[The histogenesis of Kaposi sarcoma: a histochemical and electronmicroscopical study (author's transl)]

1. Histologically, Morbus Kaposi is primarily characterized by a proliferation of streams composed of spindle-shaped cells, by vascular slits lined by cells, and by a minor cellular inflammatory reaction. 2. The cells lining the vascular slits resemble endothelial cells and exhibit strong alkaline phosphatase activity and a clear leucinaminopeptidase activity. They contain Weibel-Palade bodies. 3. The ultrastructural analysis of the tumor cells shows a proliferative formation resembling capillary sprouts with and without lumina. The lumina are composed primarily of poorly differentiated endothelial cells. A second typical cellular component are fibroblast-like tumor cells possibly derived from perithelial cells. 4. Indicative of M.K. are also extravasation and phagocytosis of erythrocytes with intracytoplasmic decomposition, and storage of myelinlike structures somewhat resembling Schwannian-cells. 5.

M.K. is characterized by a multifocal neoplasia of capillary like structures and by a progressive sarcomatous development.