Chronic myeloid leukemia associated with pure red cell aplasia and terminating in promyelocytic transformation.

After intermittent treatment with busulphan over a 7-year period for chronic myeloid leukemia (CML) in chronic phase, a 39-year-old female developed leukocytosis in association with pure red cell aplasia (PRCA). Bone marrow examination confirmed erythroid aplasia, and culture revealed a total absence of erythroid progenitor cells. The patient then was treated with azathioprine, corticosteroids, cyclophosphamide, plasma exchange, and cyclosporin A, but she remained erythroblastopenic and transfusion dependent for more than a year, at which time a promyelocytic transformation supervened. The authors propose that this sequence of events, hitherto unreported, is a manifestation of the multistep progression of CML.