Some of the problems which we see on the infectious disease consultation service can be quite frustrating. This is one such case. A middle-aged man presented to our medical service with fever and dyspnea. His fulminant downhill course was characterized by anemia, jaundice, hypercalcemia, pulmonary abnormalities, and a lack of responsiveness to conventional antimicrobial therapy. At autopsy, malignant-appearing histiocytes were present in several organs including spleen, lymph nodes, and lung. Histopathological examination of tissues obtained at autopsy confirmed the presence of phagocytized erythrocytes within such histiocytes. This case aptly illustrates the hazy dividing line which sometimes exists between infectious and/or malignant processes which are, at present, still of undetermined etiology.