Fig. 1

Chest computed tomography and positron-emission tomography showing the characteristics of the anterior mediastinal lesion. a Chest computed tomography scan shows a capsulated cystic lesion in the anterior mediastinum and a nodular lesion (arrow) on the capsule inside the cystic lesion wall. b The nodular lesion (arrow) exhibits strong enhancement after the intravenous administration of contrast material. c Positron-emission tomography shows no significant ¹⁸F-fluorodeoxyglucose accumulation in the nodular lesion (arrow)