CERVICAL THYMIC CYSTS - CT APPEARANCE OF 2 CASES INCLUDING A PERSISTENT THYMOPHARYNGEAL DUCT CYST

The differential diagnosis of cervical cysts in children includes comm on entities such as branchial cleft cysts, thyroglossal duct cysts, an d cystic hygromas, Congenital thymic cysts are uncommon and often misd iagnosed as either branchial cleft cysts or cystic hygromas, However, they may have an appearance on CT that can be characteristic, The cour se of the descent of embryologic thymic tissue in the neck to the medi astinum indicates the potential site of deposition of an ectopic cervi cal thymic cyst. In a child, a cystic lesion that has an intimate rela tionship to the carotid sheath is likely to be a thymic cyst. Of the a pproximately 100 cases of vestigial cervical thymus or thymic cysts th at have been reported in children, only 5 cases of a persistent thymop haryngeal duct cyst have been described [1-5], In two of these five, t he persistent thymopharyngeal duct cyst was demonstrated by CT [1, 2]. We report one additional case of a cervical thymic cyst and one case of a persistent thymopharyngeal duct cyst both depicted by CT.