Epithelioid angiosarcoma of the thyroid gland. Report of two cases.

We present two cases of epithelioid angiosarcoma of the thyroid gland from two patients in Slovenia. In both cases, the tumor appeared as a dominant nodule in a multinodular goiter. Histological appearance of the tumor was similar in both cases and characterized by large epithelioid tumor cells with numerous intracytoplasmic lumina, large nuclei, and very prominent nucleoli. Such cells formed vascular structures as well. Neoplastic cells were positive for factor VIII-associated antigen in both cases. Reaction to Ulex europaeus lectin was positive in one case, and characteristic ultrastructural features were seen in another case. In both cases, some neoplastic cells also showed keratin positivity. Angiosarcoma is a rare but definite possibility in a differential diagnosis of anaplastic thyroid tumors in Slovenia.