Expression of thyroid transcription factor 1 (TTF-1) in extra thyroidal sites: papillary thyroid carcinoma of branchial cleft cysts and thyroglossal duct cysts and struma ovarii

The thyroid-associated transcription factor-1 (TTF-1) is a nuclear tissue specific protein, found only in thyroid and thyroid tumors regardless of histologic type as well as in lung carcinomas. Most ectopic thyroid tissue are found along the thyroglossal duct tract and around the bilateral main lobes of thyroid glands. Ectopic thyroid tissue within a branchial cleft cyst is a rare abnormality and papillary carcinoma arising in this tissue is extremely rare. Thyroid tissue may also be found as one of the many components of teratoma, particularly those located in the ovary. The aim of this study is to evaluate, through immunohistochemistry, the expression of TTF-1 in branchial cleft cysts with ectopic normal thyroid tissue, in primary thyroid papillary carcinomas of branchial cleft cysts and thyroglossal duct cysts and in struma ovarii, in order to evaluate the expression of this antigen in extra thyroidal sites