Immunohistochemical evaluation of canine primary liver carcinomas: distribution of alpha-fetoprotein, carcinoembryonic antigen, keratins and vimentin.

The immunohistochemical expression of the oncofetal proteins alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA), and the intermediate filament proteins keratin and vimentin was analysed in 18 canine liver carcinomas. All the tumours other than hepatocellular carcinomas, with the exception of one poorly differentiated carcinoma, were AFP negative, and only cholangiocarcinomas and mixed (hepatocellular and cholangiocellular) carcinomas were CEA positive. All the histological types of tumours expressed high and low molecular weight keratins, and keratin and vimentin were both expressed in three tumours (one moderately differentiated hepatocellular carcinoma, one mixed carcinoma and one poorly differentiated carcinoma). The findings demonstrate the use of immunohistochemical staining methods for analysing the expression of some tumour markers in routinely processed tissue samples of canine liver carcinomas, and suggest that some of the tumour markers are correlated with histological types of tumour.