Thyroglossal Duct Cyst

This sagittal ultrasound image (left is superior) shows a cystic structure just below the level of the hyoid bone. A small beak of the cyst can be seen passing superiorly over the hyoid. The patient is a 37 year-old female who presented with a painful, tender midline neck lump.
Thyroglossal duct cyst usually presents as a midline neck mass, usually at the level of the hyoid bone. 50% present before age 10, the remainder presenting usually in young adulthood. The thyroglossal duct forms as the thyroid gland descends from the foramen cecum at the base of the tongue. Thyroglossal duct cysts are typically lined by stratified squamous epithelium or ciliated pseudostratified columnar epithelium. Ectopic thyroid tissue is seen in 62% of cases. The cyst is located just below the hyoid bone in 65%, at the hyoid in 15%, and suprahyoid in 20%. The cyst is usually 2-4cm in diameter. Sagittal T2-weighted MRI may be useful to demonstrate the superior course of a suprahyoid cyst. Treatment involves surgical excision of the entire squamous epithelial lining. Carcinoma may develop in thyroglossal duct cyst (1% of cases) - interestingly this is most commonly papillary cell thyroid carcinoma type.
Reference: Harnsberger HR. Handbook of Head and Neck Imaging. 2nd edition. Mosby 1995.
Credit: Dr Laughlin Dawes
http://www.radpod.org