Juvenile myelomonocytic leukemia

ICD-O-1 Morphology

9863/3: Chronic myeloid leukemia, NOS
Effective 1978 - 1991

ICD-O-2 Morphology

9863/3: Chronic myeloid leukemia, NOS
Effective 1992 - 2000

ICD-O-3 Morphology

9946/3: Juvenile myelomonocytic leukemia
Effective 2001 and later


for cases diagnosed 1978 and later

Primary Site(s)

Primary site must be bone marrow (C421)

Abstractor Notes

The peripheral blood and bone marrow are always involved; proliferation of the granulocytic and monocytic lineages. Blasts plus promonocytes account for <20% of PB and BM. Leukemic infiltrates are common in the skin.

The physician will test to confirm that the Philadelphia chromosome and the BCR-ABL1 fusion gene are absent.

Although JMML rarely transforms into acute leukemia, it is a rapidly-fatal disease for most children if left untreated.

In the absence of effective treatment most children die from organ failure, such as respiratory failure, due to leukemic infiltration. Stem cell transplant can cure about half of the patients.

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

Juvenile chronic myelomonocytic leukemia


A rare form of childhood leukemia in which cancer cells often spread into tissues such as the skin, lung and intestines.

JMML is a clonal hematopoietic disorder of childhood that is characterized by proliferation principally of the granulocytic and monocytic lineages. Erythroid and megakaryocytic abnormalities frequently present, in keeping with evidence that JMML arises from a BM stem cell with multilineage potential in the myeloid series.

Definitive Diagnostic Methods

Bone marrow biopsy
Genetic testing
Peripheral blood smear

Genetics Data

Monosomy 7




Hematologic Transplant and/or Endocrine Procedures
Radiation therapy

Transformations from


Corresponding ICD-9 Codes

206.1 Chronic monocytic leukemia

Corresponding ICD-10 Codes

C93.1 Chronic monocytic leukemia

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

C93.3 Juvenile myelomonocytic leukemia (effective October 01, 2015)

Signs and Symptoms

Easy bruising or bleeding
Enlarged tonsils
Frequent infections
Pain or a feeling of fullness below the ribs
Pale skin
Shortness of breath
Skin rashes

Diagnostic Exams

Blood chemistry studies
Cytogenetic analysis
Peripheral blood smear

Progression and Transformation

Rarely transforms to acute myeloid leukemia

Epidemiology and Mortality

Age: 0-14 years (75% of cases <3 years of age)
Incidence: 1.3 per million children 0-14 years of age per year
Sex: male predominance
Survival: 1 year (without stem cell transplant). Cure is possible for patients who have a stem cell transplant


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: Myelodysplastic/myeloproliferative neoplasms
Pages: 89-92

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 Myelodysplastic/ Myeloproliferative Neoplasms (MDS/MPN)