Primary hepatocellular carcinoma and hepatoid adenocarcinoma of the stomach with liver metastasis: an unusual association.

Alpha-fetoprotein (AFP)-producing hepatoid adenocarcinoma of the stomach is a rare and recently discovered entity. We report an unusual combination of hepatocellular carcinoma and hepatoid adenocarcinoma of the stomach with multiple liver metastases. The patient, a 62-year-old Japanese man, was clinically diagnosed as having hepatocellular carcinoma because of the presence of liver tumors, a markedly elevated serum AFP level, and a positive hepatitis C virus (HCV) antibody titer. Autopsy revealed multiple tumors in the liver; one was a primary hepatocellular carcinoma without metastasis, and the others were metastases from latent hepatoid adenocarcinoma of the stomach. In the hepatocellular carcinoma, bile production was observed although the tumor was immunohistochemically negative for AFP. On the other hand, both the primary gastric and metastatic liver hepatoid adenocarcinomas were positive for AFP. Therefore, hepatoid adenocarcinoma of the stomach was responsible for the excessive production of AFP and was the cause of death.