Accessory thyroid gland at carotid bifurcation presenting as a carotid body tumor: case report and review of the literature.

Patients with carotid body tumors referred to vascular surgeons usually undergo magnetic resonance imaging (MRI) as part of the workup. We present a case report of a 39-year-old woman with a presumed carotid body tumor, as was expected from clinical and MRI findings. At surgery, the ectopic thyroid tissue was suspected, and resection was performed. Histologic examination showed normal thyroid tissue with no sign of malignancy. Postoperative thyroid analysis showed a normally located, properly functioning thyroid gland. Ectopic thyroid glands are generally found in the midline, as a result of abnormal median migration. Their presence lateral to the midline with a proper functioning thyroid gland in its normal position is extremely rare. Although several submandibular thyroid glands have been reported, a close relation with the carotid arteries was described only once. When MRI scans of a presumed carotid body tumor show tumor characteristics that are not fully specific for a carotid body tumor, the possibility of ectopic thyroid tissue should be entertained, which can be the patient's only properly functioning thyroid tissue. In such cases, additional assessment, including thyroid tests, should be considered before surgery.