Adenocarcinoma of the hepatopancreatic ampulla in a domestic cat.

A 13-year-old spayed female Siamese cat was submitted for necropsy following unsuccessful treatment for obstructive jaundice. Histopathologic examination revealed an adenocarcinoma of the hepatopancreatic ampulla. The carcinoma obstructed the pancreatic and common bile ducts entering the ampulla, resulting in severe diffuse acinar degeneration, atrophy and fibrosis of the pancreas, and dilatation of the bile ducts, biliary fibrosis, and ductule proliferation in the liver. In humans, carcinoma of the ampulla of Vater, the hepatopancreatic ampulla, is considered an uncommon malignancy.