Autoimmune Pancreatitis: A Multiorgan Disease Presenting a Conundrum for Clinicians in the West.

Autoimmune pancreatitis (AIP), a clinical entity originally described in East Asia and more recently recognized in the United States and Europe, poses a diagnostic conundrum for clinicians in the West due to immunoglobulin G4 seronegativity. Although expert panels classify this disease into 2 types, it remains difficult to stratify the disease given that both types share most clinical, biochemical, and imaging characteristics. The classic presentation of AIP can mimic that of pancreatic carcinoma, which increases the urgency of evaluation, diagnosis, and treatment. In this article, we elucidate the differences between the 2 types of AIP, highlight the shortcomings of the current classification system, and propose a more inclusive view of the disorder.