Intracranial metastasis of hepatocellular carcinoma with SMARCA4/BRG1 deficiency: A case report of a young patient easily misdiagnosed as atypical teratoid/rhabdoid tumor.

Hepatocellular carcinoma (HCC) is the most frequent histological subtype of primary liver cancer, accounting for 80 - 90% of all cases.SMARCA4/BRG1 (Brahma-related gene 1) has been reported as a tumor-promoting factor in HCC, with high expression being associated with advanced stage and poor prognosis. At present, SMARCA4/BRG1-deficient HCC is an extremely rare subtype, accounting for less than 1% of cases, and intracranial metastasis arising from this subtype has been scarcely documented. We report a rare case of a young patient presenting with intracerebral hemorrhage as the initial manifestation, for whom the initial pathological diagnosis was atypical teratoid/rhabdoid tumor, but eventually diagnosed with brain metastasis from SMARCA4/BRG1 deficient HCC. This case reminds us that in adult patients presenting with intracranial tumors exhibiting SMARCA4/BRG1 deficiency, a high index of suspicion for brain metastasis from HCC is warranted. SMARCA4/BRG1 deficiency typically endows tumors with increased invasiveness and suggests that this deficient state may reshape metastatic tropism, thereby conferring the ability to traverse the blood-brain barrier. These observations may provide a foundation for future studies investigating the molecular mechanisms underlying metastasis in this subset of tumors.