A case of autoimmune pancreatitis associated with retroperitoneal fibrosis.

CONTEXT Autoimmune pancreatitis is characterized by diffuse enlargement of the pancreas, diffuse irregular narrowing of the main pancreatic duct, severe lymphoplasmacytic infiltration and fibrosis of the pancreas. Retroperitoneal fibrosis may occasionally be associated with autoimmune pancreatitis. CASE REPORT We report a 77-year-old man with autoimmune pancreatitis associated with retroperitoneal fibrosis. Abdominal ultrasonography and computed tomography demonstrated diffuse enlargement of the pancreas and a capsule-like rim. Furthermore, a retroperitoneal mass was recognized anterior to the abdominal aorta. Antinuclear antibody, IgG and IgG4 values were elevated. Therefore, this patient was diagnosed as having autoimmune pancreatitis associated with retroperitoneal fibrosis. We performed steroid therapy using prednisolone. After 4 weeks, both IgG and IgG4 values decreased and both the swelling of the pancreas and also the retroperitoneal mass were obviously diminished. CONCLUSION This is a rare case of autoimmune pancreatitis associated with retroperitoneal fibrosis.