Cardiac tamponade caused by intrapericardial yolk sac tumor in a boy.

Yolk sac tumor rarely involves the pericardium. A 17-year-old boy had a mediastinal mass leading to total obstruction of the superior vena cava with cardiac tamponade and pleural effusion. Further imaging studies and biopsy showed that the origin was a yolk sac tumor. After surgery and adjuvant chemotherapy, no recurrence was noted during a follow-up of 20 months. This report describes the magnetic resonance imaging characteristics of pericardial yolk sac tumor.