[Cervical thymic cyst in childhood].

Cervical thymus cyst is a rare cause of neck mass in children. . Approximately 90 cases have been described, and just a few have been published in Spanish literature. They usually appear in early children and are diagnosed as brachial cyst. We report the case of a 6 year old boy with a swelling on the right side of the neck. The swelling had appeared a few months before. Ultrasound examination of a neck mass and MRI showed a cystic mass compatible with possible branchial cyst. Excision of the tumor was performed. Pathology showed cystic mass with remains of thymic tissue in the walls, so the final diagnosis was cervical thymic cyst.