The relationship of erythromonocytic leukemia to other myeloproliferative disorders

The evolution of erythromonocytic leukemia has been studied in two patients. One (Case 1) presented with DiGuglielmo's syndrome manifested by erythroid hyperplasia, dyserythropoiesis, periodic acid-Schiff-positive erythroblasts, normal heme biosynthesis and ineffective erythropoiesis. In vitro stimulation of the patient's bone marrow with exogenous erythropoietin demonstrated decreased responsiveness. Progressive infiltration of the bone marrow and peripheral blood with primitive monocytic cells was accompanied by an increased number of hypodiploid cells. The second patient (Case 2) presented with a picture of polycythemia vera, progressing to myelofibrosis and terminating as erythromonocytic leukemia in which a paroxysmal nocturnal hemoglobinuria-like defect was demonstrated in the erythroid cells. The leukemic cells were hyperdiploid. It is concluded that erythromonocytic leukemia may result from clonal evolution occurring in any of the myeloproliferative syndromes.