Dual organism infection in biopsy specimens from immunocompromised patients: two cases demonstrated by immunocytochemistry.

We report two cases in which immunocytochemistry demonstrated simultaneous infections within a single biopsy specimen obtained from each of two immunocompromised patients in whom multiple organism infection was not suspected. Using a rapid immunocytochemical technique, Pneumocystis carinii and Cryptococcus neoformans were demonstrated in a transbronchial lung biopsy from the first patient; Candida and cytomegalovirus were demonstrated in an endoscopic biopsy of the esophagus from the second patient. Routine hematoxylin and eosin as well as special stains failed to establish the presence of more than one infectious agent in either case. Mycology cultures ultimately confirmed the presence of Cryptococcus in the first case, but cultures were not performed in the second case due to the scant amount of tissue obtained from the biopsy. The results indicate that concurrent infection by more than one opportunistic organism in immunocompromised patients can easily remain unrecognized. The use of immunocytochemistry may thus provide an important adjunct to routine and special stains or specific cultures.