2016 Volume 30 Issue 2 Pages 243-247
A 48-year-old woman with an incidentally diagnosed mediastinal mass was referred to our department. Chest computed tomography showed a well-defined monolocular tumor located in the middle mediastinum, at a site 72 mm from the right subclavian artery and right pulmonary artery. An FDG-PET scan showed no abnormal uptake in the tumor. We performed surgical resection using video-assisted surgery. The tumor was confirmed to be a cystic lesion of the thymus that had spread. A pathological examination revealed fragments of a fibrotic cystic wall with sections of thymic tissue, thus confirming the diagnosis of a thymic cyst. Thymic cysts in the middle mediastinum are extremely rare. We suspected that this was a case involving an ectopic thymus, but the thymus-derived cyst was believed to extend to the middle mediastinum in this disorder.
