2-chlorodeoxyadenosine (cladribine) in the treatment of hairy cell leukemia.

Hairy cell leukemia is an uncommon chronic B cell lymphoproliferative disorder in Taiwan and only sporadic cases have been noted. This disease is often found in middle-aged men with the typical manifestations of pancytopenia and splenomegaly. While tartrate-resistant acid phosphatase (TRAP) stain of the neoplastic cells in peripheral blood smear is positive in 90% cases, bone marrow examination is still necessary for diagnosis. For treatment, splenectomy and interferon have been the standard strategies. Recently, newly-developed purine analogues, 2-chlorodeoxyadenosine (cladribine) and 2'-deoxycorfomycin (pentostatin), were found to achieve long lasting complete remission. Here we reported a 48-year-old men who was found to have splenomegaly and bicytopenia incidentally at routine physical checkup. Although the TRAP staining of peripheral blood showed negative result, hairy cell leukemia was finally diagnosed by bone marrow biopsy. The following splenectomy showed a typical picture of hairy cell leukemia on pathology, but cytopenia recovered only partially after surgery. One course of chemotherapy with cladribine (0.1 mg/kg/day continuous intravenous infusion for 7 days) was given after recovery from major surgery. The white cell and platelet counts normalized after treatment and he carried a stable condition thereafter. Since the disease is rare and purine analogues are newly developed, there has been no report on using 2-clorodeoxy-adenosine against hairy cell leukemia in our country. Here we suggest that newly developed purine analogues such as cladribine are the first choice of treatment in cases of hairy cell leukemia.