[Successful rituximab treatment in a patient with refractory hairy cell leukemia-Japanese variant and suffering from acute respiratory distress].

A 69-year-old man was referred to our hospital because of thrombocytopenia and was diagnosed as having hairy cell leukemia-Japanese variant (HCL-Jv) in December 2000. In June 2002, he was treated with pentostatin for progression of thrombocytopenia, but his response was incomplete. In addition, the number of hairy cells (HCs) in his peripheral blood (PB) began gradually to increase. He received treatment with interferon-alpha and cladribine, but he failed to respond completely to these treatments. The HCs in his PB decreased after splenic irradiation in July, 2004. However, he was admitted with acute respiratory distress in November. His white blood cell count was 123.1 X 10(9)/L with 91% HCs. Radiography and computed tomography of his chest revealed ground-glass opacity in both lungs. A bone marrow (BM) aspirate indicated increased cellularity with an 84% HC infiltration level. Based on these findings, we diagnosed pulmonary infiltration by HCs. Rituximab was administered weekly at a dose of 375 mg/m2, and he also received low-dose melphalan in a supportive role. After 8 courses of rituximab therapy, the HCs disappeared in his PB and BM, and his pulmonary infiltrates subsided. These results suggest that rituximab may be a very effective treatment for refractory HCL-Jv.