[Pneumocystis carinii pneumonia--a review].

Pneumocystis carinii pneumonia is a clinically, roentgenologically, and serologically uncharacteristic pneumonia of the immunodeficient patient and is caused by the opportunistic parasite Pneumocystis which is most likely a protozoon. The untreated disease is lethal. The epidemiologic, clinic, and histologic features of P. carinii pneumonia are different from those of the interstitial plasmacellular pneumonia that occurred in malnourished and premature infants between 1930 and 1960 in Europe and was caused by the same organism. P. carinii is restricted to the alveoli of the lung. Material for the direct microscopic diagnosis of the parasite can be produced by bronchoalveolar lavage. The trophozoites of P. carinii are preferably stained by Giemsa stain and the cystwalls by methenamine-silver. For a reliable diagnosis both methods should be used.