MRI neck shows a cystic lesion at the anterior aspect of the sternocleidomastoid muscle at the junction of the upper and middle thirds, displacing the common carotid artery medially and the SCM laterally. The most likely diagnosis is:

• A Thyroglossal duct cyst
• B Lymphatic malformation (cystic hygroma)
• C Dermoid cyst
• D Second branchial cleft cyst ✓

Explanation

Second branchial cleft cysts are the most common (95%) branchial cleft anomaly, typically located along the anterior border of the SCM at the junction of the upper and middle thirds (Bailey classification Type II). They present as smooth thin-walled cystic lesions displacing the SCM posterolaterally and the carotid vessels medially. Thyroglossal duct cysts are midline or paramidline, moving with swallowing. Cystic hygromas (lymphatic malformations) are multilocular, posterior triangle, and infiltrative.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.