Autoimmune pancreatitis type-1 associated with intraduct papillary mucinous neoplasm: report of two cases

Chronic pancreatitis lesions usually embrace both intraduct papillary mucinous neoplasm (IPMN) and pancreatic ductal adenocarcinoma (PDAC). Patients at genetically-determined high risk of PDAC often harbor IPMN and/or chronic pancreatitis, suggesting IPMN, chronic pancreatitis and PDAC may share pathogenetic mechanisms. Chronic autoimmune pancreatitis (AIP) may also herald PDAC. Concurrent IPMN and AIP have been reported in few patients. Here we describe two patients with IPMN who developed type-1 AIP fulfilling the Honolulu and Boston diagnostic criteria. AIP diffusively affected the whole pancreas, as well as peripancreatic lymph nodes and the gallbladder. Previous pancreatic resection of focal IPMN did not show features of AIP. One of the patients carried a CFTR class-I mutation. Of notice, serum IgG4 levels gradually decreased to normal values after IPMN excision. Common risk factors to IPMN and AIP may facilitate its coincidental generation.