Intrapericardial Mature Cystic Teratoma.

Mediastinal masses are an uncommon and encompass a wide variety of lesions. Their diagnosis and management are often dependent upon the radiographic features, symptoms, and serologies. Germ cell tumors are exceedingly rare in this location. This case report describes a mediastinal mass in a 37-year-old man who presented with occasional chest pain. Pathology revealed an intrapericardial mature cystic teratoma that arose from the adventitia of the aorta. Mature teratomas are most commonly found outside the pericardium. This report describes the exceedingly rare diagnosis of a mature cystic teratoma arising from the aortic adventitia.