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World J Gastrointest Endosc. Jan 16, 2010; 2(1): 20-24
Published online Jan 16, 2010. doi: 10.4253/wjge.v2.i1.20
Endoscopic approach for diagnosing autoimmune pancreatitis
Terumi Kamisawa, Hajime Anjiki, Kensuku Takuma, Naoto Egawa, Takao Itoi, Fumihide Itokawa
Terumi Kamisawa, Hajime Anjiki, Kensuku Takuma, Naoto Egawa, Department of Internal Medicine, Tokyo Metropolitan Komagome Hospital, Tokyo 113-8677, Japan
Takao Itoi, Fumihide Itokawa, Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo 113-8677, Japan
Author contributions: Kamisawa T wrote the paper; Kamisawa T, Anjiki H, Takuma K, Egawa N, Itoi T, and Itokawa F collected data.
Correspondence to: Terumi Kamisawa, MD, PhD, Director, Department of Internal Medicine, Tokyo Metropolitan Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan.
Telephone: +81-3-38232101   Fax: +81-3-38241552
Received: February 24, 2009
Revised: August 26, 2009
Accepted: September 2, 2009
Published online: January 16, 2010

It is of utmost importance to differentiate autoimmune pancreatitis (AIP) from pancreatic cancer (PC). Segmental AIP cases are sometimes difficult to differentiate from PC. On endoscopic retrograde cholangiopancreatography, long or skipped irregular narrowing of the main pancreatic duct (MPD), less upstream dilatation of the distal MPD, side branches derived from the narrowed portion of the MPD, absence of obstruction of the MPD, and stenosis of the intrahepatic bile duct suggest AIP rather than PC. Abundant infiltration of IgG4-positive plasma cells is frequently and rather specifically detected in the major duodenal papilla of AIP patients. IgG4-immunostaining of biopsy specimens obtained from the major duodenal papilla is useful for supporting a diagnosis of AIP with pancreatic head involvement. On endoscopic ultrasonography (EUS), hyperechoic spots in the hypoechoic mass and the duct-penetrating sign suggest AIP rather than PC. EUS and intraductal ultrasonography sometimes show wall thickening of the common bile duct even in the segment in which abnormalities are not clearly observed with cholangiography in AIP patients. EUS-guided fine needle aspiration, especially EUS-guided Tru-Cut biopsy, is useful to diagnose AIP, as well as to exclude PC.

Keywords: Autoimmune pancreatitis, Pancreatic cancer, Endoscopic retrograde cholangiopancreatography, Endoscopic ultrasonography-Fine needle aspiration, IgG4