Acute Megakaryoblastic Leukemia: Importance of Bone Marrow Biopsy in Diagnosis.

Five cases of megakaryoblastic leukemia, presenting as "de novo" acute leukemias are reported. They represented 7.2% of all cases of adult acute non-lymphoblastic leukemias (ANLL) seen in our Hematology Service during the past 30 months. These cases showed features of predominantly blast proliferation with a marked increase of reticulin fibres in the bone marrow. One case had features of acute leukemia with trilineage myelodysplasia and one had a more chronic evolution with splenomegaly initially resembling a myeloproliferative syndrome. In all cases, the definitive diagnosis was made on bone marrow histology as cytology was poor and the blast cells were positive for factor VIII with the immunoperoxidase technique. The importance of bone marrow histology is emphasized.