Peroxidase-negative and myelomonocytic antigen-positive acute leukemia

Between 1983-1988 bone marrow samples obtained from 195 peroxidase-negative leukemia patients were analyzed for their surface antigens. Thirteen of these patients (6.7%) had myelomonocytic-positive and lymphoid-negative antigens. These leukemic cells reacted with CD13 in eight patients, CD33 in seven, CD11 in six and CDw41 in two. In none of these patients did the leukemic cells react with CD1, CD2, CD3, CD4, CD5, CD8, CD10, CD19 or CD20. Leukemic cells from two patients were reactive with CD7. These leukemic cells demonstrated L2 morphology in 11 patients and L1 morphology in one patient. The leukemic cells from the final patient were diagnosed as those of leukemic transformation of myelodysplastic syndrome. Chromosomal abnormality was observed in approximately half of the patients examined (6/10). Cytochemical analysis revealed that the leukemic cells were negative for periodic acid Schiff stain but positive for acid phosphatase. The prognosis of these patients was markedly poor as compared to acute lymphocytic leukemia or typical peroxidase-positive nonlymphocytic leukemia. Complete remission was induced in only 30% of patients and duration of survival was short (4.7 months). This suggests that myelomonocytic antigen-positive peroxidase-negative acute leukemia is a distinct type of leukemia and may require more aggressive therapy to improve survival.