A 45-year-old man with a painless neck mass undergoes CT of the neck with contrast. The mass is a well-defined cystic lesion with a thin enhancing wall located at the angle of the mandible, anterior to the sternocleidomastoid muscle, lateral to the carotid sheath, and posterior to the submandibular gland. No solid components are seen. What is the most likely diagnosis?

• A Thyroglossal duct cyst
• B Dermoid cyst
• C Cystic hygroma
• D Second branchial cleft cyst ✓

Explanation

A second branchial cleft cyst is the most common branchial anomaly, classically presenting as a cystic neck mass along the anterior border of the sternocleidomastoid muscle at the level of the mandibular angle, lateral to the carotid sheath, and posterior to the submandibular gland. These cysts are lined by squamous epithelium and arise from incomplete obliteration of the second branchial cleft. Thyroglossal duct cysts are midline or paramidline and move with swallowing. Cystic hygromas are multiloculated and occur in the posterior triangle. Dermoid cysts are midline and contain fat density.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.