Stewart-Treves syndrome: an histogenetic (ultrastructural and immunohistological) study.

One case of the so-called "Stewart-Treves syndrome" (STS), appearing on a lymphoedematous arm complicating radical mastectomy for breast cancer, was characterized electronmicroscopically and immunohistologically, in order to elucidate its disputed (epithelial vs endothelial) histogenesis. Epithelial and endothelial differentiation markers used comprised: antibodies against keratin, vimentin, factor VIII-related antigen (F VIII-RA), HLA-DR antigens and the lectin Ulex europeaus agglutinin I (UEA I). At the ultrastructural level, neoplastic cells were found to contain typical Weibel-Palade bodies, whereas by immunohistological techniques they proved to be keratin-negative/vimentin+, F VIII-RA+, UEAI+, HLA-DR+. These results rule out a possible epithelial differentiation and strongly favour an endothelial one for STS.