Abstract
Hepatocellular adenoma (HA) is a benign tumor and extremely rare. We report an 80-year-old man with hepatocellular carcinoma (HCC) mimicking a hepatocellular adenoma. The patient was admitted to the hospital because of a hepatic tumor detected by abdominal ultrasonography. HBs antigen and HCV antibody were negative and liver function test and the serum level of alpha-fetoprotein were within normal ranges. Abdominal ultrasonography showed a hyperechoic, well-defined nodule 4cm in diameter in the segment 2 of the liver. Abdominal magnetic resonance imaging scan showed low signal intensity on T1- and high signal intensity on T2-weighted images. Because a possibility of HCC could not be ruled out from these imaging findings which suggested benign hepatic tumor, lateral segmentectomy was performed. Grossly the tumor had a capsule and histopathological examination showed thin-trabecular pattern. There were no portal tracts. It was difficult to diagnose the tumor as HCC because of the morphology which was similar to HA. However, infiltration of the tumor into the peritumoral capsule was seen in the restricted area. The tumor was thus diagnosed as well to moderately differentiated HCC. Histologically, well differentiated HCC may be difficult to distinguish from HA.
