Abstract

The congenital cyst is a rare tumor which can be situated in the neck or the mediastinum. Since Pollosson and Piery published their first case of cervical thymic cyst in 1901, approximately 40 cases have been recorded in the world literature. Correct preoperative diagnosis of this cystic mass has seldom been made. About two-thirds occur in the first decade of life and most of the remainer in the second in contrast to the common branchial cysts that occur after the second decade. Males are affected twice as ofen as females. They are believed to develop in remnants of thymic tissue which have failed to descend from the third branchial pouch into the mediastinum in the 6th to 8th weeks of embryonic life.