IN NORMAL ANIMALS AND MAN, reticuloendothelial cells are a constant constituent of red bone marrow. The ratio of phagocytic cells to hematopoietic cells is relatively constant, so that the skeletal distributions of myeloid, erythyroid, and reticuloendothelial elements in normal animals are the same.1 Since knowledge of the distribution of the active marrow may be needed in investigative work on...

Haemophagocytic syndrome (HPS) should be included in the differential diagnosis of pyrexia of unknown origin (PUO). The hallmark of HPS is the accumulation of activated macrophages that engulf haematopoietic cells in the reticuloendothelial system. We describe a patient with unexplained fever in which a final diagnosis of HPS was established in a bone marrow study.

The appearance of a splenic hemangioma on radiocolloid scintigraphy has been reported to be that of a focal photon deficient (esion. We report a case of a patient who presented with the opposite appearance—that of a splenic "hot spot." We postulate that this appearance results from increased local blood flow presenting a greater proportion of colloid to the reticuloendothelial cells surrounding...