Intrathyroidal Thyroglossal Duct CYST: A Rare Cause of Thyroiditis in an Adult

ABSTRACT Objective: Thyroglossal duct cysts (TDCs) are remnants of the thyroglossal duct that typically present as an asymptomatic mass along the midline of the neck in children or adolescents. Most are located in association with the hyoid bone, superior to the thyroid gland. An intrathyroidal TDC presenting as a thyroid abscess has not been previously described. Methods: We describe a rare case of intrathyroidal TDC that presented as acute pyogenic thyroiditis. Results: A 36-year-old male patient with no history of prior thyroid disease or neck infections presented with acute thyroiditis. Physical exam revealed a tender anterior neck mass, and biochemical evaluation was consistent with hyperthyroidism. Thyroid imaging and fine-needle aspiration showed a cystic thyroid nodule with pyogenic infection and chronic inflammation. The thyroid abscess recurred following initial medical treatment, and the patient underwent thyroid lobectomy. Histopathology revealed an intrathyroidal TDC. Conclusion: The possibility of TDC should be considered in patients with an infected cyst or thyroid nodule along the midline of the neck. Definitive treatment with surgical excision can prevent recurrent episodes of infection. Abbreviations: FNA fine-needle aspiration; TDC thyroglossal duct cyst