[Mediastinal Metastasis of Mixed Hepatocellular Carcinoma Requiring Differential Diagnosis from Thymic Carcinoma].

A 71-year-old man underwent S8 segmentectomy for mixed hepatocellular carcinoma. The disease recurred three months postoperatively, prompting a right lobectomy of the remaining liver. Prior to the liver recurrence, three nodules were identified in the anterior mediastinum. At the patient's request, dendritic cell vaccine therapy was administered following the recurrence. Two of the nodules decreased in size, while one nodule increased. Consequently, the patient was referred to our department for further evaluation. Differentiating between thymic carcinoma and mediastinal metastasis of hepatocellular carcinoma was challenging, leading to the decision to perform resection under the assumption of thymic carcinoma. A bilateral simultaneous thoracoscopic total thymectomy was conducted. Pathological examination revealed a poorly differentiated carcinoma with sarcomatoid morphology. Histologically similar lesions were observed in the preexisting liver tumor and lymph nodes, indicating metastasis from the mixed liver cancer. As of four and three months post-surgery, no recurrence has been noted. The patient will continue to receive immunotherapy and will be monitored closely. This case represents an extremely rare instance of mediastinal metastasis from mixed hepatocellular carcinoma. The prognosis for mediastinal metastasis of liver cancer is generally poor, underscoring the importance of vigilant follow-up.