[Malignant hemangioendothelioma of the thyroid gland]

A case of malignant hemangioendothelioma, developing in a goiter of a 52-year-old woman is presented. This bleeding tumor of the thyroid gland has caused four operations within one month. Histologically, the tumor was composed of widely dilated, ramifying and intercommunicating vascular spaces lined by atypical malignant endothelial cells. Positive immunohistochemical reactions with endothelial markers including factor VIII-related protein, and CD34 and non reactivity with epithelial membrane antigen (EMA) and thyroglobulin, confirmed the endothelial origin of this tumor.