Acute monoblastic leukemia: diagnosis and treatment of ten cases.

During a large clinicopathologic study of acute nonlymphocytic leukemia (ANLL), ten patients were identified in whom the leukemic blasts demonstrated striking morphologic and cytochemical similarities and who seemed to form a specific subgroup of ANLL. The patients' leukemic blasts were studied in routine blood and bone marrow preparations and by cytochemical and ultrastructural techniques. In routine smears, the blasts showed no clear evidence of differentiation. Cytochemically, the blasts exhibited strongly positive nonspecific esterase activity, which was completely inhibited by incubation with sodium fluoride, and were myeloperoxidase and sudan black B negative. Ultrastructural features of the blasts were similar to those described for monocytic leukemias. Striking clinical features included the occurrence primarily in young patients, the high frequency of lymphadenopathy at presentation, and the high incidence of post-treatment disseminated intravascular coagulation. Complete remissions were frequently initially obtained with duanorubicin in combination with various other agents and later in the disease with VP16-213. Based on the cytochemical and ultrastructural features, we concluded that this form of ANLL was a variety of acute monocytic leukemia. Recognition of the entity is important for optimal therapy.