A 28-year-old woman presents with a smooth, fluctuant, non-tender swelling in the anterior triangle of the neck at the level of the carotid bifurcation. It transilluminates brilliantly and moves laterally but not vertically. FNA reveals clear fluid with no cells except occasional lymphocytes. What is the most likely diagnosis?

• A Cystic hygroma (lymphatic malformation)
• B Thyroglossal cyst
• C Dermoid cyst of the floor of the mouth
• D Second branchial cyst ✓

Explanation

Second branchial cysts are the most common branchial anomalies, presenting in young adults as smooth fluctuant swellings at the anterior border of the sternocleidomastoid at the junction of its upper and middle thirds, near the carotid bifurcation. They transilluminate, contain cholesterol crystals in clear fluid, and move horizontally. Cystic hygromas typically present at birth or in infancy, are multilocular, brilliantly transilluminant, and usually in the posterior triangle. Complete surgical excision along the branchial tract is treatment of choice.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.