Ringed sideroblasts in primary myelodysplasia. Leukemic propensity and prognostic factors.

Among 123 patients with ringed sideroblasts on bone marrow aspirates, 85 had acquired ringed sideroblasts with primary myelodysplasia. The patients were placed in categories modified from the French-American-British classification based on percentages of ringed sideroblasts and myeloblasts in the initial bone marrow. Overall, 48% (41/85) of patients with myelodysplasia developed acute leukemia. Primary acquired sideroblastic anemia was the most favorable category with longer survival and 13.8% (4/29) leukemic conversions. Variables correlating with leukemic transformation included male sex, thrombocytopenia, neutropenia, and pseudo-Pelger-Huët neutrophils. Only two variables had independent predictive value by multivariate regression analysis: a high percentage of myeloblasts and a low percentage of ringed sideroblasts. Numerous ringed sideroblasts strongly predicts a more favorable course in myelodysplastic patients.