Evaluation and management of autoimmune pancreatitis: experience at a large US center.

Objectives: Autoimmune pancreatitis (AIP) is increasingly recognized as a form of chronic pancreatitis. Systematic evaluation and management of AIP in the United States is reported only from one center. Our aim was to review the evaluation and management of AIP at a large tertiary center.

Methods: We retrospectively reviewed information on demographics, clinical presentation, laboratory and imaging findings, extrapancreatic involvement, treatment response, and recurrence in 26 patients with AIP treated at the University of Pittsburgh Medical Center from 1998 to 2007.

Results: The median age at presentation was 62.5 years (range: 23-86), 65% were men, and 88% were Caucasians. The most common presentation included new-onset mild abdominal pain (65%), jaundice (62%), and weight loss (42%). Pancreatic mass, enlargement, or prominence on imaging was present in 85% of the patients. Serum IgG4 (immunoglobulin-4) was elevated (>140 mg/dl) in 44% (8/18) at presentation. The most common extrapancreatic finding was extrapancreatic/intrahepatic biliary strictures (35%). Peri-pancreatic vascular complications were noted in 23% of the patients. Six patients underwent partial or complete pancreatectomy. Partial or complete response was observed for initial steroid treatment in 19 patients and for methotrexate in 1 patient. Recurrences were common, especially in patients with extrapancreatic manifestations, and usually responded to a combination of steroids and azathioprine. Any one of the commonly used diagnostic criteria (Mayo Clinic's HISORt criteria, the Japanese Pancreas Society criteria, Korean diagnostic criteria) was fulfilled in 85% of cases.

Conclusions: In this second major US series, we confirm several findings previously reported in AIP. Our study highlights the presence of vascular complications in a subset of patients with AIP. The current diagnostic criteria may not identify all AIP patients.