Hepatocyte paraffin 1: a monoclonal antibody that reacts with hepatocytes and can be used for differential diagnosis of hepatic tumors

Hepatocyte paraffin 1 is a monoclonal antibody that has been developed specifically to react with hepatocytes in routine formalin-fixed and paraffin-embedded surgical pathology tissues. It results in a distinct, granular cytoplasmic staining of hepatocytes but fails to react with bile ducts and nonparenchymal liver cells. The antibody decorates a majority of hepatocellular carcinomas, including fibrolamellar variants. It fails to react with a wide variety of other adult malignancies, with the exception of focal staining in a few gastrointestinal malignancies, including a subpopulation of gastric carcinomas.