FIGURE 120.9 Thyroglossal duct cyst (Reprinted with permission from Snell RS Clinical Anatomy 7th ed Baltimore, MD: Lippincott Williams & Wilkins; 2005:CD418.) Thyroglossal duct cysts are among the more common midline neck masses in children and are the most common congenital mass of the neck in this age group Approximately 40% present before 10 years of age They are composed of an ectodermal ductal remnant that fails to regress after fetal descent of the thyroid gland They may occur anywhere along the path of descent of the thyroid, from the base of the tongue to the sternal notch, although they most commonly occur near the level of the hyoid bone Presentation is usually that of a painless, smooth, mobile, cystic mass that is located in the midline or just slightly off-center ( Fig 120.9 ) Because of its intimate association with the hyoid, the mass moves with protrusion of the tongue or swallowing On occasion, an overlying pore is present Cysts may go unnoticed until infection occurs, causing acute swelling, pain, and erythema of the overlying skin Patients with asymptomatic thyroglossal duct cysts should be referred for elective surgical excision If the thyroglossal duct cyst is infected on presentation, excision is deferred until appropriate antimicrobial therapy is completed and inflammation has subsided If incision and drainage are required during treatment, the patient should be referred to a surgeon