Malignant myelosclerosis.

Malignant myelosclerosis, as described by Lewis and Szur, is characterized by an acute, rapidly fatal illness, with anemia, leukopenia, thrombocytopenia, myeloblasts in the blood, and a "dry tap" on bone marrow aspiration. This entity has been only rarely reported in the American literature. We report three additional cases of myelosclerosis. The patients were 70, 37, and 46 years old with a survival of eight weeks, six weeks, and 11 months, respectively. Bone marrow biopsy specimen showed fibrosis in tow with increased reticulum fibers and blast cells in all. At autopsy, the spleen and liver wereinfiltrated with leukemic cells. In two cases, the lymph nodes were involved. Extramedullary erythropoiesis was also seen. We believe that malignant myelosclerosis is best interpreted as an acute myeloproliferative disorder sharing features with acute leukemia and agnogenic myeloid metaplasia.