Third branchial cleft cyst

Case contributed by Mohammad A. ElBeialy
Diagnosis probable


Left lower posterior neck swelling for 15 years. Pain and further swelling for a week.

Patient Data

Age: 50 years
Gender: Male

A well-defined ovoid, thick-walled, cystic mass lesion is seen in the posterior triangle behind the left sternocleidomastoid muscle, measuring ~4.2 X 4.6 X 5.3 cm in its orthogonal dimensions. The lesion shows low T1, high T2 / FLAIR signal intensity.  The mass is seen abutting and mildly indenting the left sternocleidomastoid muscle anteriorly and the scalene muscles posteriorly. The lesion is abutting the carotid artery medially as well as having subcutaneous location laterally.

Enlarged bilateral cervical lymph nodes.

Case Discussion

Left posterior triangle cystic mass lesion; impressive of an infected third branchial cleft cyst (BCC) rather than a unilocular lymphangioma with bilateral cervical lymphadenopathy.

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