Hairy Cell Leukemia, An Issue of Hematology/Oncology Clinics

Hairy cell leukemia (HCL) has assumed a level of great medical importance, despite its relative rarity as a chronic lymphoid leukemia. This is because it is a unique, and peculiar, clinicopathologic entity which demonstrates unparalleled sensitivity to systemic therapy. Accordingly, it has served as a model for rational drug development. Although splenectomy regularly normalizes the disease-associated cytopenias, it is now principally of historic interest because there are three agents approved to treat HCL, namely, interferon, pentostatin and cladribine. We found that single infusions of cladribine, administered continuously over seven days, induce response rates greater than 95%, 85% of which are complete and durable. More recently, the monoclonal antibody, rituximab, and the recombinant immunotoxin, BL22, have found application in the treatment of this disease. Given the effectiveness of systemic treatments in HCL, it is absolutely mandatory that this entity be recognized when present. In this issue of Hematology/Oncology Clinics of North America expert hematopathologists and clinicians, carefully selected, review the very latest pathologic, clinical and therapeutic advances in this disease, and deliberate how this information can be translated into a curative strategy.