Pancreatic lithiasis and intraductal papillary-mucinous neoplasm with special reference to the pathogenesis of lithiasis.

In pancreatic lithiasis in elderly autopsy cases, the stones are small and the pancreatic duct is changed very slightly when viewed by simple X-ray film, pancreatic ductography and gross appearance. Histologically, a slight fibrous increase is seen very locally, but findings consistent with chronic pancreatitis are not found throughout the whole pancreas. However, marked, diffuse and irregular dilatation of the pancreatic duct is frequently found in operative cases with chronic pancreatitis and pancreatic stones. These findings show that the changes seen with aging and with chronic pancreatitis can be distinguished based on the findings of pancreatic ductography. Mucin production in epithelia in intraductal papillary-mucinous neoplasm (IPMN) may not be strongly associated with the pathogenesis of pancreatic lithiasis. Pancreatic lithiasis may be related to squamous cell metaplasia. IPMN and dilatation of the pancreatic duct are closely associated with mucin production. An increase in intraductal pressure of the pancreatic duct may be somewhat related to the mechanism of stone formation. The incidental co-existence of pancreatic epithelia with pancreatic lithiasis in patients with chronic pancreatitis and the development of IPMN may also be possible. IPMN and pancreatic lithiasis may be related through the mechanism(s) of their pathogenesis, their synergism and the pathogenesis of stone formation. The relation between mucinous metaplasia and stone formation is slight and, therefore, there may be only a weak correlation between IPMN and pancreatic stones. This may explain why there are few reports of the co-existence of IPMN and pancreatic stones (Kimura in Kan Tan Sui 58:485-492, 2009).