Table 7

Diagnostic criteria for juvenile myelomonocytic leukemia (JMML) [5, 87].

Clinical and hematological criteria (all 4 criteria are required)

- Peripheral blood monocyte count ≥1×10⁹/L

- Blast percentage in peripheral blood and bone marrow of <20%

- Splenomegaly

- No Philadelphia (Ph) chromosome or BCR-ABL1 fusion

Genetic criteria (any 1 criterion is sufficient)

- Somatic mutation^a) in PTPN11, KRAS, or NRAS

- Clinical diagnosis of neurofibromatosis type 1 or NF1 mutation

- Germline CBL mutation and loss of heterozygosity of CBL^b)

Other criteria

Cases that do not meet any of the genetic criteria above must meet the following criteria in addition to the clinical and hematological criteria above:

- Monosomy 7 or any other chromosomal abnormality or

- ≥2 of the following:

- Increased hemoglobin F for age

- Myeloid or erythroid precursors on peripheral blood smear

- Granulocyte-macrophage colony-stimulating factor (also called CSF2) hypersensitivity in colony assay

- Hyperphosphorylation of STAT5

^a)If a mutation is found in PTPN11, KRAS, or NRAS, it is essential to consider that it might be a germline mutation and the diagnosis of transient abnormal myelopoiesis of Noonan syndrome must be considered. ^b)Occasional cases have heterozygous splice-site mutations.

Blood Res 2021;56:S51~S64 https://doi.org/10.5045/br.2021.2021010