ANGIOMATOID CARCINOMA AND ANGIOSARCOMA OF THE THYROID-GLAND - A SPECTRUM OF ENDOTHELIAL DIFFERENTIATION

The existence of angiosarcoma of the thyroid gland and its relation to angiomatoid carcinoma have been debated. The authors reviewed eight a ngiomatoid thyroid neoplasms. Controls consisted of six sarcomatoid th yroid carcinomas without angiomatoid features and an angiosarcoma meta static to the thyroid gland. All eight angiomatoid neoplasms consisted of epithelioid cells with prominent eosinophilic cytoplasm lining vas cularlike spaces. All eight expressed vimentin. Four tumors were predo minantly angiosarcomalike neoplasms, based on staining for factor VIII -related antigen (three of four), CD31 (four of four), CD34 (one of fo ur), and Ulex europaeus I lectin (four of four); they lacked epithelia l markers other than cytokeratin (two of four). Four tumors were desig nated as angiomatoid carcinomas, based on staining for multiple epithe lial markers: cytokeratin (four of four), epithelial membrane antigen (three of four), thyroglobulin (three of four). Three angiomatoid carc inomas also expressed or labeled with one or more vascular markers: CD 34 (one of four), CD31 (two of four), Ulex europaeus I lectin (one of four), factor VIII-related antigen (one of four). The metastatic angio sarcoma to the thyroid gland labeled for factor VIII-related antigen, vimentin, CD31, and with Ulex europeaus I lectin. It did not express C D34. The sis sarcomatoid carcinomas without angiomatoid features stain ed for cytokeratin (four of six), epithelial membrane antigen (one of six), and vimentin (six of six). None labeled for thyroglobulin, facto r VIII-related antigen, CD31, CD34, or with Ulex europaeus I lectin. A ngiomatoid carcinomas of the thyroid gland exhibit both epithelial and endothelial features. ''Angiosarcoma'' may represent the extreme in t his spectrum of endothelial differentiation. All tumors behaved in a s imilar clinical fashion characterized by persistent local disease, wid espread metastases and poor prognosis.