CD5+immunophenotype in the bone marrow but not in the peripheral blood in a patient with hairy cell leukemia

We report the case of a patient with rare CD5+ hairy cell leukemia, which w as unusual, as there was also a discrepancy between the bone marrow and per ipheral blood immunophenotypes. We propose that some degree of maturation w ithin the malignant clone and the predominance of more mature CD5- hairy ce lls in the peripheral blood can explain this observation. The patient was t reated with a conventional course of cladribine (2'-chlorodeoxyadenosine) a nd achieved complete remission. We conclude that the unusual CD5+ immunophe notype of this patient did not affect prognosis or change the response to s tandard therapy. Copyright (C) 2000 S. Karger AG. Basel.