Epithelial markers in thyroid carcinoma: an immunoperoxidase study.

Ten cases each of papillary, follicular, anaplastic and medullary carcinoma of the thyroid were stained for thyroglobulin, calcitonin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA) and cytokeratin (CAM 5.2). Monoclonal or affinity purified polyclonal antibodies, and an indirect immunoperoxidase technique were used. All the papillary and follicular tumours, 5/10 anaplastic and 3/10 medullary carcinomas contained thyroglobulin. Only the 10 medullary carcinomas stained positively for calcitonin. Three out of 10 papillary, 1/10 follicular, 0/10 anaplastic and 10/10 medullary carcinomas were positive for CEA. Nine out of ten papillary, 7/10 follicular, 2/10 anaplastic and 3/10 medullary carcinomas were positive for EMA. Ten out of 10 papillary, 10/10 follicular, 5/10 anaplastic and 10/10 medullary carcinomas were positive for cytokeratin. The presence of calcitonin and CEA is of value in the diagnosis of medullary carcinoma, and enable its distinction from anaplastic thyroid carcinoma. Thyroglobulin is a useful marker in thyroid carcinomas.