Enormous Aneurysm in Coronary Artery Fistula With Immunoglobulin G4-Related Disease.

We report the first case of coronary artery fistula with aneurysmal change in a patient with immunoglobulin G4-related disease (IgG4-RD). This case revealed concomitant coronary artery dilation, pericardial inflammatory nodules, and coronary-pulmonary fistula aneurysm in addition to several IgG4-RD lesions. Each of these features was located in close proximity to the thickened pericardium. These lesions might result from inflammation of the pericardial space, which extended to the coronary-pulmonary artery vessels, leading to aneurysmal formation. This case will enhance our understanding of the pathological mechanisms of IgG4-RD inflammation.