We studied the review article about How I investigate eosinophilia, which was published in the International Journal of Laboratory Hematology in August 2018. This paper has clearly and simply introduced how clinicians investigate eosinophilia. Hopefully, it can be helpful to everyone who interested in this field.
4. Introduction- impotence of eosinophil
• produce + store more than 30 cytokines, chemokines, and growth factors
→ vital to immune system response
• dysregulation can result in abnormal organ infiltration of the skin, heart,
and lung which can have life‐threatening consequences.
5. Background
• bone marrow: 1%‐6%
• peripheral blood: 3%‐5% (0.35‐0.5 × 109/L)
• Eosinophilia
mild
• up to
1.5 × 109/L
moderate
• 1.5‐5 × 109/L
severe
• >5 × 109/L
7. Diagnosis-histomorphology
• round to oval
• 10 to 15 μm in diameter
• nuclear: cytoplasmic ratio of 1:3
• refractile, coarse, orange‐red granules, uniform in size and
evenly fill the cytoplasm
• mature eosinophil: 80% two‐lobed nucleus with lobes of equal size and
ovoid shape
8. Eosinophil with atypical
nuclear segmentation
and cytoplasmic
vacuoles
Atypical eosinophil with
cytoplasmic vacuoles
Atypical eosinophil with
uneven granule
distribution and
cytoplasmic vacuoles
Circulating eosinophilic
myelocyte
Hypercellular marrow
with eosinophil
hyperplasia
Normal eosinophil
14. Case 1
• A 73-year-old man with history of prostate cancer
• Chief complaint: peripheral eosinophilia (AEC: 1700) for 3
months
14
No constitutional symptoms
No allergic disorders
No recent travel
No skin rashes
No lymphadenopathy
15. Ancillary test
15
Laboratory panel • Exclude allergic, infectious and autoimmune disorders
Peripheral blood
smear
• No circulating blasts, atypical lymphoid cells, or dysplastic
change
Bone marrow • 11.3% eosinophils with background maturing trilineage
hematopoiesis
Flow cytometry • No atypical immunophenotype
Karyotyping • A normal male karyotype
FISH • Negative for MDS
• No abnormality of PDGFRA
16. Reactive eosinophilia
• Eosinophilia is secondary in most cases.
• If not, evaluation for a primary eosinophilic disorder should be
performed.
16
17. Case 2
• A 58-year-old man without past medical history
• Chief complaint: fever and skin rash
17
Pruritic skin rash for 4 years, involving
bilateral extremities
Wax and wane
No recent travel
Bilateral axillary lymphadenopathy
Scaly rash
18. Ancillary test
18
Peripheral blood
smear
• Leukocytosis with eosinophilia (AEC: 4800)
• No circulating blasts, atypical lymphoid cells, or dysplastic
change
Bone marrow • Increased eosinophils with background maturing
trilineage hematopoiesis
Flow cytometry • A small CD3 and CD4 positiveT-cell population with
aberrant loss of CD7
Karyotyping • A normal male karyotype
FISH • Negative for MDS
• No abnormality of PDGFRA
19. Biopsy
• Skin
Fibrosis of papillary dermis
Psoriasiform changes
Hyperkeratosis with mild perivascular chronic inflammation with no
epidermotropism
• Lymph node
Dermatopathic lymphadenitis
19
20. Lymphocytic-variant hypereosinophilic
syndrome (L-HES)
• A clonal expansion of phenotypically aberrantT-cells with a
subsequent secondary eosinophilia
• Often present with cutaneous manifestations
• End-organ damage including cardiac and neurologic
involvement
• Development of overtT-cell neoplasms is well described.
20
21. Case 3
• A 74-year-old woman with history of allergic rhinitis and
transient ischemic attack
• Chief complaint: flu-like symptoms for 3 months
21
Fever, weakness, fatigue, night sweats, and
early satiety
No recent travel
Splenomegaly without lymphadenopathy
22. Ancillary
22
Cardiac workup • Restrictive cardiomegaly and mitral valve regurgitation
Peripheral blood
smear
• Leukoerythroblastic smear
• Neutrophilia, including a left shift to few blasts (7%)
• Eosinophilia (AEC: 16400) with atypical and immature
forms
Bone marrow • Hypercellular marrow
Flow cytometry • Myeloid predominant marrow with increased basophils
Karyotyping • A gain of chromosome 8 without t(9;22)
FISH • No abnormality of PDGFRA/PDGFRB/FGFR1
23. Chronic eosinophilic leukemia, not
otherwise specified (CEL, NOS)
• Myeloproliferative neoplasm: a clonal population of eosinophil
precursors, with blast < 20%
• Molecular genetic abnormality:TET2, ASXL1, DNMT3A
Can be seen in a minority of normal elderly people
• Must exclude other MPN and AML
No rearrangement of PDGFRA, PDGFRB, or FGFR1
No PCM1-JAK2 fusion
23
24. Idiopathic hypereosinophilic syndrome
(IHES)
• No increase in blasts
• End organ damage is present.
• Next-generation sequencing positive: similar clinical features
and bone marrow findings as CEL, NOS
24
25. Case 4
48‐year‐old man with a past history of diabetes and hypertension
Syncope, melena, and hematochezia for the past 2 months
Recent unintentional weight loss
No recent travel
Lab: eosinophilia and a leukocytosis
PE and CT: splenomegaly without
lymphadenopathy
26. Ancillary test
項目
Peripheral smear
• Myelophthisic smear
• Anemia, thrombocytopenia, and atypical eosinophilia
• Hypogranular forms
Bone marrow biopsy
• Hypercellular marrow with marked eosinophilia
• Megakaryocytic atypia including pyknotic forms and atypical
nuclear to cytoplasmic ratios
• No increase in blasts
• Diffuse marrow fibrosis
Flow cytometry No increase in blasts or other aberrancies
Karyotyping Normal male karyotype
FISH
• MDS and t(9;22) was negative
• CHIC2 deletion
• negative for abnormalities of PDGFRB and FGFR1
30. Myeloid and lymphoid neoplasms with eosinophilia
• Bone marrow evaluation:
Hypercellular marrow with granulocyte hyperplasia and eosinophilia
Often with accompanying fibrosis
• Karyotyping can identify abnormalities of PDGFRB, FGFR1, and
PCM1‐JAK2
• 4q12 deletion (CHIC2) is usually seen with abnormalities of PDGFRA
Requiring FISH
• Treatment with imatinib results in an excellent response
32. Chronic myeloid leukemia, BCR‐ABL1‐positive
• Myeloproliferative neoplasms
Major proliferative component with granulocytes
Philadelphia chromosome
• Peripheral absolute basophilia and eosinophilia with left shift
• Marrow: Small megakaryocytes with hypolobated nuclei
Megakaryocyte hyperplasia or myeloid hyperplasia
Identify the chromosomal translocation
34. Systemic mastocytosis
• Major criteria
Multifocal, dense infiltrates of mast cells (≥15 mast cells in aggregates)
detected in sections of bone marrow and/or other extracutaneous organs
• Minor criteria
In biopsy or bone marrow aspirate smears, >25% of the mast cells in the
infiltrate are spindle‐shaped or have atypical morphology
Detection of an activating point mutation at codon 816 of KIT in mast cell
Mast cells in bone marrow, blood or other extracutaneous organ express CD25
with/without CD2 in addition to normal mast cell markers
Serum total tryptase persistently exceeds 20 ng/mL (unless there is an
associated myeloid neoplasm, in which case this parameter is not valid)
35. Systemic mastocytosis
• SM and neoplasms associated with eosinophilia can present with
similar clinicopathologic features
• Via detection of dense aggregates of mast cells with IHC
CD117 and/or mast cell tryptase, CD25, CD2
• The mast cells in SM are almost always CD25 positive and CD2
positive in two thirds of cases
36. Acute myeloid leukemia
• inv(16)(p13.1q22) or t(16;16) (p13.1;q22);CBFB‐MYH11
may also present with eosinophilia
• Unlike most cases of AML
Blast count of 20% is not required to render this diagnosis
• Increased blasts with monocytic differentiation
• Necessitating FISH analysis for diagnosis
CBFB‐MYH11
• Harlequin cell
38. Classic Hodgkin lymphoma
• B‐cell neoplasm composed of mononuclear Hodgkin cells and classic
Reed‐Sternberg cells
• Typically associated with lymphadenopathy
• Not infrequently presents with reactive, non‐clonal peripheral
eosinophilia
Utilizing IHC to diagnose CHL
• Hodgkin cells have a unique morphology and immunophenotype,
typically expressing CD30, CD15, and PAX5 (reduced)
39. Chronic myelomonocytic leukemia
• Features of both a MPN and a MDS
• Absolute monocytosis
Can be associated with peripheral eosinophilia as well
• In patients with CMML and prominent eosinophilia, abnormalities of
PDGFRB must be excluded
41. Approach to eosinophilia
• A detail history and review of system
Duration of the eosinophilia as well as associated B‐symptoms including fever, night sweats,
and unintentional weight loss
Travel and medication history
Skin rashes, lymphadenopathy, cardiorespira‐ tory symptoms, and gastrointestinal symptoms
• Physical exam
Rash, lymphadenopathy, and organomegaly
• Lab
Chest radiography, echocardiogram, serum troponins, and oxygen saturation assess
end‐organ damage
CBC/DC, metabolic panel, tryptase, ESR, CRP,Vit B12, IgE levels and/or allergy testing, PB
smear
42. Approach to eosinophilia
• Review CBC parameters and PB smear
Isolated eosinophilia reactive eosinophilia
Cytopenias, basophilia, circulating blasts, and/ or leukoerythroblastosis genetic and
molecular test
PB smear
• Eosinophil morphology atypia including hypogranulation, atypical segmentation, mature
eosinophils with atypical basophilic granules
• Granulocyte morphology dysplasia such as abnormal nuclear segmentation or
hypogranular cytoplasm
• Red cell morphology anisocytosis and poikilocytosis, including dacrocytes and/or circulating
nucleated red blood cells
• Platelet morphology abnormal changes in platelet number, granularity, and size
43. Next steps to take
• Bone marrow biopsy detecting hematologic malignancies, metastatic disease,
and potentially infections
• Flow cytometry
Increased blasts (but <20%) CEL
abnormalT‐cell population L‐HES
aberrant expression of CD25 and/or CD2 on mast cells SM, but CD25 positivity can be
seen in mast cells of myeloid/lymphoid neoplasms with eosinophilia and rearrangement
of PDGFRA, PDGFRB, or FGFR1, or with PCM1‐JAK2
• Immunohistochemistry
Mast cell v.s SM CD117 and/or mast cell tryptase
CD30,CD15, and PAX5 Classic Hodgkin lymphoma
44. Next steps to take
• Cytogenetic testing (including FISH and RT-PCR)
4q12 (PDGFRA), 5q31‐q33 (PDGFRB), 8p11‐12 (FGFR1), or 9p24 (JAK2) myeloid and
lymphoid neoplasms with eosinophilia
PDGFRA abnormalitiesCEL
PDGFRB abnormalities CMML
AML with inv(16)(p13.1q22) or t(16;16)(p13.1;q22);CBFB‐MYH11
• Molecular test (NGS)
TET2,ASXL1, and DNMT3A CEL
ASXL1,TET2, EZH2, and SETBP1 a subset of IHES
46. Key problem areas
• Many reactive causes of eosinophilia exist History!!!!
• Cryptic cytogenetic abnormalities including, but not limited to inv(16) and CHIC2
deletions, that cannot be identified through conventional karyotyping require
FISH or RT‐PCR analysis
• Lack of consensus criteria for the diagnosis of L‐HES closely follow up as they
may develop overt lymphoma
• Clonal molecular genetic abnormalities (ie, TET2, ASXL1, and DNMT3A) seen in
CEL, NOS can also be seen in a minority of elderly people in the absence of a
hematologic malignancy
48. Reference
• Rebecca L. Larsen, Natasha M. Savage. How I investigate Eosinophilia. Int J Lab
Hem. 2019;41:153–161.
• GildaVarricchi, Maria Rosaria Galdiero, et al.. Eosinophils:The unsung heroes in
cancer? Oncoimmunolog. 2018; 7(2): e1393134.
• N. Savage, et al. Myeloid neoplasms associated with eosinophilia and
rearrangement of PDGFRA,PDGFRB, and FGFR1: a review. 2013; 35(2): 491-500
• Teresa Scordino. Morphologic variants of normal cells. 2016
• LeonardNaymagon, et al. Eosinophilia in acute myeloid leukemia: Overlooked and
underexamined. 2019; 36: 23-31
48
Editor's Notes
Eosinophils are terminally differentiated granulocytes
5 day maturation
18-24hr circulation
eosinophilic myelocyte: the earliest recognizable eosinophilic form on light microscopy
positivity can be seen in mast cells of myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1, or with PCM1‐JAK2
Many reactive causes of eosinophilia exist, requiring a thorough history and laboratory workup to exclude secondary causes of eosinophilia, which are much more common than primary eosinophilia.
• Cryptic cytogenetic abnormalities including, but not limited to inv(16) and CHIC2 deletions, that cannot be identified through conventional karyotyping require FISH or RT‐PCR analysis. A pathologist must be familiar with these cryptic aberrations and when to appropriately order FISH analysis.
• Lack of consensus criteria for the diagnosis of L‐HES may result in diagnostic confusion and clinician uncertainty. Moreover, close follow‐up of these patients is needed as they may develop overt lymphoma during follow‐up necessitating more aggressive therapy.
• Clonal molecular genetic abnormalities (ie, TET2, ASXL1, and DNMT3A) seen in CEL, NOS can also be seen in a minority of elderly people in the absence of a hematologic malignancy and must be evaluated in the clinical context