Comparison of clinical findings between histologically confirmed type 1 and type 2 autoimmune pancreatitis.

BACKGROUND AND AIM: Type 2 autoimmune pancreatitis (AIP) has been reported mainly in Western countries and is thought to be very rare in Asia. The aim of this study was to compare the prevalence, clinical profiles, detailed radiological findings, and steroid responsiveness between type 1 and type 2 AIP in Korea.

METHODS: From 120 patients diagnosed with AIP between January 2003 and August 2010, 52 patients with histologically confirmed type 1 (n = 37) or type 2 (n = 15) AIP were included.

RESULTS: The median age of patients with type 2 AIP was significantly lower than that of patients with type 1 AIP (61 vs 34 years, P < 0.05). At initial presentation, severe abdominal pain and presentation with acute pancreatitis were more frequent in patients with type 2 AIP (P < 0.05). On computed tomography scan, the extent of pancreatic enlargement and the frequency of low-density mass did not differ significantly between the two groups. Detailed pancreatographic findings on endoscopic retrograde cholangiopancreatography/magnetic resonance cholangiopancreatography were not significantly different between the two groups. All patients with steroids therapy improved clinically and radiologically in response (25/25 in type 1 AIP and 14/14 in type 2 AIP). During the follow-up period, none of the patients with type 2 AIP experienced relapse.

CONCLUSIONS: Type 2 AIP in all histologically confirmed AIP cases in Korea may not be as rare as originally thought, with an estimated prevalence rate of 28.8% (15/52). The detailed radiological findings of type 1 and type 2 AIP were not significantly different, and both subtypes responded well to steroids.