Abstract
Coronary artery aneurysm (CAA) is potentially life-threatening. We describe a case of multiple giant CAAs and a single left gastric artery aneurysm caused by immunoglobulin G4-related disease (IgG4-RD). Our case highlights the significance of assessing IgG4-RD in the diagnosis of CAA and screening for other concurrent cardiovascular involvements. (Level of Difficulty: Intermediate.).