Microsurgical resection of an intramedullary metastasis of rare histopathology-a case report and comprehensive literature review.

Background: Intramedullary spinal cord metastases (ISCMs) are rare manifestations of systemic malignancy, accounting for 4-9% of central nervous system metastases. Radio- and chemotherapy are considered first-line therapies. However, certain clinical presentations may require microsurgical resection of ISCM. The optimal treatment strategy remains controversial, particularly in cases with diagnostic uncertainty or rapid neurological deterioration. Case Description: We present a 59-year-old female patient with history of treated breast cancer who developed progressive, burning pain in the left groin radiating to the ventral thigh and knee, accompanied by sensory deficits and gait instability. Magnetic resonance imaging (MRI) revealed a contrast-enhancing intramedullary lesion at T10 with extensive perifocal edema from C7 to L1. Given the unclear etiology and worsening neurological symptoms, microsurgical resection was performed using intraoperative neuromonitoring and ultrasound guidance. Histopathological examination unexpectedly revealed a metastasis from a previously undiagnosed amelanotic melanoma, rather than the suspected breast cancer metastasis. Subsequent screening identified an additional right inguinal lymph node metastasis, which was surgically removed. The patient received adjuvant radiation therapy to T9-11 (13×2.5 Gy) and immunotherapy with nivolumab. At 3 years post-operation, the patient maintains good functional status with no evidence of tumor recurrence. Conclusions: This case highlights the value of microsurgical resection in providing both therapeutic benefit and definitive diagnosis and the importance of comprehensive histopathological evaluation even when a likely primary tumor exists. Larger, multicenter data collections are required to better delineate the role of microsurgery in ISCM treatment and to establish evidence-based guidelines for patient selection.