Clear-Cell Follicular Adenoma of Ectopic Thyroid in the Submandibular Region.

A case of clear-cell follicular adenoma arising in ectopic thyroid tissue is reported. The 2.0-cm tumor arose in the submandibular region in a 29-yr-old female. The diagnosis was established on the basis of light microscopic morphology, a positive thyroglobulin immunohistology, and the presence of normal thyroid tissue surrounding the mass. Preoperative computed tomography (CT) scan and postoperative ultrasound studies revealed a normal orthotopic thyroid gland. No additional tumors have since been detected. The patient is free of recurrent or metastatic disease 54 mo following excision of the mass. Only eight previously published reports have described ectopic thyroid tissue in the submandibular region, all but one of which lacked an orthotopic thyroid gland. In this article, we describe the pathological features of our case and review the existing literature on the subject.