Thyroglossal Duct Cyst
- Cyst composed of epithelial remnants of the thyroglossal tract as it descends from foramen cecum at tongue base to the lower neck
- Midline neck mass at the level of the thyrohyoid membrane, closely associated with the hyoid bone, within 2 cm of the midline
- Often asymptomatic midline neck mass but can become infected and rapidly increase in size
- Majority are located between thyroid and hyoid, followed by suprahyoid and then suprasternal, and finally intralingual being the rarest location.
- System(s) affected: endocrine; metabolic; skin; exocrine
Most common form of congenital midline cyst in the neck, yet rare to present clinically in neonatal period
- Majority of cases present in patients <30 years old.
- Predominant sex: male = female
Occurs in up to 7% of population
Etiology and Pathophysiology
- Cystic expansion of a remnant of the thyroglossal duct tract
- Incomplete closure of the thyroglossal duct during gestation
- Persistence of the epithelial tract, the thyroglossal duct, during the descent of the thyroid from the foramen cecum to its final position in the anterior neck
- The thyroglossal duct tract usually atrophies and disappears by the 8th to 10th week of gestation.
- Portions of the tract and remnants of thyroid tissue associated with it may persist at any point between the tongue and the thyroid.
- Failure of the thyroglossal duct to atrophy and involute after descent of the thyroid in the 4th to 7th week of gestation
- Hypothesis: lymphoid tissue associated with the tract hypertrophies at the time of a regional infection, thereby occluding the tract with resulting cyst formation
- Usually sporadic; if familial, autosomal dominant is most common mode of inheritance.
- Familial occurrence is extremely rare.
Commonly Associated Conditions
- History of a recent upper respiratory tract infection (URI)
- Ectopic thyroid tissue found in almost half of cysts and rarely associated with ectopic thyroid gland
- Thyroid carcinoma (rare)
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