A Rare Case of Carcinoma in the Thyroglossal Duct Cyst of an Elderly Patient.

Thyroglossal duct cysts are the most common congenital abnormalities of the neck, constituting about 70% of all cervical neck masses in children and 7% of the adult population. The occurrence of carcinoma in a thyroglossal duct cyst is very rare (less than 1%). Malignancy of the thyroglossal duct cyst usually presents in the third or fourth decade of life. We report a case of carcinoma in the thyroglossal duct cyst, which presented for the first time in our elderly patient.  A 76-year-old male presented with a 6 x 5 cm swelling in the anterior aspect of the neck. The swelling had been present for three months and had a variegated consistency. It moved with deglutition as well as with protrusion of the tongue. Intra-operatively, the lesion was cystic and was adherent to the hyoid bone. Sistrunk operation was done. The post-operative histopathology showed papillary carcinoma in the thyroglossal duct cyst.  The standard treatment is Sistrunk procedure with close follow-up of the patient. Patients with metastatic disease require a total thyroidectomy and in the presence of neck secondaries, neck dissection has to be done. The diagnosis can be missed because of the rarity of this condition. Carcinoma should be suspected in a thyroglossal duct cyst when presenting for the first time in the elderly age group.