A 44-year-old HIV-positive man with CD4 count of 47 × 10-6/L (410-1545 × 10-6/L) was admitted for acute renal failure, profound hypoglycemia, and hemodynamic instability in the setting of pentamidine treatment for Pneumocystis jirovecii pneumonia. A bone marrow biopsy , performed to investigate progressive pancytopenia (hemoglobin 65 g/L, neutrophils 0.41 × 109/L, and platelets 23 × 109/L) revealed innumerable oval/crescent-shaped yeast cells in both intracellular and extracellular distribution, most seen within marrow histiocytes (panel A). Periodic acid-Schiff positively stained the organisms (panel B). A working differential diagnosis of histoplasmosis (Histoplasma capsulatum) or Penicillium marneffei infection with histoplasma capsulatum confirmed by culture and PCR. Histoplasma capsulatum and Penicillium marneffei are opportunistic fungi occasionally disseminated in AIDS patients.