Epicardial Cyst Originating from Right Ventricle
A 64-year-old female who had hypertension was admitted with a growing asymptomatic mediastinal mass that was detected incidentally through a medical checkup. The mass had increased in size and appeared to be about twice as large as it had been 2 years earlier according to the chest radiographs. Chest radiography showed a round mass in the middle mediastinum abutting with the left cardiac border (). The blood pressure was 125/79 mmHg and the heart rate was 80 beats/min without any cardiac murmurs and with clear breathing sounds. Laboratory tests including a complete blood cell count, electrolytes, chemicals, and coagulation tests were unremarkable. Her electrocardiography showed a normal sinus rhythm. On 2-dimensional echocardiography, the large cystic mediastinal mass (5.0×4.7 cm) was adjacent to the main pulmonary artery. Computed tomography (CT) showed a 5-cm well defined homogenous enhancing mass attached to the anterolateral wall of the left ventricle and mildly compressing the main pulmonary artery (). Although the left anterior descending coronary artery was displaced posteriorly by the mass, the reconstructed CT image revealed that it had no significant narrowing (). Magnetic resonance imaging (MRI) showed a mildly enhancing cystic lesion with heterogeneous signal intensity on tumor 1 (T1), and tumor 2 (T2) images suggesting the possibility of a neurogenic tumor such as schwannoma with hemorrhagic degeneration ().\nA median sternotomy was used and we could see the mass was attached to the epicardium of the right ventricle after pericardiotomy (). Dissection of the mass was difficult because of severe adhesion and proximity to the left anterior descending coronary artery. We decided to apply cardiopulmonary bypass because of a risk of perforation of the right ventricle. The ascending aorta and single right atrial cannulation was used. Except for the right ventricular adhesion, excision of the mass along the layer was simple. The cyst was connected to the epicardium through a feeding vessel. During dissection of the mass, the feeding vessel was cut accidentally, and the mass collapsed immediately. The mass was filled with a blood-like fluid. After ligation using double silk tying and clipping, the cystic mass was removed.\nThe gross pathologic specimen was a unilocular cyst (5.5×5×2.8 cm) of which the outer surface was yellowish white with multifocal hemorrhage and the inner surface was yellowish white with multiple yellowish pigments without a solid portion. A microscopic section showed membranous fibrous tissue with calcification and histiocytic infiltration () that looked like a vessel wall with atherosclerotic changes. The patient was discharged on the 6th post-operative day without any complications. The follow-up 2-dimensional echocardiography did not show any other abnormalities.