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Table 4. Diagnostic Criteria for Juvenile Myelomonocytic Leukemia (JMML)

Category 1 (all of the following)a Category 2 (at least one of the following)b,c Category 3 (two of the following if no category 2 criteria are met)a,d 
Absence of the BCR-ABL1 fusion geneSomatic mutation in RAS or PTPN11White blood cell count >10 × 109/L
>1 × 109/L circulating monocytesClinical diagnosis of NF1 or NF1 gene mutationCirculating myeloid precursors
<20% blasts in the bone marrowMonosomy 7Increased hemoglobin F for age
Splenomegalyb,eClonal cytogenetic abnormality excluding monosomy 7b
GM-CSF hypersensitivity

GM-CSF = granulocyte-macrophage colony-stimulating factor; NF1 = neurofibromatosis type 1.
aCurrent World Health Organization (WHO) criteria.
bProposed additions to the WHO criteria that were discussed by participants attending the JMML Symposium in Atlanta, Georgia in 2008.[190] CBL mutations were discovered subsequent to the symposium and should be screened for in the workup of a patient with suspected JMML.[191]
cPatients who are found to have a category 2 lesion need to meet the criteria in category 1 but do not need to meet the category 3 criteria.
dPatients who are not found to have a category 2 lesion must meet the category 1 and 3 criteria.
eNote that only 7% of patients with JMML will NOT present with splenomegaly but virtually all patients develop splenomegaly within several weeks to months of initial presentation.


  1. Chan RJ, Cooper T, Kratz CP, et al.: Juvenile myelomonocytic leukemia: a report from the 2nd International JMML Symposium. Leuk Res 33 (3): 355-62, 2009.  [PUBMED Abstract]

  2. Loh ML: Recent advances in the pathogenesis and treatment of juvenile myelomonocytic leukaemia. Br J Haematol 152 (6): 677-87, 2011.  [PUBMED Abstract]