Case Report: Thoracic spinal metastasis without definite intrahepatic recurrence after conversion therapy and hepatectomy for hepatocellular carcinoma.

Introduction: Conversion therapy followed by hepatectomy can achieve intrahepatic control in selected patients with hepatocellular carcinoma (HCC), but occult extrahepatic progression may be missed when surveillance remains centered on the liver. Results: A 61-year-old man with hepatitis B-related multifocal HCC underwent transarterial chemoembolization, lenvatinib, four documented preoperative cycles of tislelizumab, and subsequent hepatectomy. Pathology showed treatment-related response, negative margins, and no microvascular invasion. During scheduled surveillance, alpha-fetoprotein and des-gamma-carboxy prothrombin increased progressively despite no definite intrahepatic recurrence on available liver imaging. PET/CT later revealed a destructive T2 vertebral lesion. After local radiotherapy, no dedicated spine MRI or multidisciplinary spinal assessment was performed before neurological deterioration. At emergency admission, lower-limb strength was initially preserved on the right and partially reduced on the left, followed by rapid bilateral paralysis. Contrast-enhanced thoracic MRI showed multilevel metastases with a dominant T8 lesion causing epidural spinal cord compression and pathological fracture. Fixation and decompression relieved radiological compression, but severe motor and autonomic dysfunction persisted. Discussion: The clinical value of this case lies in a surveillance gap rather than rarity alone. Persistent AFP/DCP elevation with negative liver imaging should prompt systemic restaging for occult extrahepatic disease. Once a destructive vertebral lesion is detected, early spine MRI and multidisciplinary assessment of stability and epidural compression are warranted before irreversible neurological injury develops.