Case ReviewsHepatocellular Adenoma: A Case Report, Current Updates on Subtyping, and Diagnostic PitfallsJung, Geunyoung MD; Liu, Yongjun MD, PhD Author Information From the Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Reprints: Yongjun Liu, MD, PhD, Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, L5/133 CSC, Madison, WI 53792. E-mail: [email protected]. The authors have no funding or conflicts to declare. AJSP: Reviews & Reports 27(6):p 228-233, 11/12 2022. | DOI: 10.1097/PCR.0000000000000527 Buy Metrics Abstract 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. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.