Case report: primary pericardial tumour-challenges in imaging diagnosis and management.

Background: Primary pericardial tumours are exceedingly rare and frequently misdiagnosed due to nonspecific clinical presentations. They may initially manifest through cardiovascular complications such as pericardial effusion, arrhythmias, or embolic events, creating significant diagnostic and management challenges. Case summary: We report a 62-year-old female with a history of dyslipidaemia who was admitted for progressive dyspnoea, mild chest pain, and palpitations. Cardiovascular evaluation revealed new-onset atrial fibrillation, large pericardial effusion, and bilateral pleural effusions. Transthoracic echocardiography and contrast-enhanced computed tomography identified a heterogeneous pericardial mass with invasive features involving the pulmonary artery, complicated by pulmonary artery obstruction. The patient developed cardiac tamponade requiring emergent pericardiocentesis, which drained 550 mL of serous fluid. Cytological analysis of the pericardial fluid suggested a malignant mesenchymal tumour, and subsequent CT-guided biopsy raised strong suspicion for a primary pericardial sarcoma, pending immunohistochemical confirmation. The patient was managed with anticoagulation, rate control for atrial fibrillation, supportive therapy, and multidisciplinary consultation, leading to a planned oncologic treatment strategy. Conclusion: This case highlights the pivotal role of cardiology in recognizing occult malignancy presenting with acute cardiovascular manifestations, the diagnostic complexity of primary pericardial tumours, and the importance of multimodal imaging, histopathology, and multidisciplinary collaboration in emergency and long-term management.