Case report: fourth branchial pouch sinus.

The fourth branchial pouch sinus is a rare anomaly of the branchial arch apparatus. The 31st reported case of a fourth branchial sinus is presented. A thorough understanding of the developmental anatomy of the branchial region is necessary for the detection and treatment of this entity. The diagnosis can be made with a high index of suspicion in patients with recurrent left neck infections by demonstration of a pyriform sinus tract on pharyngoesophagram. Treatment consists of complete surgical excision following exposure of the entire course of the sinus tract including its insertion into the apex of the pyriform sinus.