Prevalence, Diagnosis, and Profile of Autoimmune Pancreatitis Presenting with Features of Acute or Chronic Pancreatitis

BACKGROUND & AIMS: Little is known about how many patients with features of acute pancrearitis (AP) or chronic pancreatitis (CP) have autoimmune pancreatitis (Al P); most information comes from case reports. We explored the clinical profiles and relationship between these diseases. METHODS: We evaluated 178 patients presenting to our Pancreas Clinic between January 2005 and June 2006 for evaluation of the etiology of their suspected pancreatitis; AIP was diagnosed when patients met HISORt (Histology, Imaging features, Serology. Other organ involvement and Response to steroid treatment) criteria. In a separate cohort of patients with AIP from our database, we identified patients who presented with features of AP of abdominal pain, increased pancreatic enzymes, pancreatic inflammation determined by imaging analyses) or CP I of pancreatic calcification, irregular main pancreatic duct dilation, or marked atrophy) and determined their clinical profile. RESULTS: Only 7/178 (3.9%) patients evaluated for etiology of suspected pancreatitis had AIR Among 63 AIP patients in our database, 22 (34.9%) had features of AP (n = 15) or CP (n = 7) at presentation (average age 53.4 +/- 19.0 years, all males). Patients with AIP and pancreatiris were characterized by presence of obstructive jaundice (59.1%), increased levels of liver enzymes (81.8%), increased levels of serum immunoglobulin G4 (80.9%), and other organ involvement (69.1%). All 19 patients presenting with pancreatitis who were treated with steroids responded to treatment. CONCLUSIONS: While AIP is an uncommon etiology for acute or chronic pancreatitis, >33% of AIP have features of acute or chronic pancreatitis at presentation.