Diagnosis of histoplasmosis in bronchoalveolar lavage fluid by intracytoplasmic localization of silver-positive yeast.

A case of histoplasmosis in a patient with acquired immunodeficiency syndrome is presented. Intracytoplasmic organisms were found in Diff-Quik- and Papanicolaou-stained bronchoalveolar lavage fluid sediment. Budding yeasts were found in the silver methenamine-stained material. It was initially thought that the yeasts might represent another infecting organism, especially in view of the patient's history of esophageal candidiasis. When the silver-stained material was counterstained with hematoxylin and eosin, simultaneous demonstration of cytologic detail and silver positivity showed that the silver-positive yeasts were intracellular, confirming that they were Histoplasma capsulatum. Counterstaining with hematoxylin and eosin allows localization of argyrophilic organisms to either intracellular or extracellular sites and is technically simple to perform. It is useful in acquired immunodeficiency syndrome patients and other immunocompromised hosts, in whom multiple organisms are often found.