome in 95% of patients; however, with advanced disease, additional karyotypic abnormalities may develop.The detection of bcr-abl RNA transcripts by the sensitive polymerase chain reaction is also used.