Ectopic thyroid follicular carcinoma in the right mandible: a case report.

[BACKGROUND] Ectopic thyroid carcinoma in the mandible is extraordinarily rare; few histologically proven cases have been reported in the literature. Embryologically, cases of ectopic thyroid occur with a developmental abnormality during the migration of the thyroid gland from the floor of the primitive foregut to its final position in the neck. Ectopic thyroid tissue can be found around the course of the thyroglossal duct or laterally in the neck, and even in the mediastinum or below the diaphragm. Since 90% of ectopic thyroid tissues are located at tongue bases, the mandible ectopic thyroid gland is extremely rare. Theoretically, ectopic thyroid glands in the mandible are unlikely to become cancerous. Clinically, follicular carcinoma is less common than papillary carcinoma in both the ectopic thyroid regions and the eutopic anterior neck position. This case is the first to report a cancerous ectopic thyroid in the mandibular bone with eutopic thyroid follicular adenoma and adenomatous goiter.

[CASE DESCRIPTION] Here, we report a case of mandible follicular thyroid cancer (MFTC). A 72-year-old male was presented with a chief complaint of pain and discomfort in the lower right back tooth that had persisted for over 3 months, with cone-beam computed tomography (CBCT) revealing a mass in the right mandible. The patient's mandible mass was removed via right hemimandibulectomy, and reconstruction was simultaneously performed using free autogenous rib grafts. The postoperative pathology diagnosis revealed follicular thyroid carcinoma. In addition, this patient underwent a total thyroidectomy at another hospital 3 years ago for benign thyroid lesions.

[CONCLUSIONS] In conclusion, we present a rare case of ectopic follicular thyroid carcinoma located in the right mandible, accompanied by benign eutopic thyroid lesions. Effective management of such cases necessitates a multidisciplinary approach, and surgical resection is recommended for ectopic follicular thyroid carcinoma.