RESUMEN
A 38-year-old woman who presented with unexplained fever and pancytopenia was subjected to a bone marrow examination. Her bone marrow aspirate smear showed no obvious pathological finding except for the presence of hemophagocytosis and mild plasmacytosis. In view of hemophagocytosis, a thorough examination of the smear was conducted and revealed the presence of histoplasmosis. She was advised to undergo evaluation of her immunological status, and she tested positive for human immunodeficiency virus (HIV) infection. This case highlights that hemophagocytosis in the marrow may be an early sign of underlying disease, and that careful examination of bone marrow smears may reveal subtle infections. In addition, histoplasmosis with hemophagocytosis may be associated with pancytopenia, and hence, the HIV status of the patient should always be investigated.