Pneumonia in hairy-cell leukemia.

Hairy-cell leukemia (HCL) is an unusual malignant hematologic disorder involving splenomegaly, pancytopenia, and circulating mononuclear cells with prominent cytoplasmic projections. As in most forms of leukemia, the risk of pulmonary infection by normal pathogens and opportunistic invaders alike is high. HCL may be associated with granulomatous infections of the lung, especially mycobacterioses. Of the authors' series of 33 patients, 9 had a fungal or mycobacterial infection, including 5 atypical mycobacterial species. Five of the 6 patients with mycobacterioses and 1 of the 3 with fungal pneumonia survived the infection with appropriate therapy. Granulomatous infections, particularly mycobacterioses, should be seriously considered in the differential diagnosis of pulmonary parenchymal disease in a patient with HCl.