What is a cervical cyst?

• A. A patent cervical sinus that develops a cystic lesion along the border of the sternocleidomastoid muscle; may or may not be fistulated
• B. A midline thyroglossal duct cyst
• C. A branchial cleft cyst near the angle of the mandible
• D. A dermoid cyst at the floor of the mouth

Answer: (A)

A cervical cyst is a congenital lesion arising from persistence of the cervical sinus, a transient space formed during the development of the branchial apparatus. When this sinus fails to involute, it can leave a cystic structure in the lateral neck, typically along the anterior border of the sternocleidomastoid muscle, and it may have a fistulous tract to the skin.

The description that matches this best is a persistent cervical sinus that develops a cystic lesion along the border of the sternocleidomastoid, with or without a fistula. This differentiates it from midline thyroglossal duct cysts, which lie in the midline and move with tongue protrusion, and from dermoid cysts of the floor of the mouth, which are midline and not lateral. First branchial cleft cysts, near the angle of the mandible or ear region, are a related but distinct entity.