Original articles—liver, pancreas, and biliary tract
A Diagnostic Strategy to Distinguish Autoimmune Pancreatitis From Pancreatic Cancer

https://doi.org/10.1016/j.cgh.2009.04.020Get rights and content

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.

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Section snippets

Methods

The study was approved by Mayo Foundation Institutional Review Board.

Comparison of Demographics and Clinical Presentation

AIP patients were younger (mean age, 61 ± 16 vs 67 ± 12 years, P = .006) and more likely to be male (85% vs 57%, P < .001) compared with PaC patients. AIP patients presented with obstructive jaundice more often than PaC patients (87.5% vs 49%, P < .001). However, a similar proportion of AIP and PaC patients had abdominal pain (58% vs 50%), severe abdominal pain (15% vs 10%), back pain (10% vs 6.4%), weight loss of >10 pounds (51% vs 42%), and anorexia (30% vs 21%).

Pancreatic Findings on Computed Tomography Scan

A number of pancreatic

Discussion

In this comparative study of a large number of AIP and PaC patients, we found that CT features can stratify patients into groups that are highly likely to have AIP, those highly likely to have PaC, and those in whom the diagnosis is uncertain. Collateral evidence of AIP in the form of serum IgG4 elevation and other organ involvement can then help diagnose AIP in 70% of patients. However, ∼30% of AIP patients will require pancreatic core biopsy, steroid trial, or surgery to make the diagnosis.

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  • Cited by (314)

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    Conflicts of interest The authors disclose no conflicts.

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