Pulmonary disease caused by nontuberculous mycobacteria.

Nontuberculous mycobacterial pulmonary infections have become more common in recent years. The diagnosis is often overlooked because the findings may be subtle or because the radiographic appearance may change slowly or not at all for long periods of time. As a rule, the radiographic findings of nontuberculous mycobacterial pulmonary infections are identical to those of tuberculosis in any given patient. Cavitary disease in nontuberculous mycobacterial infections is less common than in tuberculosis. The most common radiographic finding is one or more areas of clustered fibroproductive nodules that change slowly. Mycobacterium kansasii infection responds well to therapy, whereas M avium-intracellulare infection is difficult to treat. Awareness of the radiographic appearance of the nontuberculous mycobacterial pulmonary infections will facilitate their diagnosis so that appropriate therapy may be initiated before the disease is far advanced.