Fourth branchial cleft cyst.

Remnants of the fourth branchial arch are uncommon clinical entities. They may present in either the neck or chest in association with aortic arch development. They are encountered more frequently in younger individuals as an asymptomatic left-sided neck mass, recurrent neck abscess or suppurative thyroiditis. In view of the rarity of this lesion, we thought it worthwhile to present the case of a 25-year-old female with a diagnosed fourth branchial cleft cyst in her left lower neck. The embryology and management of these cases is discussed.