Branchial cleft cysts

Branchial cleft cysts are the most common congenital cause of a neck mass. They are epithelial cysts, which arise anterior to the superior third of the sternocleidomastoid muscle from a failure of obliteration of the second branchial cleft in embryonic development. The second arch grows caudally and, ultimately, covers the third and fourth arches. The buried clefts become ectoderm-lined cavities, which normally involute. Occasionally this process is arrested and the entrapped remnant forms an epithelium-lined cyst sometimes with a sinus tract to the overlying skin. Many branchial cleft cysts are asymptomatic but some may become tender, enlarged, or inflamed, or they may develop abscesses that rupture, resulting in a purulent draining sinus to the skin or pharynx – surgery is indicated in these cases.