The patient was a 79-year-old male. In December 2002, US findings suggested hepatocellular carcinoma, and he was admitted. Liver biopsy led to a diagnosis of well-differentiated hepatocellular carcinoma. Radio frequency ablation (RFA) was performed. Then, regional relapse was detected, and treatment was repeated. However, follow-up with periodic imaging was continued based on the patient's wishes. RFA was completed in December 2005, and TAI in February 2006. In December 2007, abdominal swelling occurred. CT revealed pleural effusion/ascites and nodular tumor in the adipose tissue of the parietal peritoneum and mesentery around the liver. The patient died due to rapid deterioration. Autopsy revealed a tumor involving the liver surface to the peritoneum, suggesting cancerous peritonitis. Histopathologically, liver cancer showed sarcoma-like changes, directly infiltrating the liver surface to the peritoneum. Hepatocellular carcinoma with sarcoma-like changes and peritoneal dissemination is rare. In the present case, it was possible to compare imaging changes with autopsy findings. We report this patient and review the literature.