Endovascular Repair of a False Aneurysm Developing from IgG4-Related Periaortitis during Corticosteroid Therapy.

Immunoglobulin G4 (IgG4)-related disease is a systemic autoimmune disease that can affect various organs. Corticosteroid therapy is generally an effective treatment; however, IgG4-related aortic lesions pose a risk of aortic rupture related to corticosteroid use. Here, we report a case of IgG4-related periaortitis complicated with a false aneurysm during corticosteroid therapy. Although endovascular repair was successfully performed, autoimmune pancreatitis and sclerosing cholangitis emerged after surgery. The multiple lesions associated with IgG4-related disease were resolved through continuous corticosteroid therapy. Our case suggests that both appropriate surgical intervention and continuous corticosteroid therapy are essential for the treatment of IgG4-related periaortitis.