Pulmonary involvement in the acquired immunodeficiency syndrome.

M ore than 50 percent ofpatients with the acquired immunodeficiency syndrome (AIDS) have involvement of the lungs.’ The defects in cell-mediated immunity that characterize AIDS predispose to a variety of pulmonary infections caused by pathogens that by and large are considered to be opportunistic.2 Chiefamong these is Pneumocystis carinii followed by Mycobacterium avium-intracellulare, cytomegalovirus, and Cryptococcus neoformans. Nonopportunistic organisms such as M tuberculosis, Histoplasma capsulatum, Coccidioides immitis, and Legionella pneumophila may also be encountered, although the diagnosis of diseases caused by these agents, even in a patient from a recognized high risk group, does not establish the diagnosis of AIDS. The surveillance definition of AIDS accepted currently by the Centers for Disease Control (CDC) is as follows: the presence of a reliably diagnosed disease at least moderately indicative ofunderlying cellular immunodeficiency (Kaposi’s sarcoma in a patient less than 60 years ofage, P carinii pneumonia or other opportunistic infections) occurring in the absence of known causes of underlying immunodeficiency and any other reduced resistance reported to be associated with the disease (immunosuppressive therapy, lymphoreticular As indicated in the definition, Kaposi’s sarcoma is one of the disorders associated with and diagnostic of AIDS. This neoplasm may involve the lungs as well as other viscera, and thus, must be included in a review the pulmonary manifestations of AIDS. This discussion will review briefly the epidemiologic features and immunologic abnormalities of AIDS and will focus more specifically on the pulmonary diagnostic evaluation of patients with AIDS or suspected AIDS and the management of the lung infections that are encountered frequently. A more comprehensive