Multilocular cervical thymic cyst: an unusual neck mass in children.

Thymic cysts are usually considered uncommon lesions in the differential diagnosis of neck masses. Approximately 100 cases have been reported to date and most of these cases have occurred asymptomatically. Herein, the authors report a 4-year-old boy with cervical thymic cyst, which was misdiagnosed preoperatively as conglomerated lymph nodes. The correct diagnosis was made after surgical excision and through determination of specific histopathological findings of the thymic cyst. The etiologic theories, differential diagnosis and the treatment of thymic cysts are discussed.