Hepatocellular Adenoma: A Case Report, Current Updates on Subtyping, and Diagnostic Pitfalls

Hepatocellular adenoma (HCA) is a benign liver neoplasm that typically arises in the noncirrhotic liver. Based on molecular findings, HCA can be subclassified into the following subtypes: hepatocyte nuclear factor 1α–inactivated HCA, inflammatory HCA, β-catenin–activated HCA, sonic hedgehog-activated HCA, and unclassified HCA. Mixed β-catenin–activated inflammatory HCA may rarely occur. We report a case of HCA that was initially diagnosed as inflammatory HCA on a biopsy but finally was confirmed to be β-catenin–activated inflammatory HCA on the resection specimen. Most recent updates on molecular classification, key histologic features of each subtype, and common diagnostic pitfalls are discussed.