Morphological evaluation of metastatic cholangiocarcinoma in a dog

Abstract

Cholangiocellular carcinomas are aggressive, malignant neoplasms of biliary epithelium usually arising from intrahepatic bile ducts. The aim of this study was to describe the immunohistochemical characteristics of metastatic ductular/papillary cholangiocarcinoma in a common breed dog. A 16-year old common breed dog was submitted for necropsy with an anamnesis of apathy, vomiting, anorexia and intermittent neurological symptoms. After complete necropsy, samples were taken and processed using paraffin technique. The sections were stained with Hematoxylin-eosin, Masson’s trichrome, and PAS methods. Immunohistochemical examination was also performed using alpha smooth muscle actin, multicytokeratin AE1/AE3, cytokeratin 7, cytokeratin 19 and vimentin antibodies. At necropsy multiple masses in the liver parenchyma, and several metastases in the lungs, pancreas, intestinal serosa, omentum and on the surface of the diaphragm muscle were observed. Histologically the tumor consisted of pleomorphic epithelial cells, arranged in ductules, presenting intraluminal papillary growth pattern and marked fibroplasia. Vascular invasion, intra and extrahepatic metastases were also present. The tumoral cells were AE1/AE3, cytokeratin 7 and cytokeratin 19 positive, alfa smooth muscle actin and vimentin negative. Immunohistochemical exam proved to be useful in differentiating cholangiocellular carcinoma from hepatocellular carcinoma and several extrahepatic metastatic carcinomas.