Cervical thymic cyst.

Various types of cysts that originate in embryonal remnants may be observed in the neck. Among these, branchial cleft and thyroglossal duct cysts are more commonly observed, whereas thymic cysts are rare. Most patients with a cervical thymic cyst complain of a painless, enlarging mass in the neck. The histopathologic features of thymic cysts are diagnostic. Cystic thymomas, which seem to have a more aggressive clinical behavior in children, should be differentiated from the benign cervical thymic cyst. Thymic cysts most probably arise from embryonic remnants of the thymopharyngeal duct. Our patient had a cervical thymic cyst with neurofibromatosis.