Intravascular ("intimal") epithelioid angiosarcoma: clinicopathological and immunohistochemical analysis of three cases.

Angiosarcomas are rare malignant mesenchymal tumours, characterized morphologically by anastomosing vascular channels lined by atypical and proliferative active endothelial cells. An epithelioid cytomorphology of tumour cells is often seen focally in angiosarcoma, whereas purely epithelioid angiosarcomas are rare. Although angiosarcomas show a vascular differentiation they are almost never confined to pre-existing blood vessels. We describe three cases of intravascular epithelioid angiosarcoma arising in the carotid artery of a 60-year-old man, in the infrarenal part of the abdominal aorta and both renal arteries of a 69-year-old woman, and in the abdominal aorta of a 68-year-old man. In all cases malignant tumour tissue was found incidentally after disobliteration of thrombosed vessels. Histologically, purely epithelioid angiosarcoma composed of solid sheets of epithelioid tumour cells was seen; immunohistochemistry confirmed the endothelial differentiation of neoplastic cells. The reported cases show that angiosarcoma can occasionally arise within a pre-existing vessel.