The pathology of chronic pancreatitis.

We describe the current concepts of the pathology of alcoholic and obstructive chronic pancreatitis (CP). These 2 types of CP possess distinct pathological features. Alcoholic CP is associated with a lobular distribution of the lesions, with both obstruction (from protein plugs) and dilatation of the canalicular and intercalated ducts. In alcoholics, the concentration of protein in the pancreatic juice is increased, making the precipitation of proteinaceous plugs likely. Obstructive CP, on the other hand, is rarely associated with intraductal precipitates; the small ducts are often normal in appearance, but exocrine damage is much more widespread. The complications of CP are varied. Jaundice, while usually transient, may occasionally be permanent. This results from the compression of the distal common bile duct by fibrotic changes in the pancreatic head. Transient or permanent obstruction of the duodenum and/or colon may also occur. Nearby vessels may be involved, leading to thrombosis and/or hemorrhage from veins or arteries. Electron microscopic changes recently described in the pancreatic nerves may play a role in the etiopathogenesis of the severe pain so common in patients with CP.