Abstract
This report presents the case of a 70-year-old female patient with hepatocellular carcinoma (HCC) who was hospitalized for fever of unknown origin. We confirmed the diagnosis of HCC with lymphadenopathy through needle biopsy. The patient experienced hypertension and malaise after therapy with tislelizumab plus lenvatinib. Additionally, there was a persistent decrease in T3 and T4 levels accompanied by elevated TSH levels. During treatment, tumor regression and notable shrinkage of enlarged lymph nodes met the criteria for surgical intervention. However, since the patient's family declined surgery, the tumor subsequently progressed, resulting in clinical deterioration. This case highlights the uncommon occurrence of hypothyroidism after targeted immunotherapy in HCC patients and emphasizes the critical role of monitoring thyroid function in prognosis assessment. Conclusion: Hypothyroidism following combination therapy with tislelizumab and lenvatinib in HCC may indicate a favorable therapeutic response. Early surgical intervention is recommended once tumor shrinkage and symptom improvement occur.