Histologic findings were evaluated in a pancreatic polypeptide-rich area, named the ventral pancreas, because ampullary carcinomas are anatomically involved in the outflow of the pancreatic juice from Wirsung's duct or the main pancreatic duct but not from Santorini's duct or the accessory pancreatic duct. Histologic changes in fibrosis were divided into 3 categories as follows: mild change showing rather diffuse distribution of mild interlobular fibrosis, seldom accompanied by acinar atrophy; moderate change revealing moderate interlobular up to moderate intralobular fibrosis with acinar atrophy; and marked change showing marked interlobular up to marked intralobular fibrosis with acinar atrophy.