Hepatocellular carcinoma arising from adenoma with ARID1A mutation in an adolescent patient with ATM germline mutation

While hepatocellular carcinoma (HCC) is increasingly common in adults, it remains rare in children. Unlike adult HCC, which typically arises from cirrhosis, pediatric cases often occur without underlying liver disease. We report a 14-year-old male with a large hepatic adenoma containing multiple foci of HCC. Genetic testing revealed a germline ATM mutation and a somatic ARID1A mutation. We hypothesize that impaired DNA repair from the ATM mutation facilitated the ARID1A mutation, driving malignant transformation. This case underscores the importance of recognizing malignant potential in hepatic adenomas, utilizing appropriate imaging and pathology, and monitoring for associated cancers in genetically predisposed patients.