A cystic structure on the lateral neck at the angle of the mandible under the sternocleidomastoid muscle, formed from the remnant of the 2nd brachial cleft, is which?

A cystic structure on the lateral neck at the angle of the mandible under the sternocleidomastoid muscle, formed from the remnant of the 2nd brachial cleft, is which?

• A. Thyroglossal Duct Cyst
• B. Brachial Cleft Cyst
• C. Simple cyst
• D. Dermoid Cyst

Answer: (B)

This is a branchial cleft cyst, specifically from persistence of the second pharyngeal (branchial) cleft. It classically presents as a painless, well-defined cystic mass in the lateral neck along the anterior border of the sternocleidomastoid near the angle of the mandible. The second cleft cyst is the most common branchial cleft anomaly and often has a tract that can connect toward the tonsillar fossa, explaining its lateral neck location. This helps distinguish it from a thyroglossal duct cyst, which is midline and moves with swallowing or tongue protrusion, and from a dermoid cyst, which is usually midline or subcutaneous and not tied to the lateral neck cleft lineage. On ultrasound the lesion is typically a simple or mildly complex cyst in the lateral neck.

This is a branchial cleft cyst, specifically from persistence of the second pharyngeal (branchial) cleft. It classically presents as a painless, well-defined cystic mass in the lateral neck along the anterior border of the sternocleidomastoid near the angle of the mandible. The second cleft cyst is the most common branchial cleft anomaly and often has a tract that can connect toward the tonsillar fossa, explaining its lateral neck location. This helps distinguish it from a thyroglossal duct cyst, which is midline and moves with swallowing or tongue protrusion, and from a dermoid cyst, which is usually midline or subcutaneous and not tied to the lateral neck cleft lineage. On ultrasound the lesion is typically a simple or mildly complex cyst in the lateral neck.