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

Abstract

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.

Keywords: cervical; endoscope; exoscope; intramedullary spinal cord metastasis; radiotherapy; renal cell carcinoma.

Figure 1. Preoperative and intraoperative findings during the first surgery

(a) Initial sagittal contrast-enhanced gadolinium (Gd) magnetic resonance imaging (MRI), showing an enhanced ventral mass at the C5 level. (b) Initial axial Gd MRI showing a continuous intra- (black arrowhead) and extramedullary mass (white arrowhead). (c) Sagittal T2-weighted MRI showing hyperintensity from the medulla oblongata to the mid-thoracic spinal cord. (d) Contrast-enhanced computed tomography (CT) showing an enhanced cervical spinal cord mass and a right renal mass. (e) Lateral right vertebral angiogram showing the tumor stain involving the anterior spinal artery. (f) 3D rotational angiography of the right vertebral artery showing the stain of an intra- and extramedullary mass fed by the right radiculomeningeal artery (arrow) and anterior spinal artery (arrowhead). (g) Intraoperative exoscopic view showing an extramedullary hypervascular tumor ventrolateral to the cervical spinal cord and the nerve roots. (h) Intraoperative exoscopic view after midline myelotomy showing an intramedullary tumor. (i) The hematoxylin-eosin stain showing clear or eosinophilic cytoplasm due to glycogen and lipid accumulation, with well-defined cell borders and a nested or alveolar growth pattern surrounded by a delicate vascular network (a scale bar = 100 μm). (j) Immunohistochemical stain with PAX8, showing strong nuclear positivity, confirming their renal origin and distinguishing RCC from other neoplasms (a scale bar = 200 μm).

Figure 2. Preoperative, intraoperative, and postoperative findings at the second surgery

(a) Axial contrast-enhanced gadolinium (Gd) magnetic resonance imaging (MRI) after the first surgery showing a small residual tumor ventrolateral to the cervical spinal cord. (b) Axial Gd MRI two months after the first surgery showing an enlarged residual tumor. (c) Intraoperative exoscopic view showing the recurrent tumor ventrolateral to the spinal cord. (d, e) Intraoperative exoscopic view and endoscopic view showing resection of the residual tumor adhesive to the ventral spinal cord with the simultaneous multi-angle view. (f, g) Postoperative axial and sagittal Gd MRI showing total removal.