Chronic eosinophilic leukemia, NOS

ICD-O-1 Morphology

Effective 1978 - 1991

ICD-O-2 Morphology

Effective 1992 - 2000

ICD-O-3 Morphology

9964/3: Chronic eosinophilic leukemia, NOS
Effective 2001 and later


for cases diagnosed 1978 and later

Primary Site(s)

Primary site must be bone marrow (C421). Blood and bone marrow are always involved. Damage to a number of organs: heart, lungs, central nervous system (CNS), skin, gastrointestinal tract, spleen and liver are common.

Abstractor Notes

HES is traditionally treated with prednisone. Second-line drugs are interferon or hydroxyurea which induce remission in the majority of patients. If the prednisone. interferon and hydroxyurea are not effective, the patient may receive various chemotherapeutic drugs.

For more information, see the NCI website:

Diagnostic Confirmation

This histology can be determined by positive histology (including peripheral blood) with or without genetics and/or immunophenotyping. Review the Definitive Diagnostic Methods, Immunophenotyping and Genetics Data sections below, and the instructions in the Hematopoietic Manual for further guidance on assigning Diagnostic confirmation.


Not Applicable

Module Rule


Alternate Names

Chronic eosinophilic leukemia (and hypereosinophilic syndrome)
Hypereosinophilic (idiopathic) syndrome
Hypereosinophilic syndrome
Lymphocytic variant hypereosinophilic syndrome


Chronic eosinophilic leukemia (CEL) not otherwise specified (NOS), is a myeloproliferative neoplasm (MPN) in which an autonomous, clonal proliferation of eosinophil precursors results in persistently increased numbers of eosinophils in the peripheral blood, bone marrow, and peripheral tissues, with eosinophilia being the dominant hematological abnormality. Organ damage occurs as a result of leukemic infiltration, or of the release of cytokines, enzymes, or other proteins by the eosinophils.

For a diagnosis of CEL, NOS to be made, there should be evidence for clonality of myeloid cells or an increase in myeloblasts in the peripheral blood or bone marrow.

In many cases, it is impossible to prove clonality; in such cases, providing there is no increase in blast cells, the diagnosis of idiopathic hypereosinophilic syndrome (HES) is made.

The patient must have a sustained absolute eosinophil count greater than 500/pl that persists longer than six months. The physician excludes reactive eosinophilia, eosinophilia secondary to other neoplasms including T-cell neoplasia and other myeloid disorders. If above excludes peripheral blood blasts >2%, bone marrow >5% but <19%.

Diagnostic criteria for chronic eosinophilic leukemia, NOS
1. Eosinophilia (eosinophil count greater than or equal to 1.5 x 10 (9)/L)
2. WHO criteria for BCR-ABL1-positive chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, chronic neutrophilic leukemia, leukemia, chronic myelomonocytic leukemia and BCR-ABL1-negative atypical chronic myeloid leukemia ARE NOT MET.
3. No rearrangement of PDGFRA, PDGFRB or FGFR1, and no PCM1-JAK2.
4. Blast cells constitute less than 20% of the cells in the peripheral blood and bone marrow marrow, and inv(16)(p13.1q22), t(16;16)(p13.1;q22), t(8;21)(q22;q22.1) and other diagnostic features of acute myeloid leukemia are ABSENT.
5. There is a clonal cytogenetic or molecular genetic abnormality
OR blast cells account for greater than or equal to 2% of cells in the peripheral blood or greater than or equal to 5% in the bone marrow.

Definitive Diagnostic Methods

Bone marrow biopsy
Clinical diagnosis
Genetic testing
Peripheral blood smear

Genetics Data

Gain of chromosome 8
Loss of chromosome 7 or isochromosome 17q




Hematologic Transplant and/or Endocrine Procedures
Hormone therapy

Transformations from


Corresponding ICD-9 Codes

205.1 Chronic myeloid leukemia

Corresponding ICD-10 Codes

D47.1 Chronic myeloproliferative disease

Corresponding ICD-10-CM Codes (U.S. only)

D47.1 Chronic myeloproliferative disease (effective October 01, 2015 - September 30, 2020)
D72.110 Hypereosonophilic syndrome [HES] (effective October 01, 2020)
D72.111 Lymphocytic Variant Hypereosonophilic Syndrome [LHES] (effective October 01, 2020)
D72.118 Other Hypereosonophilic syndrome (effective October 01, 2020)
D72.119 Hypereosonophilic syndrome (effective October 01, 2020)

Signs and Symptoms

Angioedema (rapid swelling of the dermis)
Endomyocardial fibrosis
Muscle pains

Diagnostic Exams

Blood chemistry studies
Cytogenetic analysis
Peripheral blood smear

Progression and Transformation


Epidemiology and Mortality

Age: 40 years median age
Incidence: Rare neoplasm (true incidence unknown)
Sex: Male dominance
Survival: 5 year survival about 80% (variable)


Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds):
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition)
IARC: Lyon 2017
Section: Myeloproliferative neoplasms
Pages: 54-56

International Classification of Diseases for Oncology, Third Edition, Second Revision. Geneva: World Health Organization, 2020.
Section: ICD-O-3.2 (2020) Morphological Codes

National Cancer Institute
Section: General Information About Myeloproliferative Neoplasms