EXTRAPULMONARY PNEUMOCYSTOSIS

Extrapulmonary pneumocystosis is an exceedingly rare complication of P neumocystis carinii pneumonia (PCP). Prior to the advent of the human immunodeficiency virus type 1 (HIV-1) epidemic, only 16 cases of extra pulmonary pneumocystosis in individuals who were immunocompromised by a variety of underlying diseases had been reported. Since the beginnin g of the HIV-1 and related PCP epidemic, at least 90 cases of extrapul monary pneumocystosis have been reported. This review briefly presents a history of the discovery of P. carinii and its recognition as a hum an pathogen, the controversy regarding its taxonomy, and the epidemiol ogy of this organism. A more detailed analysis of the incidence of ext rapulmonary pneumocystosis in HIV-1-infected individuals and its occur rence despite widespread prophylaxis for PCP with either aerosolized p entamidine or systemic dapsone-trimethoprim is presented. The clinical features of published cases of extrapulmonary pneumocystosis in non-H IV-1-infected individuals are summarized and contrasted with those in HIV-1 infected individuals. The diagnosis of extrapulmonary pneumocyst osis is discussed, and because clinical microbiologists and pathologis ts are the key individuals in establishing the diagnosis, the characte ristic microscopic morphology of P. carinii as its appears when staine d with a variety of stains is presented and reviewed. The review concl udes with a brief discussion of treatments for extrapulmonary pneumocy stosis.