Branchial Cysts and Sinuses

Abstract

During the fourth to eighth weeks of gestation, four pairs of branchial arches and their intervening clefts and pouches are formed. Congenital branchial cysts and sinuses are remnants of these embryonic structures that have failed to regress completely. Treatment of branchial remnants requires knowledge of the related embryology. The first arch, cleft, and pouch form the mandible, the maxillary process of the upper jaw, the external ear, parts of the Eustachian tube, and the tympanic cavity. Anomalies of the first branchial pouch are rare. Sinuses typically have their external orifice inferior to the ramus of the mandible. They may traverse the parotid gland, and run in close vicinity to the facial nerve in the external auditory canal. Cysts are located anterior or posterior to the ear or in the submandibular region. They must be distinguished from preauricular cysts and sinuses, which are ectodermal remnants from an aberrant development of the auditory tubercles, tend to be bilateral, and are localized anterior to the tragus of the ear. These sinuses are blind, ending in close vicinity of the external auditory meatus.