Congenital Lateral Pharyngeal Diverticulum

Pharyngeal diverticula may be congenital or acquired. The congenital variety are rare, only about 20 cases having been reported. Embryologically they represent branchial cleft remnants and connect with the pharynx. No fistula is seen in the neck. The communications with the pharynx usually have very narrow openings and may not be obvious on laryngoscopy. The site of entry into the pharynx depends on the embryological branchial cleft of which the cyst is the remnant. The most common branchial cleft vestiges seen clinically derive from the second cleft and present as the well-known branchial fistula with its tiny opening in the neck. These may or may not be complete fistulous communications entering the pharynx in the tonsillar fossa. Third and fourth cleft vestiges less commonly give rise to externally communicating tracts and are more likely to be the source of the true congenital lateral pharyngeal diverticulum (Fowler, 1962). Typically connections from these lie close to or enter the pyriform fossa, which is derived from the third and fourth pouches.