Distinguishing Pancreatic Cancer from Autoimmune Pancreatitis

Abstract

Both autoimmune pancreatitis (AIP) and pancreatic cancer frequently present with obstructive jaundice. However, AIP is a rare disease and its diagnosis carries vastly different therapeutic and prognostic implications compared with that of pancreatic cancer. The clinical challenge is to distinguish AIP from pancreatic cancer, because the price of misdiagnosis can be heavy. Recently, two strategies for differentiating AIP from pancreatic cancer were published, one from Japan and the other from the United States. The Japanese strategy relies on cross-sectional imaging, endoscopic retrograde pancreatogram, and serum IgG4. The American strategy uses imaging (CT scan), serology (serum IgG4), and evidence of other organ involvement (on CT scan) as the first tier of tests. If the differentiation cannot be made by these methods, a core biopsy of the pancreas, steroid trial, or surgical resection is recommended. The two strategies reflect differences in clinical practice and local preferences in the use of certain diagnostic tests. However, both strategies require thorough familiarity with the diseases and the tests being used.

Type 1 Autoimmune Pancreatitis and IgG4-Related Sclerosing Cholangitis Is Associated With Extrapancreatic Organ Failure, Malignancy, and Mortality in a Prospective UK Cohort

“…Although serum IgG4 was previously believed to be highly sensitive and specific for AIP ( 27 ), our data show that raised serum IgG4 was present in only 70% of patients at diagnosis. This reinforces data from other studies that serum IgG4 cannot be used in isolation to make a firm diagnosis, or differentiate from other diseases ( 28 - 30 ). We found that pretreatment serum IgG4 level, or its change with treatment, did not predict relapse, but that patients with IgG4-SC were more likely to relapse and had a more complicated course.…”

Endoscopic Ultrasonography‐Guided Fine Needle Aspiration Can Be Used to Rule Out Malignancy in Autoimmune Pancreatitis Patients

“…We investigated whether we could distinguish the 14 pancreatic cancer patients from the 34 autoimmune pancreatitis patients who were not diagnosed by EUS-FNA. For differential diagnosis, we used the capsule-like rim sign 26,[29][30][31][32][33] and narrowing of the main pancreatic duct without extension, 8,30,[34][35][36][37] which are characteristic indicators of autoimmune pancreatitis, as well as serum tumor markers (CEA, CA19-9). We reviewed the capsule-like rim sign by enhanced CT and determined the main pancreatic duct diameter by CT or magnetic resonance imaging (MRI).…”

Autoimmune pancreatitis

“…The pathogenesis of AIP is unknown; however it appears that autoimmune processes play a significant role. Evidence suggestive of the role of immunologic mechanisms include the presence of elevated levels of autoantibodies, characteristic lymphoplasmacytic infiltration on histology, hypergammaglobulinemia and a predictable response to steroids (22,23).…”