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ICD-O-3 Morphology
9946/3: Juvenile myelomonocytic leukemia
Effective
2001 and later
Reportable
for cases diagnosed
1978 and later
Primary Site(s)
C421
Primary site must be bone marrow (C421)
Coding Manual:
Hematopoietic Coding Manual (PDF)
Abstractor Notes
Juvenile myelomonocytic leukemia (JMML) is part of the Myeloproliferative neoplasms (MPN) lineage table in the WHO 5th edition of Hematolymphoid Tumors. (See Appendix B in the Hematopoietic Manual, Table B2)
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.
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.
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.
Module Rule
None
Alternate Names
JMML-like disorders in children with Noonan syndrome (NS)
JMML in children with CBL syndrome
JMML in neurofibromatosis type 1 (NF1)
Juvenile chronic myelomonocytic leukemia
KRAS-mutated JMML
NRAS-mutated JMML
PTPN11-mutated JMML
Definition
"Juvenile myelomonocytic leukemia (JMML) is a RAS pathway activation–driven myeloproliferative neoplasm of early childhood leading to peripheral granulocytosis and monocytosis, with frequent organ infiltration." (WHO 5th edition).
The bone marrow and peripheral blood are always involved, and leukemic infiltrates are almost always seen in the spleen. Leukemic infiltrates may also occur in the liver, lymph nodes, lung, and gastrointestinal tract.
Approximately 25% of cases develop in the context of a genetic syndrome, such as neurofibromatosis type 1, Noonan syndrome, germline CBL syndrome.
The complete blood count shows leukocytosis, thrombocytopenia, and anemia.
The bone marrow and peripheral blood are always involved, and leukemic infiltrates are almost always seen in the spleen. Leukemic infiltrates may also occur in the liver, lymph nodes, lung, and gastrointestinal tract.
Approximately 25% of cases develop in the context of a genetic syndrome, such as neurofibromatosis type 1, Noonan syndrome, germline CBL syndrome.
The complete blood count shows leukocytosis, thrombocytopenia, and anemia.
Definitive Diagnostic Methods
Cytogenetics
Genetic testing
Immunohistochemistry
Immunophenotyping
Genetics Data
Immunophenotyping
Aberrant blast population expressing CD7 and decreased levels of CD13 and CD33
Abnormal maturation pattern of granulocytes can be detected using CD13 and CD16
HAL-DR expression on monocytes is decreased
Treatments
Chemotherapy
Hematologic Transplant and/or Endocrine Procedures
Radiation therapy
Surgery
Transformations to
Transformations from
None
Same Primaries
Corresponding ICD-10 Codes (Cause of Death codes only)
C93.1 Chronic monocytic leukemia
Corresponding ICD-10-CM Codes (U.S. only)
C93.3 Juvenile myelomonocytic leukemia (effective October 01, 2015 - September 30, 2024)
C93.10 Juvenile myelomonocytic leukemia, not having achieved remission (effective October 01, 2024)
C93.11 Juvenile myelomonocytic leukemia, in remission (effective October 01, 2024)
C93.12 Juvenile myelomonocytic leukemia, in relapse (effective October 01, 2024)
Signs and Symptoms
Abdominal distention
Bleeding
Easy bruising or bleeding
Enlarged tonsils
Fatigue
Fever
Frequent infections (usually respiratory)
Gastrointestinal symptoms
Hepatosplenomegaly
Infection
Lymphadenopathy
Pain or a feeling of fullness below the ribs
Pallor
Pleomorphic skin lesions
Shortness of breath
Skin rashes
Diagnostic Exams
Bone marrow aspiration and biopsy
CT (CAT) Scan
Cytogenetic analysis
Flow cytometry
Immunophenotyping
Lumbar puncture
Molecular analysis
Peripheral blood smear/flow cytometry
Physical exam and history
Epidemiology and Mortality
Age: 0-14 years (95% of cases <4 years of age)
Incidence: 1.2 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
Sources
WHO Classification of Tumours Editorial Board. Haematolymphoid tumours. Lyon (France): International Agency for Research on Cancer; 2024. (WHO classification of tumours series, 5th ed.; vol. 11). https://publications.iarc.who.int/637.
Section: Myeloproliferative neoplasms
Pages: Part A: 53-56
Section: Myeloproliferative neoplasms
Pages: Part A: 53-56
International Classification of Diseases for Oncology, 3rd edition (including revisions). Geneva: World Health Organization, 2001, 2011, 2020.
Section: ICD-O-3.2 (2020) Morphological Codes
Pages: http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577
Section: ICD-O-3.2 (2020) Morphological Codes
Pages: http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577
PDQ® Adult Treatment Editorial Board. PDQ Myeloproliferative Neoplasms Treatment. Bethesda, MD: National Cancer Institute. Updated <09/27/24>. Available at: https://www.cancer.gov/types/myeloproliferative/hp/myeloproliferative-neoplasms-treatment. Accessed <01/22/25>. [PMID: 26389291]
Section: Myeloproliferative Neoplasms Treatment (PDQ®)–Health Professional Version
Pages: https://www.cancer.gov/types/myeloproliferative/hp/myeloproliferative-neoplasms-treatment#_5
Section: Myeloproliferative Neoplasms Treatment (PDQ®)–Health Professional Version
Pages: https://www.cancer.gov/types/myeloproliferative/hp/myeloproliferative-neoplasms-treatment#_5
