Neck rule 6 :Branchial cleft cyst

There is a well circumscribed low attenuating, likely cystic, mass located posterior to the submandibular gland, lateral to the carotid space, and anteromedial to the sternocleidomastoid muscle. The mass demonstrates slight rim enhancement, with mild inflammation of the adjacent fat.

Differential diagnosis of that radiological appearance:
- Infected second Branchial cleft cyst
- Necrotic malignant adenopathy
- Lymphangioma
- Thymic cyst