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Case 153 - Discussion

Hematopathology Case


Transient Abnormal Myelopoiesis (TAM)

  • Previously called "transient myeloproliferative disorder (TMD)"

  • In 10% neonates with Down syndrome

  • Nearly always arises in the first week of life

  • Very high white cell count and splenomegaly

  • Positive: dim CD45, dim HLA-DR, CD34, CD38, CD41, CD61, CD71, CD117

  • Often aberrant expression of CD7 and CD56

  • CD13-, CD11b -

  • Trisomy 21 and frequent mutation of GATA1

  • Complete resolution without therapy, ~46 days

  • 30% will develop true AML later, mostly megakaryoblastic leukemia

  • DDX: Megakaryoblastic leukemia in Down syndrome

    • Arises at 1-5 years old.

    • CD13 and CD11b positive

    • Highly sensitive to chemotherapy