Rare presentation of thyroglossal duct cyst after radiation therapy to the neck.

Thyroglossal duct cyst (TDC) is a congenital lesion which usually manifests as an enlarging painless neck mass in a child or young adult. We highlight an unusual presentation of TDC in an adult which developed after radiation therapy to the neck. We discuss the probable sequence of events and emphasize the need for radiologists, radiation oncologists and the surgeons to be aware of this entity when evaluating patients after radiation therapy.