Idiopathic acquired sideroblastic anemia terminating in acute myelosclerosis.

Acute myelosclerosis is an unusual myeloproliferative syndrome characterized by pancytopenia, absence of massive hepatosplenomegaly, and an absence of tear-drop poikilocytes. The marrow is usually fibrotic with atypical megakaryocytic and trilinear dyspoiesis. Median survival is approximately six months from onset of symptoms. The authors report a case of acute myelosclerosis that evolved in a patient two and one-half years after the onset of idiopathic acquired sideroblastic anemia. A review of the other previously reported case of this unusual transformation and comments on the pathogenesis of the transformation from idiopathic acquired sideroblastic anemia to acute myelofibrosis are included.