[Stewart-Treves syndrome. Apropos of a case with ultrastructural study].

An optical and ultrastructural study was performed on biopsy and autopsy specimens of Stewart Treves syndrome cutaneous tumours and their metatases. Various histological aspects are described: territories presenting typical vascular differentiation, spindle cell "Kaposi type" territories and undifferentiated territories. The ultrastructural study confirmed the angiomatous differentiation of these tumors and revealed a certain number of arguments in favor of blood rather than lymphatic capillary differentiation of the newly formed vessels. Upon completion of this study, it appeared possible to confirm that the Stewart Treves syndrome corresponds to an anatomo-clinical entity whose histological features are very close to those of primitive cutaneous angiosarcomas.