Disseminated histoplasmosis in acquired immunodeficiency syndrome: light and electron microscopic observations.

Two young homosexual men with acquired immunodeficiency syndrome (AIDS) presented with five-lobe pneumonia and maculopapular rash, respectively, and were found to have disseminated histoplasmosis by examination of peripheral blood smears. Bone marrow smears from one patient revealed more numerous Histoplasma capsulatum organisms than peripheral blood smears did. Electron microscopy of peripheral-blood buffy coat demonstrated histoplasma organisms in monocytes and neutrophils as well as tubuloreticular structures in small lymphocytes. A search for Histoplasma capsulatum in peripheral blood smears from patients with AIDS is warranted, especially in endemic midwestern states.