Megakaryoblastic transformation in myeloproliferative disorders.

Megakaryoblastic transformation, with cells showing characteristic morphology and ultrastructural cytochemistry, developed in two patients with agnogenic myeloid metaplasia or myelofibrosis, and in one with chronic granulocytic leukemia. From the onset of the leukemic phase, all three have followed a relatively benign clinical course, surviving for 48, 29, and 24 months, respectively; only hydroxyurea has been necessary to control thrombocytosis. This experience emphasizes that it is possible for a patient to have an improved quality of life with minimum chemotherapy. In contrast, megakaryoblastic leukemia or acute myelofibrosis, where splenomegaly and a leukoerythroblastic blood picture are typically absent, responds poorly to any form of chemotherapy, and survival is short.