Branchial arch lesions are a congenital lesion of the neck. These present most commonly as openings (sinuses) but also as cysts. They are caused by the failure of normal fusion of two adjacent branchial arches. They often are present at birth, but a cyst may present later, particularly after an infection. The most common level for this to occur is along the side of the neck. Surgical excision is the management of choice.