Pathogenesis of duct hyperplasia in the pancreas.

Causative factors in duct hyperplasia were histologically examined by using 1,388 autopsied pancreases. Duct hyperplasia was frequent in pancreases having primary carcinoma and in those having necrotizing pancreatitis, but it was not frequent in those with interstitial pancreatitis, ductal pancreatitis, and other disorders. Duct hyperplasia was almost always found in ducts which connected with small ducts having a feature of adenomatous hyperplasia or ductular aggregation in foci of intralobular fibrosis. A histologic examination revealed that these fibrous foci are likely the vestiges of fat necrosis, mostly of a subclinical one.