Acute megakaryoblastic leukemia in Down's syndrome: report of a case and review of cytogenetic findings.

A case of a child with trisomy 21 and acute megakaryoblastic leukemia (AMBL) is reported. Histological examination of the bone marrow showed progressive fibrosis and replacement with megakaryoblasts. The diagnosis was confirmed by platelet peroxidase reaction and immunofluorescent staining with anti-factor VIII. Serial cytogenetic studies using banding techniques at various stages during the course of the disease (preleukemia, leukemia, remission, and relapse) showed several chromosomal abnormalities (unbalanced translocation between chromosomes 1 and 4 leading to trisomy 1q, trisomy 7q, monosomy 7p, and a reciprocal translocation between chromosomes 10 and 16). AMBL in childhood is probably more common than previously reported. Any association between AMBL and a particular cytogenetic abnormality must await further cytogenetic studies, specifically those employing banding techniques.