SQUAMOUS-CELL CARCINOMA ARISING FROM THYROGLOSSAL DUCT REMNANTS - REPORT OF A CASE AND RESULTS OF IMMUNOHISTOCHEMICAL STUDIES

We report on the case of a 57-year-old male found to have squamous cel l carcinoma (SCC) arising from thyroglossal duct remnants. The patient presented with an asymptomatic tumor in his anterior neck which was i mmovable on palpation, Aspiration biopsy cytology revealed class V mal ignancy with many atypical clusters and marked keratinization, After p reoperative radiation, a radical operation employing Sistrunk's proced ure with bilateral neck dissection was performed, Histopathological ex amination confirmed a diagnosis of moderately differentiated SCC, but revealed ciliated columnar epithelium in the walls of the cyst without a normal layer of squamous cells, Furthermore, immunohistochemical st udies demonstrated the tumor to be negative for thyroglobulin staining , but positive for cytokeratin and carcinoembryonic antigen, These his topathological findings proved attributable to squamous metaplasia occ urring in the ciliated columnar epithelium of the thyroglossal duct, T hus, SCC might originate in the metaplastic portion of the thyroglossa l duct remnants, Although the prognosis associated with SCC in the thy roglossal duct is not as optimistic as that associated with papillary carcinoma, no evidence of recurrence has been observed in this patient in the 7 years since his operation. This suggests the effectiveness o f our therapeutic approach for this unusual disease.