Acute megakaryoblastic leukaemia in children.

We report four children with acute megakaryoblastic leukaemia (AMKL) and compare their clinical course with 16 previously reported cases of AMKL in children. In adults, AMKL has been reported as a rapidly progressive disease characterized by pancytopenia associated with bone marrow fibrosis, absence of organomegaly, and unresponsiveness to therapy. Although some of the childhood cases present with these features, the clinical course can be quite variable, particularly in young children, with both organomegaly and leucocytosis occurring. Down syndrome, or other constitutional abnormalities of chromosome 21 were present in four of 20 reported cases. Two of the four cases reported herein were initially diagnosed cytologically as childhood acute lymphoblastic leukaemia (ALL). All four patients achieved a complete remission, and three remain in remission from 34 to 56 months from diagnosis. Greater recognition of AMKL in the future will help to clarify the disease characteristics, prognosis and optimal treatment of this unusual form of leukaemia.