Ectopic thyroid tissue presenting as a carotid body paraganglioma

Ectopic thyroid tissue is a rare developmental abnormality, typically presenting with midline ectopia due to incomplete embryological migration via the thyroglossal duct. The presence of ectopic thyroid tissue lateral to the midline is very rare, accounting for 1–3% of all ectopic thyroid tissue. Clinically, these lesions are often mistaken for other diagnoses including enlarged lymph nodes or metastatic tumours. We present a case of lateral ectopic thyroid tissue presenting as a presumed carotid body paraganglioma in a middle-aged woman. The patient presented with a slow-growing lateral neck mass which was clinically and radiologically consistent with a carotid body paraganglioma. She subsequently underwent tumour excision after which histological analysis identified ectopic thyroid tissue with no evidence of malignancy.