The clinical presentation for this is all wrong. Most patients with acute pancreatitis will present with abdominal pain, nausea, and vomiting. There was none of that in the history.
The changes in the pancreas are from inflammatory damage, the most common chronic cause of which is alcohol consumption - however, there are no liver signs. He might have had acute pancreatitis in the past, though; gallstones can cause the reflux of bile up the pancreatic duct, which can lead to autodigestion and inflammation. You know the patient's had a cholecystectomy in the past, so that's a definite possibility.