Autoimmune Pancreatitis: More Than Just a Pancreatic Disease?A Contemporary Review of Its Pathology

Abstract

Abstract Context.—Autoimmune pancreatitis (AIP) is a chronic inflammatory condition of the pancreas constituting one quarter of Whipple resections performed for benign conditions in North America. Objective.—We review the clinical, radiologic, and characteristic histopathologic patterns of this disease and discuss the extrapancreatic manifestations of AIP. Design.—We searched the literature using MEDLINE and OVID, related conference abstracts, and bibliographies of selected studies. Results.—Autoimmune pancreatitis predominantly affects elderly individuals, frequently presenting as obstructive jaundice and occasionally in association with other autoimmune diseases. The histology is characterized by a collar of periductal inflammation, obliterative phlebitis, and the absence of stigmata of alcoholic pancreatitis. A prepancreatectomy diagnosis can be rendered using a combination of clinical findings, radiologic features, elevated immunoglobulin G4 levels, endoscopic ultrasound-guided fine-needle aspiration biopsy, and response to steroids. The disease can involve the bile ducts (sclerosing cholangitis), gallbladder (lymphoplasmacytic sclerosing cholecystitis), and kidney (interstitial nephritis) and can form inflammatory masses in the lungs. Conclusions.—Despite significant evolution in our understanding of AIP, a prepancreatectomy diagnosis remains a challenge in the North American and European population.