[Progressive lymphangiokeratoma and angiosarcoma (Stewart-Treves syndrome) in congenital lymphedema].

Three unusual clinical and histopathological changes were found in a 59-year-old male patient with congenital lymphedema of the lower left leg. Firstly, a keratotic lymphangioma had developed in the course of only a few years and in the end involved the entire left leg up to the buttocks--far beyond the edematous area. Secondly, concealed beneath the lymphangiokeratoma, a solitary tumor almost the size of a table-tennis ball was found on the outer side of the lower left leg. Histopathologically, the tumor proved to be a malignant angiosarcoma, which had grown over a period of some months. It was characterized histopathologically by solid and angiomatous differentiation. Thirdly, the superficial and deep lymph vessels revealed remarkable atypia and papillary proliferations of endothelial cells. After amputation of the left leg at the thigh, with complete removal of the angiosarcoma, but leaving the pathologically altered vessels in the upper part of the left leg and the buttocks, no clinical signs of metastases of progression have been noted during the first year after operation.