[An autopsy case of AFP-producing gastric carcinoma resembling hepatocellular carcinoma on light microscopy]

We experienced an autopsy case of alpha-fetoprotein(AFP)-producing advanced gastric carcinoma with liver metastasis. Microscopically, the tumor was compose by medullary nests of poorly differentiated adenocarcinoma cells. The cells had an exclusively hepatoid pattern characterized by discrete masses, nests, and broad bands, consisting of large eosinophilic epithelial cells and separated by fibrous stroma. Immunohistochemical studies of hepatoid cells yielded a positive reaction for AFP, but negative for CEA. Electron microscopically, tumor cells possess a ductal lumina with abundant microvilli having a central core filaments, and secretory granules in cytoplasma. These findings suggest that the tumor cells differentiated into intestinal direction, irrespective of the appearance of their hepatoid features characterized by light microscopy.