Clinical Summary A 63-year-old man was admitted to the hospital with reports of intermittent dyspnea and palpitation for 3 years. No abnormalities were evident on blood tests. The electrocardiogram showed premature atrial beats. The chest radiograph revealed mild elevation of the left bronchus. Echocardiography showed a large capsular space around the roots of the aorta and main pulmonary artery. The magnetic resonance imaging scan showed a giant mass near the aorta, main pulmonary artery, and left atrium, which severely compressed the vessels. The computed tomographic angiogram confirmed the giant mediastinal mass with dimensions of 7.5 7.0 6.5 cm in the transverse sinus involving the aorta, pulmonary artery, pulmonary veins, and coronary artery (Figure 1 and 2, A). Seven days later, the patient underwent surgery. After the chest was opened through a median sternotomy, the pericardium appeared adhesive and very tense, particularly consistently tense and hard around the roots of aorta and main pulmonary artery. The pericardium was separated, starting from the right ventricle where the surface was less tense. After an incision between the aorta and main pulmonary artery was made, a great deal of flavescent viscous liquid with caseous necrosis flowed out of the mass from the incision (Figure 2, B). The encapsulated wall, which was toughly adherent to the aorta, pulmonary artery, and left atrium, was very thick and hard. The surgeon could not completely excise the wall of mass. A tube was placed into the cavity for drainage. The patient had an uneventful postoperative recovery and was discharged on the seventh postoperative day. The pathologic report showed the mass was fibrous granuloma of tuberculosis. On follow-up, the patient was well without any reports such dyspnea, cough, or palpitation. The body temperature was normal and he constantly took antituberculosis drugs. The postoperative computed tomographic angiogram on a follow-up visit showed that the dimensions of cavity had obviously decreased and the narrowing of pulmonary artery, pulmonary veins, and coronary artery had disappeared.