The patient with a known diagnosis of CLL presented with a fever and sudden onset of fatigue. His hemoglobin on this admission was 7.5g/dl. Other laboratory studies included an elevated LDH, an elevated ferritin level, and a decreased haptoglobin. Coombs' test was negative. His bone marrow aspirate a background lymphocytosis in addition to scattered myeloid elements at all stages of maturation. Of particular interest is the macrophage in the lower center of the image phagocytizing four intermediate erythroid precursors, consistent with hemophagocytic lymphohistiocytosis (HLH).