Megakaryocytes in pulmonary blood vessels. 2. Relations to malignant haematological diseases especially leukaemia.

In a study of 71 autopsies in patients with malignant haematological disorders (55 leukaemias and 16 multiple myelomas) we found an increased number of megakaryocytes in the lung capillaries in only one of 55 cases of leukaemia (43 acute and 12 chronic leukaemias) with a mean value of 3 megakaryocytes per cm2. The incidence of pulmonary megakaryocytes in 16 cases of multiple myeloma was identical to that in an unselected, consecutive series of hospital autopsies. The discrepancy between the increased megakaryocytopoiesis and previously reported high number of circulating megakaryocytes in chronic myeloid leukaemia, and the few megakaryocytes in the pulmonary blood vessels of histological sections of autopsy specimens is discussed.