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 are most commonly located inferiorly to the hyoid bone in the midline or slightly to the side. 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 composition of the cyst is thick mucous material lined with secreting columnar or squamous epithelium. The cyst is surrounded by a thick fibrous capsule. 

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 noted by the parent or during a routine examination.
2. Cysts that are lower in the neck tend to be more off the midline because of the presence of the thyroid cartilage.
3. If the cyst is attached to the base of the tongue or the hyoid bone, it will move with 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. 

1. Dermoid cyst
2. Lymph node
3. cystic hygroma
4. branchial cyst
5. lipoma
6. laryngocele

1. Infected cyst treated with antibiotic to cover gram positive organism including staphylococcus, warm compresses, and either needle aspiration or I&D 
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. It is not recommended to do thyroid scan prior to surgery because an ectopic thyroid gland is a rare occurrence.
3. Often have to remove part of the hyoid bone during surgery.
3. Recurrences of the cyst in about 5% of cases. 
4. Presence of carcinoma present within a cyst is <1%.

1. Girard, Mark, and DeLuca, Salvatore. Thyroglossal Duct Cyst. American Family Practice. Sept. 1990
2. Brousseau V et al. Thyroglssal Duct Cysts-Presentation and Management in Children versus Adults. International Journal of Pediatric Otorhinolaryngology. Dec. 2003