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Histoplasmosis is an endemic infection caused by Histoplasma capsulatum, leading to a wide spectrum of disease from asymptomatic to severe disseminated disease. Histoplasma capsulatum is a dimrophic fungus presenting with a yeast form in body temperature and a hyaline mold form in the natural environment. The HE stained bone marrow biopsy reveals yeast forms that are are round or ellipsoidal  app 2-5 μm in diameter surrounded by a clear halo. Most of these yeasts are intracellular in macrophage, histiocyte, neutrophil and some may be outside macrophages.