Background: Autoimmune pancreatitis (AIP) is a rare but distinct form of the disease with manifestations both within the pancreas and outside. Autoimmune pancreatitis can present with extrahepatic strictures which can be difficult to distinguish from malignant strictures, including cholangiocarcinoma. Elevated serum IgG4 levels are a feature of autoimmune pancreatitis and histologically the disease is characterised by a significant periductal lymphoplasmacytic infiltration rich in IgG4 positive cells.
Case Report: The following two cases represent the different treatment options available to patients presenting with malignant bile duct strictures thought to be cholangiocarcinoma which eventually proved to be due to autoimmune pancreatitis. Patient 1 is a 62 year old gentleman of South American descent, and patient 2 is a 72 year old Caucasian gentleman.
Conclusions: Pre-operative diagnosis in autoimmune-related bile duct strictures is important as it may negate the need for major complex surgery.

Keywords: autoimmune pancreatitis, Cholangiocarcinoma, pancreatic cancer