Thyroglossal Duct Cysts

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https://en.wikipedia.org/wiki/Thyroglossal_cyst

Thyroglossal duct cysts are the most common form of congenital neck cyst. Thyroglossal duct cysts may arise during the fifth week of embryonic life after the descent of the thyroid gland from the base of the tongue to its position in the neck. The failure of the tract to involute by the 7th week results in the presence of a sinus tract and cyst(s) in the midline of the neck. The cyst can occur anywhere along the thyroglossal duct tract from the foramen cecum at the base of the tongue to the level of the suprasternal notch. The cysts are most commonly located inferiorly to the hyoid bone within 2 cm of the midline with a close relationship to the hyoid, thyrohyoid membrane, or thyroid cartilage. They are rarely so far lateral to be confused with a branchial cleft cyst. In rare instances, they may be located at the base of the tongue and cause swallowing and respiratory difficulties in the neonate. 

The cyst is an epithelial remnant of the thyroglossal tract, and as such is composed of thick mucous material lined with secreting columnar or squamous epithelium.  A thick fibrous capsule surrounds the cyst. 

The incidence in males and females is 1:1. 

Diagnosis

  1. Usually presents as a painless firm nodule in the midline of the neck. It is not usually associated with dysphagia. It is not noticeable until after the first year of life and often noted by the parent or during a routine examination.  Most are diagnosed before age 5.
  2. Cysts that are lower in the neck tend to be more off the midline because of the presence of the thyroid cartilage.
  3. Thyroglossal duct cysts will usually move up with swallowing or protrusion of the tongue
  4. May get infected and present as a swollen, red, hot, and very tender mass. This may be the initial presentation.
  5. Ultrasound will demonstrate a midline cystic lesion. 

Differential Diagnosis

  1. Dermoid cyst
  2. Lymph node
  3. Cystic hygroma
  4. Branchial cyst
  5. Lipoma
  6. Laryngocele
  7. Thyroid nodule

Treatment

  1. Infected cyst treated with antibiotic to cover oropharyngeal flora (aerobes and anaerobes) and warm compresses. Fine needle aspiration (FNA) should be obtained for gram stain and culture when possible.  FNA is also helpful to confirm the diagnosis. I&D if antibiotics are unsuccessful.
  2. After inflammation is gone, surgical removal is recommended.
    1. Must be sure that you are not removing the child's only thyroid tissue, although an ectopic thyroid gland is usually not in the midline. At the time of surgery, if not clearly a cyst, biopsy should be performed before removal of the mass.
    2. Thyroid scan, ultrasound, or CT should be done prior to the surgery to confirm that there is presence of normal thyroid tissue. Palpation is not adequate.
    3. Most common procedure to remove is the Sistrunk procedure: resect the cyst and the mid-portion of the hyoid.
    4. Percutaneous ethanol injection can be tried for children who are not surgical candidates.  However, only effective in 1/3 of patients.
  3. Recurrences of the cyst in about 5% of cases. Recurrence is more likely if removal is done when inflammation/infection is present.
  4. Presence of carcinoma present within a cyst is <1%.

References

  1. Brousseau, V. J., et. al. (2003). Thyroglossal duct cysts: presentation and management in children versus adults. International Journal of Pediatric Otorhinolaryngology, 67, 1285-1230.
  2. Huoh, K.C., et. al. (2012). Comparison of imaging modalities in pediatric thyroglossal duct cysts. The Laryngoscope, 122, 1405-1408.
  3. Ostlie, D.J., et. al. (2004). Thyroglossal duct infections and surgical outcomes. J. Pediatr. Surg., 39, 396-399.
  4. Turkyilmaz, Z. et. al. (2004). Management of thyroglossal duct cysts in children. Pediatrics International, 46, 77-80.

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