En bloc resection, including the cord for tumor-free margin, in a multilevel osteosarcoma of the spine: 20-year disease-free survival. Illustrative case.

backgroundOsteosarcoma (OS) is a rare malignant bone tumor, with 4% of cases affecting the spine. OS in the spine is as common as Ewing sarcoma in the spine, comprising 10%-15% of cases, and occurs more frequently in older adults in comparison with OS of the limb. The standard treatment for limb OS involves neoadjuvant chemotherapy followed by en bloc resection with tumor-free margins. The prognosis for OS of the spine is significantly worse than that for OS of the limbs. OBSERVATIONS: This case report details a 17-year-old female with OS arising at T11, who has achieved a 20-year disease-free survival. The tumor affected 5 vertebrae, leading to motor paraplegia (American Spinal Injury Association grade B). Neoadjuvant chemotherapy and tumor-free margin en bloc resection, including the canal's contents, were completed. LESSONS: The case suggests that the poorer prognosis in spinal OS compared with limb OS is mainly due to the inability to achieve tumor-free margin en bloc resection, due to severe functional loss. In this peculiar case, subtotal paraplegia at the time of diagnosis helped the patient understand that cord amputation would result in a better final outcome. In all cases in which intentional transgression is required to preserve functions, gross-total excision combined with accelerated particle radiotherapy is an option, but long-term follow-up is still unclear. https://thejns.org/doi/10.3171/CASE24771.