Light and electron microscopic studies of the bone marrow and blood cells in chronic panmyelosis including polycythemia vera and primary thrombocythemia.

Both bone marrow and peripheral blood was investigated light and electron microscopically in 3 cases with polycythemia vera, 2 cases with primary thrombocythemia and 1 case with panmyelosis. In 5 cases the peripheral blood showed persistent increase in cells of two or three hematopoietic systems. Giant thrombocytes in the peripheral blood were seen in 3 cases. Erythroblasts, granulocytic young forms, and megakaryocytes were often observed in the blood. Histologic bone marrow examination showed prominent proliferation of all 3 hematopoietic cells in every case. Cytological and electron microscopical examinations of the bone marrow revealed many mitotic figures, morphological abnormalities, and unbalanced nucleocytoplasmic maturation in various hematopoietic cells. These findings suggested that the proliferation of all 3 hematopoietic cells in the bone marrow was not simply reactive in nature, but an idiopathic progressive process. It is considered that these disorders and primary myelosclerosis represent no separate entities and must be unified as "chronic panmyelosis".