Pancreatic ductal adenocarcinoma with autoimmune pancreatitis-like histologic and immunohistochemical features

Hum Pathol. 2014 Mar;45(3):621-7. doi: 10.1016/j.humpath.2013.08.027. Epub 2013 Nov 7.


Autoimmune pancreatitis (AIP) often manifests as a mass lesion causing obstructive jaundice, clinically mimicking pancreatic carcinoma. A diagnosis of AIP may obviate the need for surgical resection, as most patients respond to steroid treatment. However, it is not clear whether these 2 conditions can coexist. In this study, 105 specimens resected for pancreatic ductal adenocarcinoma (PDAC) that also have changes of chronic pancreatitis were examined for features considered to be characteristic of AIP. Of 105 cases of PDAC with changes of chronic pancreatitis, 10 (9.5%) exhibited histologic features of AIP, including exuberant fibrosis, lymphoplasmacytic infiltration, obliterative phlebitis, or granulocytic epithelial lesions. Of these 10 cases, 7 had more than 20 immunoglobulin G4+ plasma cells per high-power field. Of these 7 cases, 5 were analyzed for Kirsten rat sarcoma viral oncogene mutation and SMAD4 expression. Three cases showed K-ras mutation and/or loss of SMAD4 expression in benign AIP-like areas. These findings suggest 2 possibilities: first, AIP-like lesions may occur in a small but significant portion of PDAC cases; second, some PDACs may arise in a background of AIP. Therefore, caution is necessary when making a diagnosis of AIP by needle biopsy of a mass lesion, and patients with a tentative AIP diagnosis should be closely followed up clinically.

Keywords: Autoimmune pancreatitis; IgG4; Pancreatic ductal adenocarcinoma.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Autoimmune Diseases / diagnosis*
  • Autoimmune Diseases / metabolism
  • Autoimmune Diseases / pathology
  • Carcinoma, Pancreatic Ductal / diagnosis*
  • Carcinoma, Pancreatic Ductal / metabolism
  • Carcinoma, Pancreatic Ductal / pathology
  • DNA Mutational Analysis
  • Diagnosis, Differential
  • Female
  • Humans
  • Immunoglobulin G / metabolism
  • Male
  • Middle Aged
  • Pancreatic Neoplasms / diagnosis*
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology
  • Pancreatitis / diagnosis*
  • Pancreatitis / metabolism
  • Pancreatitis / pathology
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins p21(ras)
  • Smad4 Protein / metabolism
  • ras Proteins / genetics
  • ras Proteins / metabolism


  • Immunoglobulin G
  • KRAS protein, human
  • Proto-Oncogene Proteins
  • Smad4 Protein
  • Proto-Oncogene Proteins p21(ras)
  • ras Proteins