Massive benign pericardial cyst presenting with simultaneous superior vena cava and middle lobe syndromes

A 66 year old hypertensive and asthmatic chronic smoker presented with 8 month history of progressively increasing shortness of breath. Examination revealed an anxious, tachycardic woman, breathless at rest with engorged neck veins, purple discolouration of face, swelling of face and neck and wheeze over whole of right chest. A posteroanterior chest X ray showed a large mediastinal mass occupying right middle and lower zones of chest with an atelectatic middle lobe (fig 1). Lateral chest x ray confirmed the anterior location of the mediastinal mass (fig 2). Spirometry demonstrated FEV1 0.84 L (47% predicted), FVC 2 L (92% predicted), VC 2 L (92% predicted), FEV1/FVC 42%, PEF120 L/min. Flexible bronchoscopy showed normal appearances of the tracheobronchial tree. CT Thorax showed a smooth ovoid mass in the right anterior lower chest abutting the chest wall, diaphragm and the right pericardium, and which showed a thin slightly higher density wall and low density contents with average CT number of 10, consistent with fluid (fig 3). There was no mediastinal lymphadenopathy. An MR scan showed a large cystic mass 11 × 11 × 8 cm in the right anterior hemithorax, having the signal characteristics of neither a vascular lesion nor a lipoma, in direct contact with pericardium and, therefore, quite likely to be a pericardial cyst, and causing external compression of right hilum, right atrium and SVC (figs 4 and 5). Blood examination revealed normal FBC, U&E, LFTs, calcium and glucose and a slightly increased ESR at 25 mm/hr. Echocardiography revealed an extracardiac mass abutting the right atrium and ventricle and TOE, on operation table, confirmed the presence of a huge anterior mediastinal mass (Fig 6).At median sternotomy, there was a 15 × 10 × 8 cm cyst, adherent to the pericardium loosely, overlying SVC, right atrium, right pulmonary hilum, the middle lobe and the anterior basal segment of the lower lobe of lung and compressing all the above structures (Fig 7). The large cy