Diagnosing Pneumocystis carinii pneumonia by cytological examination of bronchoalveolar lavage fluid: report of 15 cases.

Sixty episodes of pneumonia occurring in 53 immunosuppressed patients were investigated by bronchoalveolar lavage. Pneumocystis carinii was diagnosed on 15 (25%) occasions. In all cases the Papanicolaou stained lavage fluid presented a distinctive appearance and contained abundant, often biphasic, staining, "honeycomb" debris, and few alveolar macrophages. The Grocott methenamine silver technique confirmed the presence of characteristic cystic organisms in the debris in all 15 instances. Cysts containing internal sporozoites were identified in Gram stained material only with difficulty. Neither May-Grünwald-Giemsa stain nor fluorescence microscopy under ultraviolet light were effective for routine investigation.