<prompt> Most common site of thyroglossal cyst is -SubhyoidSuprahyoidFloor of mouthBeneath foramen caecum  <response>: Ans. is a i.e., Subhyoid Thyroglossal cyst It is cystic swelling developed in the remnant of the thyroglossal duct or tract Site - It may be present in any part of the thyroglossal tract thyroglossal tract extends from foramen caecum to the isthmus of thyroid Common sites are: Subhyoid most common In the region of the thyroid cartilages, Suprahyoid In the floor of mouth Beneath the foramen caecum It is a midline swelling, except in the region of the thyroid cartilage, where the thyroglossal tract is pushed to one side, usually to the left. Though its a congenital swelling most common age of presentation is between 2 to 4 yrs. Mobility - Cyst can be moved sideways but not vertically Peculiar characterstic which helps in distinguishing thyroglossal cyst from other neck swelling It moves up with protrusion of tongue as the thyroglossal tract is attached to the tongue. It also moves with degluttionso do all thyroid swellings, subhyoid bursitis, sublingual desmoid. Cyst is lined by pseudostratified columnar epithelium and squamous epithelium with hetrotopic thyroid tissue present in 20 of cases.. Complications Recurrent infection, formation of thyroglossal fistula carcinomatous change usually Papillary carcinoma. Treatment: Treatment involves the uSistrunk operation which consists ofenbloc cystectomy and excision of the central hyoid bone to minimize recurrence. 