Mass-forming type 2 autoimmune pancreatitis with upstream dilatation of the main pancreatic duct dilatation: a case report

Mass-forming type 2 autoimmune pancreatitis can present with main pancreatic duct strictures and upstream dilatation. Although endoscopic ultrasound sonography-guided fine-needle aspiration cytology is useful for the diagnosis of solid pancreatic masses, preoperative diagnosis of type 2 autoimmune pancreatitis remains challenging. Further studies should be conducted to determine whether "hidden" type 2 autoimmune pancreatitis may be more frequently present and to improve the accuracy of the diagnosis of type 2 autoimmune pancreatitis.