Su1313 Therapeutic Strategy and Predictors in Patients With Type 1 Autoimmune Pancreatitis Associated With Cyst Formation

Abstract

Background and Aims: International Consensus Diagnostic Criteria (ICDC) for autoimmune pancreatitis (AIP) have been proposed to identify type 1 AIP, type 2 AIP, and AIP-not otherwise specified (AIP-NOS). To date, no study on incidence, clinical profiles and outcome in the groups classified according to ICDC has been reported. The aim of this study was to apply these criteria to an Italian series of patients to evaluate the incidence, clinical profiles, and outcome among these subtypes of AIP. Patients and Methods: We re-evaluated and classified 92 patients (16 operated patients and 76 non-operated patients) diagnosed as having AIP by Verona criteria, according to ICDC. Results: Out of 92 patients, 59 patients (64%) were diagnosed as type 1 AIP, 17 (18%) as type 2 AIP, and 15 (16%) as AIP-NOS according to ICDC. A patient showing a spontaneous remission was diagnosed as probable AIP (that fulfilled Verona criteria but not ICDC). Five type 1 AIP patients with ulcerative colitis fulfilled the diagnostic criteria of probable type 2 AIP as well. However, these patients were finally classified into type 1 AIP according to algorithm of ICDC. Type 1 AIP patients compared to type 2 AIP were older (54.5 ± 14.5 vs 34.4 ± 13.9; p ,0.0001) and different in the frequency of male sex (76% vs 47%; p=0.007), jaundice (66% vs 18%; p=0.002) and acute pancreatitis (9% vs 47%; p,0.0001) as initial symptom, elevated serum IgG4 levels (85% vs 7%; p,0.0001), inflammatory bowel disease (8% vs 82%; ,0.0001), and relapse of the disease (34% vs 0%; p=0.002). The clinical and epidemiological parameters in AIPNOS, such as mean age (45.7 ± 14.9), frequency of jaundice (47%) and acute pancreatitis (40%) as initial symptom, and relapse rate (20%), were intermediate between those of type 1 and type 2 AIP. Imaging and response to steroids in AIP-NOS were similar to those in two subtypes of AIP. CONCLUSIONS: Patients diagnosed as type 1 AIP by ICDC have different clinical profiles and outcome from those as type 2 AIP. Although AIP-NOS group seem to be composed of type 1 and type 2 AIP cases without typical clinical and serological features, we cannot exclude an overlap syndrome as a separate entity or as a possible evolution from type 2 AIP to type 1 AIP. ICDC may be unable to diagnose patients with spontaneous remission as having AIP.