Introduction:
Birth defects are structural abnormalities or persistent anatomical structures present at birth that affect one in 33 babies in the United States alone. The abnormality can affect any organ in the body, and the symptoms mainly depend on the extent of the abnormality. For example, the thyroglossal duct is a structure that fails to disintegrate after birth. Normally, the thyroid gland descends from its initial position (near the back portion of the tongue) to its final place (in the neck) during its development. The duct usually disintegrates by the 10th week of pregnancy. If any part of the duct remains without disintegration, it becomes prone to inflammation and cyst formation.
What Is a Thyroglossal Tract Cyst?
It is essential to understand the term before understanding the pathology behind the thyroglossal duct cyst.
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Thyroid: Related to or representing the thyroid gland.
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Glossal: Tongue.
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Duct or Tract: Any tube or vessel carrying secretions.
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Cyst: A cavity or a sac-like structure containing fluid, air, or other substances.
A thyroglossal tract cyst is a non-cancerous mass developing in the neck due to infection or inflammation of the remnant thyroglossal duct. The cyst is usually filled with fluid or mucus.
What Are the Features of a Thyroglossal Tract Cyst?
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The cysts are usually small and measure up to two centimeters in diameter.
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It is diagnosed in children below ten years of age or sometimes adults.
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According to reports, seven percent of children in the United States develop thyroglossal duct cyst.
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70 % of all congenital defects in the neck are diagnosed as thyroglossal duct cysts.
What Causes a Thyroglossal Tract Cyst?
The thyroglossal tract cyst is a congenital disability. During the development of the thyroid gland, it moves down from the base of the tongue to the neck through the thyroglossal duct. Therefore, the duct has to disappear by the end of pregnancy. If portions of the duct remain, they form cavities or pockets in the form of cysts. These cysts may become enlarged or infected, causing symptoms.
What Are the Symptoms of a Thyroglossal Tract Cyst?
The symptoms of a thyroglossal tract cyst vary from child to child. They resemble other growths or masses in the neck. However, the following are the most common symptoms experienced:
1. Presence of a small, movable, round mass in the center of the neck.
2. Pain and tenderness if the cyst is infected.
3. Redness over the skin of the cyst.
4. Drainage of contents of the skin through a small opening from the cyst.
5. Large cysts cause difficulty in breathing or swallowing.
How Is a Thyroglossal Tract Cyst Diagnosed?
The thyroglossal duct cyst should be suspected if the child develops swelling in the neck. The diagnosis involves a physical examination and specialized tests. An ear, nose, and throat specialist (ENT) specialist is usually recommended for further evaluation. Tests that aid in diagnosis include:
1. Physical Examination: Characteristically, the mass moves with swallowing or protrusion of the tongue, which reflects the attachment to the hyoid bone. If the patient has a midline mass in the neck that does not move with swallowing, a pathologic entity other than a thyroglossal cyst should be considered.
2. Blood Tests - To check the function of the thyroid gland.
3. Ultrasound Scan - Uses sound waves to produce images of the cyst and thyroid gland.
4. CT (Computed Tomography) Scans - CT scans with or without contrast dye to produce images for visualization and location of the cyst. X-rays are passed through the neck, and digital images are produced.
5. Fine Needle Aspiration Cytology (FNAC) - A small needle is inserted into the cyst, and the contents are drawn into the syringe for further examination.
6. Thyroid Scans - It is a procedure that utilizes radioactive forms of iodine or technetium to detect structural abnormalities in the thyroid gland.
What Is the Treatment for Thyroglossal Tract Cyst?
Surgery is the treatment of choice for a thyroglossal tract cyst. But the treatment also depends on the patient's overall health, location and size of the cyst, and the symptoms. The recurrence rate is around 45 % to 55 % with a simple excisional surgery. Therefore, surgeons follow a technique called the Sistrunk procedure. It involves the removal of the cyst along with its connection to the base of the tongue and a portion of the hyoid bone (a small horseshoe-shaped bone located at the bottom of the tongue and in front of the neck).
Note:
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Before carrying out the surgery, antibiotic treatment should be started if the cyst is infected.
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The surgery is carried out for 90 minutes under general anesthesia.
What Are the Risks Associated With a Thyroglossal Tract Cyst?
Complications of Cyst Surgery:
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Bleeding.
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Clotting of the blood.
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Formation of a fistula.
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Postoperative infections.
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Scarring of the surgical site.
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Rarely damage to the nerve controlling the tongue can occur.
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Hypothyroidism if the cyst contains functional thyroid tissue.
Complications of Persistent Cyst:
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Cancer - Thyroglossal tract cysts are usually harmless. In rare cases (less than one percent), a cancerous transformation of the cyst has been reported. Adults are more likely to develop cancer than children. It is always recommended to get the cyst removed before any complications occur.
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Some cysts enlarge and expand due to infection. This can cause difficulty in breathing and swallowing food.
Conclusion:
The thyroglossal duct tract is a non-cancerous mass developing in the neck due to infection or inflammation of the remnant thyroglossal duct. The cyst is usually filled with fluid or mucus and measures up to two centimeters in diameter. It is diagnosed within ten years of the child’s life. The symptoms of the thyroglossal duct cyst include the presence of a small, movable, round mass, pain, tenderness, redness, and drainage of contents of the skin through a small opening from the cyst. Large cysts cause difficulty in breathing or swallowing. The diagnosis is made after a physical examination and specialized tests like ultrasound and CT scans. Sistrunk surgery is the treatment of choice. Overall, the thyroglossal tract cyst can be easily managed and has a good prognosis.
