Thyroid-associated antigens in routinely embedded carcinomas. Possibilities and limitations studied in 116 cases.

Routinely embedded tumors (116 cases) were screened immunohistochemically for the thyroid-associated antigens, thyroglobulin and calcitonin, and for carcinoembryonic antigen (CEA). Also the influence of different fixatives, decalcification, and embedding procedures were studied. All follicular and papillary carcinomas stained positive for thyroglobulin; 14 of the 23 undifferentiated carcinomas showed only a focal and weak reaction for thyroglobulin. The metastases showed the same reaction pattern as the primary lesion. Calcitonin was present only in the medullary carcinomas and in 2 of the 23 undifferentiated carcinomas. Carcinoembryonic antigen was not present frequently in the investigated carcinomas. The reliability of the method, its clinical importance, and the possibilities it offers for a more precise classification are discussed. The diagnostic value of the method is illustrated by two case reports.