Hairy-cell leukaemia: first-line treatment with cladribine or pentostatin.

(1) Hairy-cell leukaemia is a chronic lymphoid malignancy occurring in adulthood. It is rare and progresses slowly. The median survival time without treatment is about 4 years. The main presenting signs are infections and cytopenias (anaemia, thrombocytopenia, leukopenia). (2) Treatment is usually based on the purine analogues cladribine and pentostatin. About 80% of patients treated with cladribine or pentostatin survive for at least 10 years. (3) The main adverse effect of these treatments is the risk of infection, especially by Pneumocystis and herpes viruses, due to immunosuppression. Secondary cancers are frequent, but it is difficult to tell the extent to which these are caused by the disease or its treatment. (4) Interferon alfa and splenectomy are generally used when purine analogues fail.