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Introduction: Autoimmune pancreatitis (AIP) is a rare, benign inflammatory disease that clinically and radiographically mimics pancreatic adenocarcinoma (PA). When diagnosed, AIP responds well to steroid therapy, but can recur in either the pancreas or biliary system. The inability to accurately distinguish between these two diseases leads many AIP patients to undergo initial pancreaticoduodenectomy. While a 25% disease recurrence rate following steroid therapy in AIP is well established, disease recurrence rates following initial pancreaticoduodenectomy (PD) remains unknown.

Methods: With IRB authorization, 10 patients over a 10 yr period (1999-2009) with pathologically confirmed AIP treated with PD were identified. The study group was matched against two comparison groups of patients with idiopathic chronic pancreatitis (CP) or PA. Clinical presentation, operative variables, and postoperative clinical courses were analyzed. Long-term follow-up, along with quality of life (QOL) data using a validated instrument {Gastrointestinal Symptom Rating Scale (GSRS)} given by structured telephone survey were analyzed. Appropriate statistical tests were applied for nominal and ordinal variables.

Results: The AIP group was 50% male with a mean age of 62 (40-77) yrs. Presenting symptoms were similar between the AIP and PA groups. All groups (AIP, CP, PA) had similar gland morphology on radiographic imaging. Fifty percent of the AIP group had atypia on preoperative FNA biopsy. No AIP pts were diagnosed preoperatively and none had a history of autoimmune diseases. No statistically significant differences were found in operative times, blood loss, perioperative morbidity or mortality (90-day) rates between groups. Mean follow-up for the AIP group was 42 (4.5-83.2) months. Three AIP patients (30%) had disease recurrence: 2 with jaundice and 1 with pancreatitis, at a mean time of 7.7 (1.6-12.1) months postop. All 3 were treated with steroids and 2 had an additional recurrence once the steroids were stopped. Six patients (60%) had no recurrence during follow-up of whom 2 were treated with postoperative ‘prophylactic’ steroids. One patient’s recurrence status remains unknown. Long-term rates of diabetes mellitus, pancreatic exocrine deficiency, and GSRS scores [AIP (N=5); 33 (20-59): CP (N=3); 28 (18-45)] were similar between AIP and CP groups.

Conclusion:Preoperative diagnosis of AIP remains uncommon in our experience in patients with a pancreatic head mass and no history of autoimmune disease. PD in AIP is as safe an operation as it is for CP or PA. AIP recurrence following PD is approximately 30%, with similar long-term postoperative QOL as patients with CP.