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Chronic Myeloid Neoplasms

Myeloproliferative neoplasms (MPN)

Chronic eosinophilic leukemia (CEL) not otherwise categorized

Reviewer: Nikhil Sangle, M.D., University of Utah & ARUP Laboratories (see Reviewers page)
Revised: 4 August 2011, last major update August 2011
Copyright: (c) 2001-2011, PathologyOutlines.com, Inc.


● “Not otherwise categorized” because there are no rearrangements of PDGFRA, PDGFRB or FGFR1 genes
● Much rarer than reactive eosinophilia
Note: published cases without molecular analysis may be chronic eosinophilic leukemia, hypereosinophilic syndrome, myeloid neoplasms associated with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR1 or mast cell disease (with eosinophilia)
● Usually multiorgan disease (heart, lungs, CNS, GI tract, skin) due to eosinophil infiltration and release of cytokines and other substances from eosinophil granules


● Bone marrow examination with tryptase (to identify mast cells), T cell clonal studies, immunohistochemistry, cytogenetic studies and molecular studies to detect (and rule out) PDGFRA, PDGFRB or FGFR1 rearrangements

Diagnostic criteria:
● ≥1.5 x 109/L peripheral blood eosinophils (persistent)
● Either peripheral blood blasts > 2%, bone marrow blasts > 5% or abnormal cytogenetics; exclusion of secondary eosinophilia
● Exclusion of other acute or chronic myeloid neoplasms
● No evidence of phenotypically abnormal or clonal T lymphocytes
● No evidence of PDFGRA, PDGFRB or FGFR1 rearrangements
Note: WHO 2001 included criterion of evidence of clonality (Blood 2004;104:3836), which is not explicitly indicated in WHO 2008

Diagnostic algorithm (WHO 2008)

Case reports

● Liver infiltration resembling Budd-Chiari syndrome (Rinsho Ketsueki 2007;48:505)


● Possibly interferon for patients with JAK2 617F mutations (Haematologica 2007;92:e118)

Micro description

Peripheral blood: mostly mature eosinophils, occasionally immature forms; no/occasionally mildly dysplastic forms
● May have increased neutrophil count
Bone marrow: hypercellular marrow with marked increased in eosinophil precursors
● Normal erythroid, neutrophil and megakaryocyte maturation
● Normal or mildly increased myeloblasts
● Variable dysplastic changes

Micro images

*in cases before molecular studies were indicated

Peripheral blood:

A: Six eosinophils and neutrophil; B/C/D: bone marrow smear shows replacement by eosinophils, predominately eosinophilic myelocytes, metamyelocytes and band eosinophils with occasional segmented (bilobed) eosinophilic cells

Bone marrow biopsy:

Markedly hypercellular due to eosinophils and precursors, megakaryocytes are markedly reduced, reticulin fibers are increased

Markedly fibrotic marrow #1 (therapy was unsuccessful); #2 shows blasts and immature cells throughout fibrotic tissue

Bone marrow smear:

Numerous eosinophilic myelocytes and eosinophils

Cytogenetics description

● Usually no abnormalities

EM images

Abnormal eosinophil with decreased granules, most granules are homogeneous (normal eosinophilic granules have dense core surrounded by less dense capsule)

Differential diagnosis

● Reactive eosinophilia due to parasitic infections, allergies, pulmonary diseases such as Loeffler’s syndrome, collagen vascular disorders; T-cell lymphoma or Hodgkin lymphoma; acute or chronic myeloid neoplasms; mast cell disease

End of Chronic Myeloid Neoplasms > Myeloproliferative neoplasms (MPN) > Chronic eosinophilic leukemia (CEL) not otherwise categorized

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