Objectives: Concurrent intraductal papillary-mucinous neoplasm (IPMN) and autoimmune pancreatitis (AIP) was observed in a patient (index case) at our institution. Cases of coincidental IPMN and type 1 AIP and concurrent ductal adenocarcinoma (PDAC) and AIP have been previously reported. In this study we evaluate the hypothesis that IPMN elicits an IgG4 response.
Methods: Twenty-one pancreases (including the index case) with IPMN resected at our institution were studied. H&E stained slides were reviewed and blocks of peritumoral pancreas were immunostained with IgG4 to look for IgG4-positive plasma cells.
Results: We found evidence of variable IgG4 overexpression in 4/21 (19%) of IPMN. These included the index case and three others without stigmata of AIP.
Conclusion: A small subset of pancreatic neoplasms including intraductal papillary-mucinous neoplasms (IPMN) is associated with an IgG4 autoimmune response that sometimes progresses to peritumoral type 1 AIP and less often to diffuse AIP and IgG4-related systemic disease.
Keywords: AIP; Autoimmune pancreatitis; IPMN; IgG4; Intraductal papillary-mucinous neoplasm.
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