The etiology of lateral cervical cysts in infancy is complex. The cyst
s are congenital in origin and are derived from the third or fourth br
anchial apparatus. The authors describe two cases of congenital latera
l cervical cysts with an internal opening in the pyriform sinus and po
ssible origin in the third branchial arch. The embryology, clinical pr
esentation, and operative management of this condition is reviewed. Co
pyright (C) 1998 by W.B.Saunders Company.