Tuesday, September 25, 2007

Thyroglossal Duct Cyst

Thyroglossal duct cysts(TGDC) are the second most common neck masses. Approximately 7% of the adult population has thyroglossal remnants, with an equal sex distribution. (photo credit)

Thyroglossal duct cysts are cysts that are left over when the thyroid migrates from the base of the tongue into the neck before birth, leaving behind an epithelial trace known as the thyroglossal tract. This tract usually disappears during the 5th-10th gestational week. Incomplete atrophy of this tract, or retained epithelial cysts, creates the basis for the origin of TGDC. A thyroglossal remnant can be a cyst, a tract (or duct), a fistula, or an ectopic thyroid within a cyst or duct. The cyst usually lies in the middle of the neck in front of the "Adam's Apple".

Thyroglossal duct cysts usually show up in the first ten years of life, but may be found in older children or even adults. Most of the time it is a benign cyst that usually contains mucous or even pus-like fluid. (The incidence of primary carcinoma within the thyroglossal duct (TGD)varies in the literature, and ranges from 0.7%–1.6%. These figures pertain to patients of all ages, but in the pediatric population this cancer is even scarcer.)

Thyroglossal duct cysts are usually in the middle of the neck and seem to move up and down during swallowing. Because thyroid tissue may be inside the cyst, it is important to make sure that the thyroid gland has developed normally (and that not all the thyroid tissue is within the cyst). This is done by assessing the thyroid function by using blood tests (TSH, T3, T4), ultrasound exam, thyroid scans, or an MRI (scan credit)

Once these tests have been completed, excision of the cyst may be performed as an outpatient procedure. The common surgical procedure used to excise TGDC is the Sistrunk procedure, consisting of excision of the TGDC, the central portion of the body of the hyoid bone, and a core of tissue around the thyroglossal tract to open into the oral cavity at the foramen cecum. This allows the excision of all possible TGD remnants without actually visualizing them. The recurrence rate of thyroglossal remnants is 6%–10%.

If the only thyroid tissue found in the patient is located in the thyroglossal duct cyst, the treatment options are as follows:

  1. Remove the thyroglossal duct cyst and thyroid tissue, and start lifelong thyroid hormone replacement therapy (under a specialist's supervision)
  2. Attempt to keep the ectopic thyroid tissue in place, while stopping further growth of the tissue with medications (thyroxine - a thyroid hormone). Unfortunately, if the ectopic thyroid gland continues to cause symptoms in the patient (breathing or swallowing problems, bleeding or repeated infections), it will ultimately be recommended for removal.
  3. For those patients unable to tolerate surgery and who have failed a thyroid hormone trial, radiation therapy may be an option.

References

  • Thyroglossal Duct Cyst--Children's Hospital Web-Article
  • Thyroglossal Duct Cyst--University of Virginia Health System Web-Article
  • Thyroglossal Dust Cyst Excision--Pediatric Otolaryngology Web-site
  • Evaluation of neck masses in children. American Family Physician, 51:1904–191, 1995; Park YW
  • Thyroglossal Duct Cyst; American Family Physician, Sept, 1990 by Mark Girard, Salvatore A. Deluca
  • Hypothyroidism Following Removal of a "Thyroglossal Duct Cyst"; Plastic & Reconstructive Surgery. 68(6):930-932, December 1981; Conklin, William T. M.D.; Davis, Robert M. M.D.; Dabb, Richard W. M.D.; Reilly, Charles M. M.D.
  • The surgical treatment of cysts of the thyroglossal tract; Ann Surg 71:121–129, 1920; Sistrunk WF
  • Thyroglossal Duct Carcinoma in Children: Case Presentation and Review of the Literature --MedScape Article by Asaf Peretz; Esther Leiberman; Joseph Kapelushnik; Eli Hershkovitz

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