Rituximab in the treatment of the variant of hairy cell leukaemia: a case report.

Hairy cell leukaemia (HCL) is an uncommon, low-grade B-cell lymphoproliferative disorder. HCL-variant describes an entity of HCL that is important from the point of view of requiring differential diagnosis from HCL, and for requiring careful consideration of the treatment approach. HCL-variant differs from the classic form with respect to the lack of monocytopaenia, its elevated WBC and unique morphology and immunophenotype. Indeed, there is currently no adequate standard treatment for this condition - HCL-variant is generally resistant to interferon-alpha, and complete remission is rarely achieved with either pentostatin or cladribine. We report a 57-year-old female patient who presented at our institution in November 2004 with high white blood counts and splenomegaly. Based on her blood morphology, bone marrow and spleen histology, immunophenotype and clinical characteristics, the patient was diagnosed as having HCL-variant, with blastoid variant transformation. The patient had advanced-stage disease. She was initially treated with spleenctomy, which resulted in short-term normalization of blood counts. One month later the blood counts deteriorated, she developed peripheral and abdominal lymphadenopathy and had poor performance status. One cycle of cladribine combined with rituximab was immediately administered. We started with rituximab 375 mg/m(2), which resulted in a remarkable recovery of blood counts, followed by cladribine 0.1 mg/kg for 7 days. However, the patient's general condition worsened, and she subsequently died from heart failure. Our experience from this case suggests that rituximab is a promising therapy for patients with HCL-variant, particularly when combined with cladribine. However, further clinical study is required before rituximab can be considered as a front-line therapy for this form of malignancy.