Red cell fragmentation in human disease (a light and scanning electron microscope study).

Although the mechanism of schizocyte formation has been amply documented in animal experiments and in in-vitro models, the fragmentation encounter between flowing red cells and fibrin strands has not previously been successfully demonstrated in human, microangiopathic disease. If blood flow is restored briefly in vitro immediately prior to tissue fixation, the instant of red cell fragmentation can be captured. Examination of tissue specimens fixed in this manner shows a pathophysiologic process that amplifies the findings previously described in other studies. In the patient under study, the microangiopathic process was widespread in all specimens of pulmonary and renal tissue that had been fixed after brief restoration of blood flow. Small arteries as well as the true microcirculation of both organs were involved. The microangiopathic process in the small arteries and arterioles presented as a partially occlusive thrombus of characteristic histology. The pulmonary capillaries contained linear fibrin microclots festooned with distorted and partially fragmented red cells. The microcirculation of the kidney showed the same findings as well as amorphous, sludged, occlusive red cell masses, particularly in the renal medulla.