Erythroid hypoplasia in myelofibrosis: a feature associated with blastic transformation.

Four cases of myelofibrosis have shown a pattern which is usually found only where there is erythroid hypoplasia and in none of these was there evidence of extramedullary erythropoiesis. Three of these cases terminated in a blastic phase. The findings suggest that the occurrence of erythroid hypoplasia in myelofibrosis may be associated with blastic transformation--whether as a predisposing factor or as a secondary event is still speculative. This phenomenon is discussed in relation to the natural history of myelofibrosis.