JMML


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  • Clinical

    • children
    • organomegaly: liver and spleen involvement in virtually all cases
    • lymphadenopathy in half
    • monocytosis, increased Hgb F
    • associations: NF1
    • Noonan syndrome can develop a self-resolving JMML condition

  • Criteria

    • monocytosis > 1E9/L
    • two of the following
      • increased Hgb F
      • immature granulocytes in blood
      • WBC > 10E9/L
      • clonal chromosomal abnormality
      • GM-CSF hypersensitivity of myeloid progenitors in vitro
    • rule out CML, AML
      • lack Ph chr or BCR-ABL1
      • blasts < 20%

  • Morphology

    • blood
      • leukocytosis: neutrophils, precursors and monocytes
      • anemia, nucleated RBCs
      • thrombocytopenia
    • marrow
      • hypercellular, granulocytic proliferation
      • minimal dysplasia, but can be present
    • infiltration into liver, spleen, skin, lungs

  • Molecular

    • monosomy 7 (25%)
    • mutually exclusive: PTPN11 (35%), RAS (10%), NF1 (10%)
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