[Successful treatment with cladribine for hypoplastic hairy cell leukemia after long-term neutropenia]

A 34-year-old woman was admitted to the hospital because of swelling of her right knee, and the result of the laboratory tests indicated anemia and leukocytopenia. A bone marrow examination showed dissemination of small to medium-sized abnormal lymphocytes with abundant and pale blue cytoplasm and a circumferential "hairy" projection in the hypocellular bone marrow. These cells were positive for tartrate-resistant acid phosphatase (TRAP) and for CD 19, CD 20, CD 25, CD 103 and SmIg kappa. The patient was diagnosed as having hypoplastic hairy cell leukemia and received cladribine (2-CdA) for seven days via continuous intravenous injection. The minimum white blood cell count was 300/microl at seven days after starting the therapy (day 7) and the neutrophil count recovered to more than 1500/microl on day 118. The patient achieved complete remission on day 140 without any episodes of severe infection and has remained in complete remission for more than one year. The treatment of hypocellular HCL with 2-CdA might be useful.