A diagnostic strategy to distinguish autoimmune pancreatitis from pancreatic cancer

Clin Gastroenterol Hepatol. 2009 Oct;7(10):1097-103. doi: 10.1016/j.cgh.2009.04.020. Epub 2009 May 4.


Background & aims: Autoimmune pancreatitis (AIP) and pancreatic cancer (PaC) have similar presentations; a diagnostic strategy is needed to distinguish the 2 diseases.

Methods: We compared computed tomography images (for pancreas and other organ involvement), serum IgG4 levels, histology data, and the response to steroids between patients with AIP (n = 48) and those with PaC (n = 100).

Results: Pancreatic imaging findings stratified patients into 3 groups. Group 1 was highly suggestive of AIP, with diffuse pancreatic enlargement without group 3 features (n = 25, 100% AIP). Group 2 was indeterminate, with normal-sized pancreas or focal pancreatic enlargement without group 3 features (n = 20, 75% AIP). Group 3 was highly suggestive of PaC, with presence of >1 low-density mass, pancreatic duct cutoff, or upstream pancreatic atrophy (n = 103, 92% PaC). Although all patients in group 1 had AIP, only 20 of the 25 patients had increased serum IgG4 levels and/or other organ involvement. Of the patients in groups 2 and 3 who did not have cancer, all those with serum IgG4 levels >2-fold the upper limit of normal or a combination of increased serum IgG4 levels and other organ involvement (n = 15) had AIP. In AIP subjects without supportive serologic evidence or other organ involvement (n = 14), diagnosis required pancreatic core biopsy (n = 7), steroid trial (n = 5), or resection (n = 2).

Conclusions: PaC can be distinguished from AIP by pancreatic imaging, measurement of serum IgG4 levels, and determination of other organ involvement. However, a pancreatic core biopsy, steroid trial, or surgery is required for diagnosis in approximately 30% of patients with AIP.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Aged
  • Anti-Inflammatory Agents / therapeutic use
  • Autoimmune Diseases / diagnosis*
  • Diagnosis, Differential
  • Female
  • Histocytochemistry
  • Humans
  • Image Interpretation, Computer-Assisted
  • Immunoglobulin G / blood
  • Male
  • Middle Aged
  • Pancreas / diagnostic imaging
  • Pancreas / pathology
  • Pancreatic Neoplasms / diagnosis*
  • Pancreatitis / diagnosis*
  • Radiography
  • Steroids / therapeutic use
  • Tomography


  • Anti-Inflammatory Agents
  • Immunoglobulin G
  • Steroids