DOI: https://doi.org/10.36347/sjmcr.2025.v13i06.007

Pages: 1329-1334

Introduction: Cystic tumors of the atrioventricular (AV) node are exceptionally rare benign cardiac neoplasms with the potential to disrupt cardiac conduction, leading to complete heart block or sudden cardiac death. Due to their rarity and nonspecific clinical presentation, diagnosis often relies on multimodal imaging and histological confirmation. Case Presentation: We reported a case of 38-year-old woman who presented with an incidental complete heart block during hospitalization for community-acquired pneumonia. Imaging studies revealed a well-defined right atrial mass adjacent to the interatrial septum. Cardiac magnetic resonance imaging suggested a fibroma; however, intraoperative findings revealed a cystic, multi-septated mass in the triangle of Koch. The patient underwent successful minimally invasive right atrial mass excision. Histopathological examination confirmed a benign cystic tumor of the AV node. The patient recovered uneventfully and remained stable pending permanent pacemaker implantation. Conclusion: AV node cystic tumors, though benign, carry a high risk of conduction abnormalities and sudden cardiac death. Early detection and surgical intervention are crucial. This case highlights the utility of multimodal imaging and supports the feasibility and safety of minimally invasive cardiac surgery for tumor resection.