Thymic cyst secondary to cervical irradiation: a complication of treated laryngeal cancer.

This report demonstrates a thymic cyst arising in association with cervical irradiation for laryngeal carcinoma; a process not previously described. Thymic cysts are rare anterior mediastinal masses which have many etiologies, though an increased incidence of thymic cysts in association with Hodgkin's disease has been reported. This association was thought to be related to either mediastinal irradiation or cystic changes within a thymic focus of Hodgkin's disease. This case supports the theory that at least some thymic cysts arise secondary to irradiation.