Histopathologic and immunohistochemical studies on alcoholic pancreatitis and chronic obstructive pancreatitis: special emphasis on ductal obstruction and genesis of pancreatitis.

We compared alcoholic pancreatitis (AP), which is thought to be caused by protein plugs, and chronic obstructive pancreatitis (COP), distal to carcinoma, both histopathologically and immunohistochemically. Eighteen cases of AP showed marked and irregularly distributed interlobular fibrosis. The exocrine parenchyma and its immunoreactivity against anti-amylase were rather well preserved, except in the advanced stages of the disease. Protein plugs and pancreatic stones were found. Fifteen cases of COP showed a uniform distribution of inter- and intralobular fibrosis, marked destruction of the exocrine parenchyma, and loss of amylase concentration. Neither protein plugs nor pancreatic stones were found. Anti-collagen immunoreactivity was found in both types of pancreatitis. Although obstruction of the main or small pancreatic ducts is considered to be the principal factor in the genesis of both AP and COP, the histological features of the two diseases are quite distinct from one another. Therefore, duct obstruction caused by protein plugs appears not to be the main factor in the genesis of alcoholic pancreatitis.