Sistrunk Procedure (Thyroglossal Duct Cyst)
What the Examiner Expects
Excision of a thyroglossal duct cyst along with the central portion of the hyoid bone and the cyst tract extending to the base of the tongue (foramen cecum). The examiner expects you to recognize the classic presentation (midline neck mass that moves with swallowing and tongue protrusion, may become infected), differentiate from other midline neck masses (dermoid cyst, submental lymph node), and know that the Sistrunk procedure (removing the central hyoid bone) is essential to prevent recurrence (50% recurrence rate with simple excision alone). Preoperative thyroid ultrasound must confirm that a normal thyroid gland is present elsewhere — in rare cases, the thyroglossal duct remnant is the only thyroid tissue.
Key Examiner Focus Points
- Excision of the thyroglossal duct cyst, the central portion of the hyoid bone, and the tract to the foramen cecum
- Thyroglossal duct cyst is the most common midline neck mass in children
- Moves with swallowing AND tongue protrusion (unlike thyroid nodule which only moves with swallowing)
- Must confirm normal thyroid tissue exists before excision (the cyst may be the only thyroid tissue)
- Simple excision without hyoid bone resection has a 50% recurrence rate
Common Curveballs
Ultrasound shows no other thyroid tissue in the neck — the cyst appears to be the only thyroid
If the thyroglossal duct remnant is the patient's only thyroid tissue (ectopic thyroid), excision will render the patient hypothyroid. Confirm with thyroid function tests and thyroid scintigraphy (technetium or I-123 scan). If it is the only functioning thyroid tissue, either leave it in place and treat with thyroid hormone, or excise and commit to lifelong thyroid replacement.
Pathology from the excised cyst shows papillary thyroid carcinoma
Papillary carcinoma in a thyroglossal duct cyst occurs in ~1% of cases. If the Sistrunk procedure was performed with complete excision and the remaining thyroid gland is normal on ultrasound, some experts consider the Sistrunk adequate. If there are suspicious thyroid nodules, total thyroidectomy is indicated. RAI ablation may be considered depending on the extent of disease.