What is a thyroglossal duct cyst?
A thyroglossal duct cyst is a mass or lump in the front part of neck that is filled with fluid. While a baby is developing in the womb, the thyroid gland begins at the base of the tongue. Before birth the thyroid gland moves in the neck to its usual position below the thyroid cartilage and above the sternum. A portion of this path in which the thyroid gland moves may fill with mucus-like fluid, creating a thyroglossal duct cyst.
Thyroglossal Duct Cyst | Diagnosis & Treatments
How is a thyroglossal duct cyst diagnosed?
A thyroglossal duct cyst is often initially discovered during a physical examination in child who is showing no other symptoms. Either the family or the physician detects the mass in the upper midline neck.
Since a variety of different masses can occur in the neck, an imaging study needs to be performed. Generally this study is a cervical ultrasound, although sometimes a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan may be requested.
The purpose of the imaging is to determine whether the mass is cystic rather than solid and to document the presence of a normal thyroid gland in the lower neck. A solid neck mass with no distal thyroid gland raises concern of a so-called “ectopic thyroid” in which the neck mass represents all the child’s thyroid tissue. This is fortunately a rare occurrence.
There are other congenital cystic neck masses that can closely resemble a thyroglossal duct cyst. The most common is a dermoid cyst. Sometimes even a dermoid cyst cannot be distinguished from a thyroglossal duct cyst, based on the combination of the physical examination and imaging studies, and the answer is not known until the mass is removed and examined by a pathologist.
How is a thyroglossal duct cyst treated?
The treatment for a thyroglossal duct cyst is surgical removal. There is no known medical therapy with the exception of infected thyroglossal duct cysts, which require immediate antibiotic treatment. The infection should be resolved before surgery is performed. It is well documented that the removal of a thyroglossal duct cyst before it becomes infected results in a better outcome than if the cyst is removed after previous infection.
Surgical treatment requires not only the removal of the cyst, but also its potential connection to the base of the tongue in order to prevent recurrence. This includes removal of the central portion of the hyoid bone, since this connection can be anterior (in front of), posterior (in back of), or actually within the bone itself. This operation is called a Sistrunk procedure. The recurrence rate can be up to 50 percent if the central portion of the hyoid bone is not removed.
Complications of a Sistrunk procedure include those common to any open neck operation such as hematoma, seroma, or postoperative infection. The removal of the central portion of the hyoid bone has no adverse effect on the child’s swallowing or speaking.
Recurrence of a thyroglossal duct cyst may occur even when a proper Sistrunk procedure has been performed. This risk is higher if the cyst has been previously infected.