Hemophagocytosis. This is bone marrow (hematoxylin and eosin stain) from a 49-year-old male with hepatitis C, who presented with fever of unknown origin and multi-organ failure. Bone marrow biopsy revealed hypercellularity with diffuse histiocytic infiltrate and hemophagocytosis. Clusters of lymphocytes in the bone marrow were positive for Epstein-Barr virus (EBV) by in situ hybridization, and peripheral blood was positive for EBV by polymerase chain reaction (PCR). This image shows two hemophagocytic macrophages. Note the lipid-laden macrophage on the bottom right, which appears to contain a neutrophil.