A 54-year-old African American male presents to the ER with nausea, vomiting, weight loss, and upper abdominal pain radiating to the back. Physical exam demonstrates a well-developed, nonobese male...

A 54-year-old African American male presents to the ER with nausea, vomiting, weight loss, and upper abdominal pain radiating to the back. Physical exam demonstrates a well-developed, nonobese male with moderate abdominal tenderness; you note a mild scleral icterus (yellowing of the eyes). A CT demonstrates a large pancreatic mass, and blood studies are remarkable for elevation of nonalbumin protein, which is determined to be IgG4 on additional testing. What is the most likely etiology of his pancreatitis?

A. Autoimmune

B. Gallstones

C. Malignancy

D. Alcohol abuse