#00062395

A 74 year old immunocompetent male with a remote history of temporal arteritis presented with fevers, night sweats, weight loss, and profound fatigue over 2-3 months.  Evaluation over a month by medicine, infectious disease and rheumatology revealed mildly progressing adenopathy and splenomegaly, with minimal anemia and thrombocytopenia, transaminitis, and a slightly elevated LDH. An extensive infectious was unrevealing, a diagnosis of lymphoma was suspected and hematology was consulted. A peripheral smear revealed toxic granulation, vacuoles, and dohle bodies (panel A), with a few tears and early white cells, without nucleated red cells. A bone marrow was performed for cultures (MAI/fungal), and to rule out a lymphoproliferative disorder. The aspirate demonstrated multiple areas of organisms consistent with histoplasma (panel B); this was also seen on the biopsy, clot section, PAS stain, and Gomori methenamine silver staining (panel C- F). Subsequently, histoplasma urine and serum testing were positive, confirming the microscopic findings. The patient later revealed his hobby of “caving” in various areas of the US over numerous years (the last three years ago), which is the likely origin of the histoplasmosis.

Disseminated histoplasmosis is classically seen in immunosuppressed patients. The incidence in immunocompetent patients is not well described. Cases describing Histoplasma capsulatum in the bone marrow in immunocompetent patients have been mentioned mostly in underdeveloped countries.