A case of incidentally detected IgG4-related sclerosing disease involving inflammatory abdominal aortic aneurysm and autoimmune pancreatitis.

A 59-year-old asymptomatic man was incidentally found to have a periaortic mass and an elevated serum amylase level during his medical check-up. Additional findings, such as infiltration of immunoglobulin G4 (IgG4)-producing plasma cells in the mass lesion, elevation of serum IgG4 (1000 mg/dl), and pancreatic duct narrowing as evidenced on a magnetic resonance cholangiopancreatography scan, confirmed the diagnosis as retroperitoneal fibrosis complicated with autoimmune pancreatitis. The patient responded favorably to steroid treatment before the appearance of symptoms.