Primary hepatocellular carcinoma with hepatitis B virus-DNA integration in a 4-year-old boy

The autopsy findings in a case of hepatocellular carcinoma with hepatitis B virus (HBV)-DNA integration in a Japanese boy, 4 years and 10 month of age, are reported. The boy was an HBV carrier born in a typical familial cluster of HBV infection in Japan. He had been asymptomatic until the sudden manifestation of the liver tumor. Histopathologic examination revealed a well-differentiated, adult-type hepatocellular carcinoma without hepatic cirrhosis. HBV-DNA sequences were detected in the tumor cell DNA by the Southern blot hybridization method. This is the youngest patient with hepatocellular carcinoma with HBV-DNA integration reported to date, suggesting that HBV may manifest its oncogenic properties after a shorter incubation period than generally believed.