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Childhood Acute Myeloid Leukemia/Other Myeloid Malignancies Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Juvenile Myelomonocytic Leukemia

Juvenile myelomonocytic leukemia (JMML), formerly termed juvenile chronic myeloid leukemia, is a rare hematopoietic malignancy of childhood accounting for less than 1% of all childhood leukemias.[1] A number of clinical and laboratory features distinguish JMML from adult-type chronic myeloid leukemia. The diagnostic criteria that need to be met for JMML are included in Table 5.[2,3]

Table 5. Diagnostic Criteria for Juvenile Myelomonocytic Leukemia (JMML)

Category 1 (all of the following)aCategory 2 (at least one of the following)b,cCategory 3 (two of the following if no category 2 criteria are met)a,d
GM-CSF = granulocyte-macrophage colony-stimulating factor.
a Current World Health Organization (WHO) criteria.
b Proposed additions to the WHO criteria that were discussed by participants attending the JMML Symposium in Atlanta, Georgia in 2008.[2]CBLmutations were discovered subsequent to the symposium and should be screened for in the workup of a patient with suspected JMML.[3]
c Patients 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.
d Patients who are not found to have a category 2 lesion must meet the category 1 and 3 criteria.
e Note 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.
Absence of theBCR/ABL1fusion geneSomatic mutation inRASorPTPN11White blood cell count >10 × 109 /L
>1 × 109 /L circulating monocytesClinical diagnosis of NF1 orNF1gene mutationCirculating myeloid precursors
<20% blasts in the bone marrowMonosomy 7Increased hemoglobin F for age
Splenomegalyb,e Clonal cytogenetic abnormality excluding monosomy 7b
  GM-CSF hypersensitivity

The pathogenesis of JMML has been closely linked to activation of the RAS oncogene pathway, along with related syndromes (see Figure 1).[2,3] In addition, distinctive RNA expression and DNA methylation patterns have been reported; they are correlated with clinical factors such as age and appear to be associated with prognosis.[4,5]


cdr0000712808.jpg
Figure 1. Schematic diagram showing ligand-stimulated Ras activation, the Ras-Erk pathway, and the gene mutations found to date contributing to the neuro-cardio-facio-cutaneous congenital disorders and JMML. NL/MGCL: Noonan-like/multiple giant cell lesion; CFC: cardia-facio-cutaneous; JMML: juvenile myelomonocytic leukemia. Reprinted from Leukemia Research, 33 (3), Rebecca J. Chan, Todd Cooper, Christian P. Kratz, Brian Weiss, Mignon L. Loh, Juvenile myelomonocytic leukemia: A report from the 2nd International JMML Symposium, Pages 355-62, Copyright 2009, with permission from Elsevier.

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