Autoimmune pancreatitis in an Asian-dominant American population.

Autoimmune pancreatitis is a rare type of chronic pancreatitis that occurs predominantly in males and was first described in the Asian population. The following study seeks to characterize autoimmune pancreatitis in Hawai'i's Asian-dominant population through a retrospective review of 65 pancreaticoduodenectomy cases performed between 2000 and 2010. Three of the 65 pancreaticoduodenectomies were diagnosed with autoimmune pancreatitis, and 3 additional cases were diagnosed prior to surgery. All six patients were males and presented with obstructive jaundice, 5 with weight loss, and 4 with epigastric pain and elevated serum lipase. All six patients showed elevated serum IgG4. Imaging revealed findings typical of pancreatic malignancy: distal bile duct stricture and pancreatic head mass. However, no nodal involvement and vascular invasion were found. In conclusion, autoimmune pancreatitis should be considered in patients presenting with obstructive jaundice. Elevated serum IgG4, normal serum carbohydrate antigen CA19-9, a benign fine needle aspiration/core biopsy, and a therapeutic response to corticosteroid are typical findings of autoimmune pancreatitis. Serum IgG4 measurement is a useful tool to help differentiate autoimmune pancreatitis from most pancreatic cancers. It is important to consider autoimmune pancreatitis as a differential diagnosis of pancreatic malignancy to avoid unnecessary surgery.