A 49-year-old Japanese woman with polycystic liver disease (PLD) was admitted for right hypochondrial pain. CT showed a huge enhancing mass in the liver. She tested negative for other liver diseases, such as hepatitis B and C and alcoholic liver disease. After the patient expired due to hepatic failure, an autopsy revealed poorly differentiated hepatocellular carcinoma (HCC) surrounded by multiple hepatic cysts. The small amount of residual hepatic parenchyma showed nonalcoholic fatty liver disease (NAFLD) with severe steatosis. Severe emaciation was also apparent. This case suggests that malnutrition in patients with symptomatic PLD may contribute to the development of HCC via NAFLD.