Benign thymic cyst following mantle radiotherapy for Hodgkin's disease.

The case history of a patient who was treated for Stage IA Hodgkin's disease involving the left supraclavicular region is presented. Shortly after mantle field radiation therapy she developed a mass in the anterior mediastinum. Histological examination of the lesion revealed it to be a benign cyst of the thymus. We consider it important that the possibility of the existence of such a benign growth be considered when a mediastinal mass appears in a patient treated for Hodgkin's disease, before more intensive tumour therapy is given.