S5595 An Unusual Case of Isolated Bony Metastatic Recurrence of Hepatocellular Carcinoma Six Years After Liver Transplantation

Introduction: Liver transplant (LT) remains a definitive therapy for hepatocellular carcinoma (HCC) with evolving selection criteria enabling a curative intent in a broader patient population. Post-LT HCC recurrence remains high with 8%-20% of cases occurring within 2 years. Late recurrence (>5 years) is rare. Current guidelines lack standardized post-LT surveillance protocols. We present a case of isolated bony recurrence HCC occurring 6 years post-LT. Case Description/Methods: A 63-year-old man with hepatitis C related cirrhosis and HCC underwent orthotopic liver transplantation in 2017. Explant tissue pathology was consistent with poorly differentiated HCC (tumors 1.2 cm and 1.1 cm) without lymphovascularinvasion or extrahepatic disease. Post LT, he was placed on immunosuppression with routine monitoring of alpha-fetoprotein (AFP) levels and computed tomography (CT) imaging, which showed no evidence of disease recurrence. In January 2023, after being declared cured, he presented with neck pain and was found to have a pathologic C4 fracture. Biopsy confirmed metastatic HCC, and imaging showed no other metastatic lesions. He subsequently underwent embolization, resection, and radiation. He was initiated on Lenvatinib and AFP was 1,614 in April which normalized by July and further imaging did not show active disease. Despite a short respite, AFP levels increased to 1,693 in May 2024 and magnetic resonance imagiconfirmed recurrence of HCC at C3-C4. He was treated with radiation and ramucirumab in September. The following month, he presented with acute weakness and cord compression from a pathologic T8 fracture and underwent T7-T9 decompressive laminectomy, regaining partial function before ultimately transitioning to hospice due to repeated readmissions. Discussion: Bone metastases from primary HCC are rare, reported in 5%-15% of cases, but carry high morbidity and mortality with amedian survival of 7 to 19 months. Despite adherence to Milan criteria for selection of transplant candidates, tumor recurrence remains prevalent. Risk is influenced by microvascular invasion, elevated AFP, tumor staging, and use of immunosuppression. Lower AFP levels before LT have been shown to have superior 5-year recurrence-free survival. This unique case of isolated bony metastatic HCC 6 years post liver transplant challenges conventional understanding of HCC recurrence timelines and patterns. This calls for renewed attention to long term surveillance strategies for transplant recipients, particularly those with high-risk tumor biology despite initial favorable pathology.