IgG4-Related Periaortitis Initially Suspected of Being an Aortic Intramural Hematoma in the Ascending Aorta

Immunoglobulin G4-related disease (IgG4-RD) can affect various organs, including the cardiovascular system. In this study, we described the case of a 72-year-old man with periaortitis both in the ascending and terminal aorta related to IgG4-RD. He presented with swelling in the left leg. Computed tomography (CT) showed increased wall thickness of the ascending aorta and retroperitoneal fibrosis, which, in turn, caused deep vein thrombosis. Using positron emission tomography-computed tomography, the patient was diagnosed with IgG4-RD in the aorta. Although it was difficult to distinguish intramural hematoma (IMH) from IgG4-related periaortitis, treatment with steroids has dramatically improved his periaortitis. IgG4-related periaortitis should be differentiated from IMH due to their similar morphologies.