[Megakaryocyte proportion versus nucleated cells in the peripheral blood showing leukoerythroblastosis]

Megakaryocytes in the peripheral blood in which leukoerythroblastosis was recognized were studied by electron microscopy on the vertically cut section of the buffy coat of the blood, and percentages of them in 10,000 nucleated cells distributed from the top of the bottom of the buffy coat were counted. In 15 of 31 patients, percentages of peripheral blood megakaryocytes ranging from 0.01% to 0.64% were seen. There was difference of the result among diseases shown peripheral blood megakaryocytes. Namely, in patients with myelofibrosis and CML, in whom extramedullary hematopoiesis was predominant, many cases ascertained peripheral blood megakaryocytes were demonstrated. Because of this result, the extramedullary hematopoiesis appears to play an important role to the presentation of megakaryocytes in the peripheral blood. On the other hand, patients indicating both megakaryocytes and abnormal sideroblasts in the peripheral blood had sideroblastic anemia marrow. This result seems to show that a part of megakaryocytes are directly flowed out from the marrow into the blood simultaneously accompanied with abnormal sideroblasts.