Cytopathology of opportunistic infection in bronchoalveolar lavage.

Bronchoalveolar lavage is an important tool for the cytologic and microbiologic examination of the lung. Silver- or Papanicolaou-stained slides from 604 lavage specimens from 344 patients were evaluated for the presence of fungal, parasitic, and viral organisms. Yeast, pseudohyphae, or hyphae occurred in 155 specimens (25.7%). Candida was the most frequent opportunistic fungus in immunosuppressed hosts. Patients with clinically significant Candida infection had many budding yeasts and pseudohyphae on cytologic preparations of their lavage fluid. Aspergillus, which occurred in five patients, was readily identified by cytologic examination and by fungal culture. Pneumocystis carinii was found in 14 patients (4%). Cytopathologic characteristics of Herpes simplex or cytomegalovirus were present in four patients (1.2%). In 414 specimens no pathogens were identified by either microbial culture or cytologic examination; usually, these patients had pulmonary hemorrhage, recurrent neoplasia, or therapy-induced lung disease to account for their abnormal chest x-rays. Cytologic and microbiologic examination of lavage fluid readily identified opportunistic pathogens. The ease and low morbidity of bronchoalveolar lavage support its use in the assessment of pulmonary infiltrates in immunocompromised hosts.