Thyroglossal duct cyst

What it is

A thyroglossal duct cyst is a congenital midline neck mass. It arises in the route of the thyroglossal duct, extending from the tongue (foramen caecum) to the thyroid gland in the neck, and it is a cystic expansion of a remnant of the thyroglossal duct tract. Among neck masses it sits with the central group, next to thyroid mass, submental lymphadenopathy and cervical cleft, and not with the anterior triangle group (branchial cyst, submandibular abscess, thyroid nodule, laryngocele) or the posterior triangle group (cystic hygroma, clavicular tumor, cold abscess). It is usually in children, and one text has it typically present in patients < 20 years old, but up to 40% present after 20 years old.

How it presents

The cyst is at the midline below the hyoid bone, and it moves upwards on tongue protrusion. On swallowing the two are not the same: one text has it move with swallowing as well, and one text has it move with tongue protrusion and not with swallowing. It enlarges with URTI. If infected, it is tender and there is erythema.