Is Type 2 Autoimmune Pancreatitis Rare in Asia? Prevalence, Clinical Outcomes, Radiological Features and Response to Steroids of Type 2 Autoimmune Pancreatitis in Korea

Abstract

Backgrounds: Recently, two distinct histological patterns of autoimmune pancreatitis (AIP), type 1 AIP and type 2 AIP, have been recognized. Type 2 AIP has been reported mainly in western countries and is known to be rare in Asia. The aim of this study was to compare the prevalence, clinical profiles, radiological findings and response to steroids of type 1 and type 2 AIP in Korea. Methods: From 120 patients diagnosed with AIP between January 2003 and March 2010, 52 patients with histologically confirmed type 1 (n=37) or type 2 (n=15) AIP were included. We reviewed the prospectively collected data on these patients. Results: The type 2 AIP patients' median age (34 years) was significantly lower than that of the type 1 AIP patients (61 years) (p 1,800 mg/dL, 54.1% in type 1 AIP vs. 0% in type 2, p 135 mg/dL, 70.3% in type 1 AIP vs. 0% in type 2 AIP, p<0.05). Ulcerative colitis was associated with only type 2 AIP (33.3%), but type 2 AIP patients had no other extrapancreatic involvements. Steroid therapy was performed on 41 patients (27 in type 1 AIP and 14 in type 2 AIP), and all of whom improved clinically and radiologically in response to it. During the follow-up period (median 714 days in type 1 AIP vs. 489 days in type 2 AIP, p=0.166), 32.4% of type 1 AIP patients experienced a relapse, but none of the type 2 AIP patients did (p<0.05). Conclusion: It is suggested that type 2 AIP might not be rare in Korea unlike the results of previous studies. Type 1 and type 2 AIP patients had similar radiological findings and response to steroids, but they showed distinct initial clinical presentations, serology and relapse rate.