A Case of Non-Swelling Autoimmune Pancreatitis with Multiple Pancreatic Pseudocysts

Context Non-swelling autoimmune pancreatitis with multiple pancreatic pseudocysts is very rare. Case report A Seventy-five-year-old man was referred to our hospital for further examination of multiple pancreatic cysts with nodules detected by computed tomography. Endoscopic ultrasound examination showed a pancreatic cyst with a nodule (6.3 mm in diameter) in the pancreatic head and another pancreatic cyst with a nodule (8.7 mm in diameter) in the pancreatic tail, and these cysts were connected to the main pancreatic duct. The patient was clinically diagnosed with branch duct type intraductal papillary mucinous neoplasm of the pancreas. The recent international consensus guidelines indicate that a mural nodule indicates high risk for malignancy and recommend surgical resection of branch duct type intraductal papillary mucinous neoplasm with mural nodule. Therefore, pancreatoduodenectomy and pancreatic body tail resection were performed in our hospital. Histopathological findings showed IgG4-positive plasma cells and obstructive phlebitis. Autoimmune pancreatitis associated with multiple pancreatic pseudocysts was the final diagnosis. Conclusions We encountered a rare case of autoimmune pancreatitis with pseudocyst but not swollen pancreas nor an increase in serum IgG4 level. The correct diagnosis was very difficult before surgical treatment. In clinical cases with various pancreatic cystic lesions, it is necessary to consider autoimmune pancreatitis in the differential diagnosis. Received May 20th, 2016 Accepted June 15th, 2016