RESUMEN
Two patients with systemic angioendotheliomatosis had prominent constitutional symptoms such as fever, loss of weight, and general weakness, and had multiple organ dysfunctions, including bizarre neurologic findings and dementia. Severe anemia that required frequent blood transfusions also was present. One patient developed severe hemolysis and hypersplenism that required splenectomy for relief; the other patient had intravascular hemolysis and autoimmune hemolytic anemia, which were treated unsuccessfully with conservative measures. In both cases, postmortem examination showed many large, noncohesive malignant cells within the lumen of the blood vessels in many of the organs. There was no infiltration or replacement of the normal tissues by the tumor cells. Histochemical studies showed that the tumor cells were pyroninophilic but did not have cytoplasmic immunoglobulins or activity of chloroacetate esterase and muramidase. The cells showed factor VIII antigen in their cytoplasm. Systemic angioendotheliomatosis may represent a true neoplastic process of the vascular endothelial cells.