The patient was a 72-year-old man who had a history of hepatic cyst, which had, however, not been followed up. It was noted that he had internal hemorrhage in the hepatic cyst as well as a contrast-enhanced tumorous lesion in the cystic wall. Further detailed examination could not rule out hepatic cystadenocarcinoma or cystadenoma, so a right hepatic lobectomy was performed. The lesion was histopathologically diagnosed as non-malignant cyst with angiogenesis simulating cavernous hemangioma and intra-cystic hemorrhage. Although this disease is difficult to diagnose, its diagnosis is not impossible as long as the disease is kept in mind.