To investigate the clinical features of IgG4 related autoimmune pancreatitis (AIP).

Clinical data of 12 patients pathologically diagnosed as IgG4 related AIP in Department of Hepatopancreatobiliary Surgery, Sun Yat-sen Memorial Hospital of Sun Yat-sen University from January 2003 to December 2012 were retrospectively analyzed. The informed consents of all patients were obtained and the ethical committee approval was received. All the patients were males with a mean age of (54±13) years old. All were misdiagnosed as pancreatic head carcinoma and received pancreatoduodenectomy. Data of the clinical manifestations, laboratory, imaging and pathological examinations were collected. The patients were followed up after operations, the treatment and outcome were studied.

The clinical manifestations of the 12 patients were abdominal pain (n=7), jaundice(n=7), emaciation(n=6) and no obvious symptom (n=1). Three cases were combined with diabetes, 1 case with chronic sialadenitis of submandibular gland. The patient's blood and urine amylase were normal. Blood gamma-glutamyl transpeptidase (GGT) increase was observed in 12 cases. Mild increase of carbohydrate antigen 19-9 (CA19-9) was observed in 9 cases. Cancer antigen (CA) 125 increase was observed in 3 cases, and carcinoembryonic antigen (CEA) increase in 2 cases. Through contrast-enhanced CT, partial pancreatic head enlargement was observed in 11 cases, in which 3 cases were observed combining with mild expansion of pancreatic duct. Through magnetic resonance imaging (MRI), sausage-like change of pancreas body was observed in 4 cases, peripancreatic sheath-like change in 5 cases. Through magnetic resonance cholangiopancreatography (MRCP), stenoses in the pancreatic duct of pancreatic head segment and distal common bile duct were observed including 4 cases of mild expansion in the distal pancreatic duct. Local invasion was not observed by imaging examinations. Lymphoplasmacytic sclerosing pancreatitis was determined by pathological examination. Positive expression of IgG4 was observed by immunohistochemistry. Twelve cases suffered from discontinuous abdominal pain after operations, in which 7 cases needed acesodyne. One case relieved after using prednisone.

Clinical manifestations of IgG4 related AIP are similar to pancreatic carcinoma and can be misdiagnosed as pancreatic carcinoma easily. The main clinical features are mild increase of blood CA19-9. Partial pancreatic head enlargement, pancreas body sausage-like change, peripancreatic sheath-like change, and no local invasion are observed by imaging examinations. Lymphoplasmacytic sclerosing pancreatitis is determined by pathological examination. Positive expression of IgG4 is observed by immunohistochemistry. Adrenocortical hormone treatment is effective.