Images in clinical medicine. Benign mediastinal teratoma.

A 23-year-old male Marine recruit passed out while bending over after a 2.4-km (1.5-mile) run. Chest radiography showed a mass in the anterior mediastinum (Panel A, arrow). His medical history was notable only for the removal of a benign thyroid cyst at the age of 12 years. He reported no use of medications or tobacco and no drug allergies. The physical examination and initial laboratory studies were unremarkable except for prominent varicosities noted on his chest (Panel B). Contrast-enhanced computed tomography of the chest revealed a large anterior mediastinal mass with fluid, fat, and calcific densities (Panel C, arrow) that . . .