Two forms of hereditary chronic pancreatitis.

We report 11 families of hereditary pancreatitis characterized by the presence of calculi in pancreatic ducts. These were classified as (1) calcic lithiasis (one family with five cases), in which the calculi are composed of >95% calcium salts; and (2) protein lithiasis in 10 families, in which the calculi are composed of degraded amorphous residues of lithostathine, the pancreatic secretory protein that inhibits calcium salt crystallization. In both forms, transmission appears to be dominant. The average age at clinical onset of symptoms is 15 years. The clinical progression seems to be less severe than in alcoholic chronic pancreatitis (alcoholic calcic lithiasis). This report shows for the first time that hereditary chronic pancreatitis is a group of at least two diseases having a similar clinical picture and pathological features but different chemical compositions of calculi. This leads us to propose a revised Marseille-Rome classification.