Albumin gene expression in adenocarcinomas with hepatoid differentiation

Two cases of hepatoid adenocarcinomas were studied with an in situ hybridiz ation technique (ISH) using a RNA probe for human albumin mRNA. In case 1 t he urinary bladder of a 67-year-old woman was affected; in case 2 the tumou r was located in the gastric antrum of an 80-year-old woman. In neither cas e had alpha fetoprotein (AFP) been determined preoperatively. Histologicall y these cases showed adenocarcinomatous features intermingled with hepatoid areas. These latter areas were characterized by cords of polygonal cells, each with an oval nucleus and prominent nucleoli, separated by a fine netwo rk of sinusoids. In the hepatoid areas the immunohistochemical profile was similar to that observed in hepatocellular carcinomas, in that the tumour c ells were positive with AFP, alpha-1-antitrypsin (A1AAT) and albumin antise ra and there was a canalicular type of reactivity with polyclonal anti-CEA (pCEA) antibody. ISH revealed albumin mRNA in virtually all hepatoid cells in case 1, and in about 50% of those in case 2. In addition, in case 2 occa sional cells in the adenocarcinomatous areas showed albumin transcripts of ISH. Our findings confirm that ISH for albumin mRNA probe is a valuable met hod of establishing hepatocellular differentiation, and that hepatoid adeno carcinomas are tumours with true extrahepatic hepatocellular differentiatio n.