Hemoglobin crystals phagocytized by polymorphonuclear leukocytes were seen in cytologic preparations of a cerebrospinal fluid and two pleural fluids. In the last two cases, the crystals were seen within erythrocytes and also free in the background. Intraerythrocytic crystallization of
hemoglobin is the result of polymerization of the
hemoglobin molecules; it occurs in peripheral blood in certain
hemoglobinopathies, being more pronounced in
hemoglobin C disease. In our three cases, in which the crystallization occurred not in peripheral blood but in fluids of confined body spaces, there was no clinical evidence of
hemoglobinopathy and blood
hemoglobin electrophoresis performed in one of the cases revealed normal
hemoglobin. Under laboratory conditions, we produced intraerythrocytic crystallization of
hemoglobin in hemorrhagic pleural fluid specimens by subjecting them to agents that induced decreased
oxygen concentration and osmotic
dehydration of the cells. We suggest that similar processes operative in fluid accumulated in confined body spaces produce crystallization of the
hemoglobin of extravasated red blood cells in the absence of
hemoglobinopathy.