Acute myelofibrosis: a report of three cases.

This report describes three cases of an atypical variant of agnogenic myeloid metaplasia characterized by pancytopenia, high peripheral blast cell count, lack of significant splenomegaly or tear-drop poikilocytosis, and diffuse marrow fibrosis with an abnormal proliferation of megakaryocytes. It is suggested that these cases represent an acute variant of agnogenic myeloid metaplasia that is distinct from either the terminal blastic transformation of myelofibrosis or acute granulocytic leukemia.