Pericardial ectopic thymoma presenting with cardiac tamponade: report of a case.

Ectopic thymoma arising from organs other than the thymus, such as the neck, trachea, thyroid, lung and pericardium, is rare. To date, there have been only seven other cases of pericardial thymoma reported in the English literature. We herein report a case of pericardial ectopic thymoma that presented with cardiac tamponade. A 72-year-old Japanese male noticed body weight gain and leg edema. Chest computed tomography (CT) revealed pericardial effusion and an irregularly shaped mass in the pericardial space compressing the right atrium. He was considered to have cardiac tamponade due to a paracardiac tumor that developed following acute cardiac failure. The intraoperative frozen diagnosis was thymoma. Pericardectomy of the thickened pericardium, tumorectomy and thymectomy via a median sternotomy were performed. The final pathological diagnosis was pericardial ectopic thymoma associated with constrictive pericarditis. The differential diagnosis and complete resection of mediastinal tumors such as this rare case of thymoma are important to obtain a better prognosis, as patients with such tumors often present in a state of shock.