Clinical findings:
(1) The patient is a neonate who appears healthy. Rarely it may develop later in the first year of life.
(2) Hepatosplenomegaly may be present.
(3) If a rash is present, a skin biopsy does not show leukemic infiltration.
Hematologic parameters:
(1) Circulating blasts are seen in the peripheral blood. These are often heterogenous and may include megakaryoblasts, erythroblasts and/or myeloblasts. Auer rods are not seen.
(2) Usually anemia and thrombocytopenia are absent, but may be present.
Bone marrow features:
(1) The number of blasts in the marrow is typically less than in the peripheral blood and usually is < 60%.
(2) The abnormal proliferation may involved megakaryocytes, myeloid and/or erythroid cells.
(3) Blasts are immunophenotypically heterogenous.
Cytogenetics:
(1) This affects children with Trisomy 21. Rarely an affected child may be a mosaic with trisomy 21 involving the hematopoietic cells. Therefore, cytogenetics should be performed on blood or bone marrow if trisomy is not identified from other sources.
(2) Other cytogenetic abnormalities are typically absent but rarely may be found.
Followup:
(1) The condition spontaneously resolves, usually in 2 or 3 months.
(2) Children with transient myeloproliferative disorder are at risk for later developing acute leukemia, often megakaryoblastic. The children should be followed for evidence of leukemic transformation.
