Hairy cell leukemia. Disease pattern and prognosis.

The authors reviewed the clinical course of 31 consecutive patients with hairy cell leukemia seen at the University of California Los Angeles. The clinical presentation included varying degrees of pancytopenia, splenomegaly, and bone marrow infiltration with hairy cells. Ten patients were identified as having an "atypical" disease, which is defined as absence of palpable splenomegaly and/or marrow cellularity of less than 45%. These atypical patients had clinically milder disease and significantly less anemia than the usual patient (mean hemoglobin, 12.1 g/dl versus 9.4 g/dl; P = 0.016), although neutropenia and thrombocytopenia were comparable. Mortality and infection rates were similar in both groups. Infections were common in all patients, but opportunistic infections and septicemia were rare in patients prior to initiation of therapy. Two thirds of the patients who received corticosteroids and/or cytotoxic agents had serious infections, with a 50% mortality rate. Nearly 70% of the neutropenic patients (leukocyte count less than 1000) who received any form of treatment had a serious infection. The most important factors predicting mortality were chemotherapy and an age older than 50 years. Patients who survived 2 years with their disease had an excellent prognosis, and four patients in this series are alive and well with their disease for more than 10 years.