The ultrasound image in Figure 1 shows a large cystic mass anterior to the thyroid gland (arrowheads). The contrast-enhanced CT scan (Figure 2) demonstrates the same predominantly midline cystic mass extending anteriorly to the thyroid gland and under the strap muscles, without evidence of ectopic thyroid tissue. The findings are consistent with the diagnosis of a thyroglossal duct cyst.
Thyroglossal duct cysts are the most common cause of a midline neck mass. They usually occur between the hyoid bone and the thyroid gland and represent up to 70% of congenital neck anomalies. Thyroglossal duct cysts are second only to lymphadenopathy as the most common cause of a neck mass.
The cysts usually appear in the midline and can be present anywhere along the line of fetal descent from the foramen cecum to the level of the thyroid gland. From an embryologic perspective, the thyroid gland develops during the third week of life as an outgrowth of the floor of the primitive pharynx. The primitive thyroid then descends from the foramen cecum to its mature position in the anterior neck through the thyroglossal duct. The thyroglossal duct is normally resorbed by 7-10 weeks of fetal life.
Abnormal persistence of the thyroglossal tract accompanied by mucus production from the endothelial lining of the tract leads to the development of a thyroglossal duct cyst. Approximately 7% of the population has thyroglossal duct remnants, and the distribution is equal among males and females. The cysts are usually found in children or adults younger than 30 years, but they can develop in adults of any age. Recently, numerous older patients, including patients in their 80s and 90s, have presented with thyroglossal duct cysts.
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Cite this: Jitendra Gohil, Pramod Gupta. A 45-Year-Old Man With Gradual Neck Swelling - Medscape - Nov 30, 2016.