Thyroglossal Duct Cyst
A thyroglossal duct cyst is a cystic remnant of the tract that thyroid cells take during early fetal development from the base of the tongue to its postnatal location in the middle to lower neck. Normally, the remnants of this tract obliterate late in the first trimester, but if cells of this tract persist, they can give rise to a midline cystic remnant known as a thyroglossal duct cyst. Thyroglossal duct cysts can occur anywhere along the thyroglossal duct, but are most commonly found at or below the level of the hyoid bone in the upper neck. Cells of the thyroglossal duct cyst secrete mucus which can gradually cause the cyst to grow.
Presentation
Thyroglossal duct cysts are the most common form of congenital cysts of the neck. Two-thirds are diagnosed before age 30, half present in early childhood. They are often identified by a round, firm, midline upper neck mass. The cyst moves with swallowing or sticking out the tongue. Children with a thyroglossal duct cyst are usually asymptomatic, but may complain of some tenderness to palpation. Approximately a third present with infection which manifests as redness, tenderness, an increase in size, and occasionally spontaneous drainage. Very rarely, the cyst may cause difficulty swallowing or breathing.
Diagnosis
A thyroglossal duct cyst is usually diagnosed during a history and physical. It occasionally follows an upper respiratory illness. Diagnostic tests may include blood work to assess thyroid function and an ultrasound to assess the characteristics of the lesion and to document the presence of a normal thyroid gland.