Malignant transformation of hepatocellular adenoma over a decade

A 72-year-old man diagnosed with a benign hepatocellular lesion 11 years prior was referred to our hospital for an outgrowth of the tumour in liver segment 7. Extended segmentectomy was performed and the patient's postoperative course was uneventful with no recurrence for 2 years. Histopathological examination confirmed a highly differentiated hepatocellular carcinoma (HCC) coexisting with the hepatocellular adenoma (HCA), and it was suspected to have originated from the HCA. The findings from this case demonstrate that CT can be useful for detecting the transformation of HCA into HCC.