Two men (24 and 34 years of age) with a single hypervascular liver tumor were admitted to our hospital. The tumors were diagnosed as hepatocellular adenoma (HCA) by an ultrasound-guided biopsy and classified as inflammatory type by immunohistochemical staining. Considering the risk of malignant transformation, they underwent surgical resection. Although the serum levels of protein induced by vitamin K absence/antagonist-II (PIVKA-II) were slightly elevated, they normalized after the resection. The diagnosis of HCA including malignant transformation is often difficult by image findings alone. Careful immunohistochemical examinations are very useful for the diagnosis and classification of subgroups, including malignant transformation. In addition, we proved that HCA without malignant transformation expresses PIVKA-II.
Keywords: beta-catenin activation; inflammatory hepatocellular adenoma; malignant transformation; protein induced by vitamin K absence/antagonist-II.