Chronic eosinophilic leukemia (CEL) can be diagnosed if certain findings are identified and alternative diagnoses have been excluded.


Key features:

(1) chronic eosinophilia

(2) exclusion of alternative diagnoses

(3) demonstration of a clonal proliferation of eosinophils


The primary distinction from the idiopathic hypereosinophilic syndrome is the presence of clonality in the eosinophils.


Features of chronic eosinophilia:

(1) absolute eosinophil count >= 1,500 per µL

(2) involve mature eosinophils

(3) duration >= 6 months



(1) reactive eosinophilia (allergy, parasites, autoimmune, etc.)

(2) neoplastic hematologic disorder with a reactive eosinophilia (T cell lymphoma, Hodgkin's disease, non-Hodgkin's lymphoma, ALL, mastocytosis)

(3) acute myeloid leukemia (AML)

(4) myelodysplastic disorders

(5) other myeloproliferative disorders (polycythemia, primary thrombocytosis, CML, myelofibrosis)

(6) aberrant T cell proliferations with abnormal cytokine production

(7) presence of Philadelphia chromosome and/or bcr-abl on cytogenetics

(8) blasts >= 20% of nucleated cells in the bone marrow


Demonstrate clonal proliferation - one or both of the following:

(1) clonal chromosomal abnormality

(2) other evidence of clonality


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