Zur Histogenese der Angiomatosis Kaposi

A bullous variant of Kaposi's sarcoma in an elderly female

We report the case of Kaposi's Sarcoma (KS) in an elderly Italian female that has slowly progressed and evolved clinically with bullous formation. The skin biopsy was diagnostic of KS, showing the typical spindle cell formations, but at the same time showing a labyrinth-like collection of vessels that correlated with the bullous nature of the clinical lesions. Immunohistochemical staining for factor VIII antigens demonstrated strong reactivity of non-neoplastic blood vessel endothelium but virtually no staining of tumor cells. This is similar to the reactivity of normal lymphatic endothelial cells and supports the notion that these labyrinth-like vessels are derived from lymphatic endothelium.

[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.

CONCLUSION

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