Supplementary Material for: Contrast-enhanced ultrasound of metastatic clear cell sarcoma of the liver: a case report and review of the literature

Introduction: Clear cell sarcoma (CCS) is a rare malignant soft tissue tumor derived from neural crest cells, and it exhibits a high tendency for recurrence and metastasis. Distant metastasis significantly affects the prognosis. The incidence of liver metastasis from CCS is very low, and related contrast-enhanced ultrasound imaging reports are scarce.
Case report: We herein report a case involving a 23-year-old Tibetan man who was admitted to the hospital with swelling, pain, and limited movement of the right knee joint. Imaging revealed a tumor in the right knee, and preoperative examinations detected multiple liver lesions. Contrast-enhanced ultrasound showed high enhancement with a thick rim and uneven iso-enhancement in the center during the arterial phase, slow washout of the rim in the portal to delayed phases, and uneven low enhancement centrally. Based on these imaging findings and the patient’s history, hepatic tuberculosis was considered, although a tumor could not be ruled out. Laboratory tests—including routine blood, liver function were normal, and most tumor markers were normal except neuron-specific enolase. The patient underwent surgical resection of the knee tumor, and pathological diagnosis confirmed CCS. The liver lesions were further evaluated with contrast-enhanced computed tomography and enhanced magnetic resonance imaging, but a definitive diagnosis remained elusive. Ultimately, ultrasound-guided needle biopsy confirmed liver metastasis from CCS.
Conclusion: In conclusion, Contrast-enhanced ultrasound has a good effect on the diagnosis of liver metastases. Combining with the relevant medical history of the patient or identifying the primary lesion can increase diagnostic confidence.

引言：透明细胞肉瘤（Clear cell sarcoma, CCS）是一种起源于神经嵴细胞的罕见恶性软组织肿瘤，具有较高的复发与转移倾向，远处转移可显著影响患者预后。该肿瘤发生肝转移的概率极低，相关增强超声（contrast-enhanced ultrasound）报道较为稀少。
病例报告：本文报告1例23岁藏族男性患者，因右膝关节肿胀、疼痛伴活动受限入院。影像学检查发现右膝关节存在肿物，术前检查检出肝脏多发病变。增强超声检查显示，病灶动脉期呈厚壁高强化，中央为不均匀等强化；门脉期至延迟期病灶边缘洗脱缓慢，中央呈不均匀低强化。结合上述影像学表现与患者病史，临床考虑为肝结核，但无法排除肿瘤性病变。实验室检查结果显示：血常规、肝功能均正常，除神经元特异性烯醇化酶（neuron-specific enolase）外，其余多数肿瘤标志物水平处于正常范围。患者接受膝关节肿物切除术，术后病理诊断证实为透明细胞肉瘤。后续通过增强计算机断层扫描（contrast-enhanced computed tomography）与增强磁共振成像（enhanced magnetic resonance imaging）对肝脏病变进行评估，但仍未能明确诊断。最终通过超声引导下穿刺活检，证实为透明细胞肉瘤肝转移。
结论：综上，增强超声在肝转移瘤诊断中具有良好应用价值，结合患者相关病史或明确原发灶可提升诊断置信度。