ABSTRACT
Background: Pericardial cysts are rare and represent the third most common cystic mass of the mediastinum. The majority are asymptomatic and detected as incidental findings; however, they can be symptomatic and associated with life-threatening complications such as bronchial compression, congestive heart failure, cardiac tamponade, or even sudden death. Case summary: We present a rare case of a haemorrhagic pericardial cyst with subtotal compression of the right side of the heart. A symptomatic male patient was referred due to progressive dyspnoea, signs of congestive heart failure for four months, and a transthoracic echocardiogram showing subtotal compression of the right heart side; the diagnosis was confirmed with thoracic computer tomography imaging and was removed surgically. Discussion: Pericardial cysts are asymptomatic and benign in the majority of cases; however, they can be associated with life-threatening complications. Thus, regular follow-up is recommended, and in a minority of cases, minimal invasive intervention or surgery could be imperative.