A central midline neck swelling is noted in a 4 yr old girl posted for tonsillectomy. The swelling is, painless, mobile, and cystic, just below the hyoid bone of size 2 x 1.1 x 1 cm. U/S showed a thick walled cystic lesion. Management would include:

Ans. is 'a' i.e. Surgical removal This girl is having thyroglossal cyst.Thyroglossal duct cysts are the most common congenital cysts in the neck.They are also the most common midline swelling in the neck Thyroglossal cystIt is cystic swelling developed in the remnant of the thyroglossal duct or tractSite - 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,SuprahyoidIn the floor of mouthBeneath the foramen caecumIt 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 it's a congenital swelling most common age of presentation is between 2 to 4 yrs.Mobility - Cyst can be moved sideways but not verticallyPeculiar characteristic which helps in distinguishing thyroglossal cyst from other neck swellingit moves up with protrusion of tongue as the thyroglossal tract is attached to the tongue.It also moves with deglutition so do all thyroid swellings, subhyoid bursitis, sublingual desmoid.Cyst is lined by pseudostratified columnar epithelium and squamous epithelium.Heterotopic thyroid tissue may be present in 20% of cases.ComplicationsRecurrent infection,Formation of thyroglossal fistulaCarcinomatous change (usually papillary carcinoma.)Treatment - Treatment involves the "Sistrunk operation" which consists of compete excision of the cyst in continuity with its tract, the central portion of the hyoid bone, and the tissue above the hyoid bone extending to the base of the tongue. Failure to remove these tissues results in a high recurrence rate.Note-Thyroglossal cyst is congenital but thyroglossal fistula is never congenital. It follows infection or inadequate removal of a thyroglossal cyst.