Morphological and cytogenetic studies of angiosarcoma in Stewart-Treves syndrome.

A morphological and cytogenetic analysis of a multifocal angiosarcoma in a typical case of Stewart-Treves syndrome is reported. The morphological analysis indicated differentiation along both blood and lymph vessel endothelium lines. By light and electron microscopy there were areas with well-developed erythrocyte-containing, capillary-like vessels and poorly differentiated areas with abortive vascular formations. In these the endothelium revealed immunoreactivity to factor VIII RAg, binding of Ulex europaeus I and Psophocarpus tetragonolobus agglutinin lectins, Weibel-Palade bodies ultrastructurally and presented a continuous enclosing external lamina and immunoreactivity for laminin and collagen IV, all features of blood-vessel differentiation. There were also lymphangioma-like areas as well as poorly differentiated areas where the immunohistochemical, lectin-binding and ultrastructural features were compatible with a lymph vessel differentiation. Cytogenetic analysis of cultured tumour cells revealed chromosome counts in the diploid region. About 40% of the cells analysed had a normal diploid karyotype. The remaining cells showed a multitude of mainly nonclonal structural alterations; 17 unique marker types resulting from different translocations and deletions were observed. There were also a few cells with clonal numerical deviations showing monosomy 22, monosomy X and trisomy 2 respectively. It is of interest that the losses of chromosome 22 and the X chromosome also have been observed in Kaposi's sarcoma and that the PD-ECGF gene, a novel angiogenetic factor, has been mapped to chromosome 22.