Exoscopic-Endoscopic Resection of Intramedullary Spinal Cord Metastasis From Renal Cell Carcinoma With Ventral Exophytic Extension

Intramedullary spinal cord metastasis (ISCM) is a rare manifestation of renal cell carcinoma (RCC). A 73-year-old man presented with left shoulder pain and left upper extremity weakness for two months. Magnetic resonance imaging (MRI) revealed intramedullary and intradural extramedullary lesions at the C5 level, compressing the spinal cord from the center of the cord and the left ventral side. Contrast-enhanced CT revealed a right renal mass and brain MRI showed no other lesions. Digital subtraction angiography showed a tumor stain from the anterior spinal artery and subsequent angioarchitecture of the intra- and extramedullary tumors. Following exoscopic resection of the extramedullary tumor, the intramedullary tumor was removed via a posterior midline myelotomy. The tumor surrounding the anterior spinal artery was intentionally left to prevent neurological deficits. The histopathological examination revealed metastatic clear cell RCC. Postoperative MRI revealed a small residual tumor ventral to the spinal cord. The nephrectomy for the right RCC was performed one month after the initial spinal surgery. Within the subsequent one month, the residual tumor rapidly increased in size. Reoperation with exoscopic-endoscopic techniques achieved complete tumor resection. The patient underwent radiotherapy to the C3-6 levels (30 Gy in 10 fractions) and pembrolizumab therapy. Postoperative MRI demonstrated no recurrence for four months, and the patient's symptoms remained in the same preoperative state. This case highlights the successful use of advanced minimally invasive techniques for treating ventrally exophytic ISCM from RCC.