Distinct effect of cyclophosphamide and cyclosporine on pure red cell aplasia associated with T-cell large granular lymphocyte leukemia.

Large granular lymphocyte (LGL) leukemia is characterized by a clonal proliferation of large-sized lymphocytes with prominent large azurophilic cytoplasmic granules. Although most cases of T-LGL leukemia are indolent and asymptomatic during the course of the disease, some present with pure red cell aplasia (PRCA) and require therapy. We here reported a case of T-LGL leukemia complicated by PRCA in which anemia was resistant to cyclosporine and had been controlled for several years by cyclophosphamide; however, progressive anemia developed despite the administration of cyclophosphamide, but was ameliorated by the re-administration of cyclosporine. The present case demonstrated the 3 different phases of T-LGL proliferation associated with anemia (1st, T-LGL leukemia; 2nd, polyclonal T-LGL expansion; 3rd, myelodysplastic syndrome). We also showed that cyclophosphamide was effective when PRCA was caused by increased numbers of LGL, whereas cyclosporine was administered when hypoplastic myelodysplastic syndrome was suspected as the main cause of anemia. Repetitive bone marrow examinations should be performed throughout the course of T-LGL in order to monitor combined myelodysplastic syndrome.