Case of clear-cell hepatocellular carcinoma that developed in the normal liver of a middle-aged woman.

A 36-year-old woman was admitted to our department for close examination of a liver tumor that was found during a medical checkup. Abdominal US, CT and MRI showed a tumor in segment 7 (S7) of the liver. Although imaging suggested hepatocellular carcinoma, laboratory tests showed no abnormality in liver function, hepatitis virus markers were negative, and tumor markers including protein induced by vitamin K absence or antagonist II (PIVKA-II), alpha-fetoprotein (AFP), carbohydrate antigen 19-9 (CA19-9), and carcinoembryonic antigen (CEA) were all within normal ranges. Upon aspiration biopsy of the liver, the histopathological diagnosis was moderately differentiated hepatocellular carcinoma. Therefore, right hepatectomy was performed. Although a part of the tumor was necrotic, about 60% of the viable part showed a clear-cell variant. Consequently, it was diagnosed as clear-cell hepatocellular carcinoma. It was noted that the background liver tissue was normal. This case is worthy of reporting because development of clear-cell hepatocellular carcinoma in the normal liver of a middle-aged woman is rarely seen.