Brachial cyst is lined by:-

Brachial cyst is lined by squamous epithelium. A branchial cyst develops from the vestigial remnants of the second branchial cleft, is lined by squamous epithelium and contains thick, turbid fluid. The cyst usually presents in the upper neck in early or middle adulthood and is found at the junction of the upper third and middle third of the sternomastoid muscle at its anterior border. It is a fluctuant swelling that may transilluminate and is often soft in its early stages so that it may be difficult to palpate.