Spontaneous regression of a pancreatic head mass and biliary obstruction due to autoimmune pancreatitis.

BACKGROUND: Autoimmune pancreatitis is an evolving entity. METHODS: A patient who had spontaneous regression of a pancreatic head mass and biliary obstruction due to autoimmune pancreatitis is presented. RESULTS: A 58-year-old diabetic woman with jaundice was referred for pancreatic head carcinoma diagnosed by magnetic resonance imaging (MRI). At laparotomy, a pancreatic head mass (4 x 3 cm) that involved the transverse mesocolon and two other hard masses (1 cm) in the pancreatic body and tail were found. The gallbladder was palpated as a hard tumor mass. Frozen section examination of the gallbladder and pancreatic biopsies revealed cholecystitis and pancreatitis with lymphoplasmacytic infiltration. The common bile duct was brittle and unsuitable for anastomosis. Starting 1 month after the operation, drainage from the biliary catheter decreased gradually and stopped. There was no parenchymal lesion on MRI examination in the 2nd postoperative month. Cholangiography from the percutaneous catheter showed flow of contrast agent into the duodenum. Serum immunoglobulin G, G4 and E levels were increased. CONCLUSION: To the best of our knowledge, this is the first report of spontaneous regression of a pancreatic head mass and biliary obstruction due to autoimmune pancreatitis.