Pancreatic ductal mucinous hyperplasia: distribution within the pancreas, and effect of variation in ampullary and pancreatic duct anatomy.

The prevalence and amount (hyperplasia score) of ductal mucinous hyperplasia (DMH) were estimated in 12 predetermined areas taken from 102 pancreases obtained at necropsy from patients dying of non-pancreatic diseases. The mean prevalence of DMH was 18% (213/1206) per section and 63% (63/102) per pancreas. Different areas of the pancreas could be stratified by amount of DMH into 'high' (hyperplasia score greater than 0.09), 'intermediate' (0.06-0.09), and 'low' (less than 0.06). There was no significant difference in either prevalence or amount of DMH with variation in ampullary or pancreatic ductal anatomy. There was significantly (p less than 0.05) less DMH adjacent to the accessory papilla when it was patent, compared with when it was not patent and the accessory duct communicated with the main pancreatic duct. The findings suggest that DMH is a proliferative response to exogenous agents which injure the pancreas, and that some areas of the pancreas are more vulnerable than others to this damage. There was no evidence that this injury was associated either with reflux, or with any particular variation in pancreatic duct anatomy. The association between DMH and occlusion of the accessory papilla may explain the susceptibility of pancreas divisum to pancreatitis.