Multimodality imaging diagnosis of congenital absence of the right-sided pericardium presenting with pseudo-ischemic chest pain: A radiology-focused case report.

Congenital absence of the pericardium (CAP) is a rare thoracic anomaly that is frequently asymptomatic but may mimic ischemic heart disease clinically and on initial evaluation. Its diagnosis relies heavily on imaging, yet characteristic radiologic findings are often overlooked. We present the case of a young adult male whose condition was accurately identified and successfully managed through clinical expertise and comprehensive multimodality imaging. A 22-year-old male presented with recurrent nonexertional chest pain and sinus bradycardia. Initial investigations, including electrocardiography and laboratory tests, were unremarkable. Chest radiography was initially interpreted as normal. Transthoracic echocardiography suggested abnormal cardiac mobility and axis deviation. Cardiac magnetic resonance imaging (MRI) confirmed complete right-sided and partial left-sided pericardial absence. Retrospective review of chest X-ray demonstrated the classic "Snoopy sign." Cardiac stress testing showed no inducible ischemia. The patient was managed conservatively with complete symptom resolution. This case highlights the critical role of multimodality imaging in diagnosing congenital absence of the pericardium (CAP) and emphasizes the importance of recognizing subtle radiographic signs. Early radiologic identification can prevent misdiagnosis and unnecessary interventions. Radiologists should maintain a high index of suspicion when encountering unexplained cardiac displacement or abnormal cardiac mobility. A structured diagnostic approach incorporating both clinical reasoning and advanced imaging is essential to help delineate anatomical abnormalities and exclude ischemia, enabling appropriate management decisions.