Primary denosumab therapy for a three-column pediatric cervical aneurysmal bone cyst: illustrative case

BACKGROUND: Pediatric spinal aneurysmal bone cysts (ABCs) involving all three columns present significant surgical challenges due to high procedural morbidity and vertebral artery risks. While denosumab is utilized off-label for these aggressive lesions, its efficacy and safety in pediatric spinal cases remain insufficiently characterized. OBSERVATIONS: A 12-year-old girl with a C6 ABC and progressive myelopathy (modified Japanese Orthopaedic Association [mJOA] score 14) underwent 12 months of primary denosumab therapy. Neurological recovery was rapid, with the mJOA score improving to 17 by the 2nd month. Serial imaging confirmed centripetal ossification and indirect cord decompression, while sagittal alignment remained stable. A structured review of 33 pediatric spinal ABC cases supported the role of denosumab in achieving early clinical and radiographic stabilization. LESSONS: Denosumab serves as a viable alternative for aggressive pediatric spinal ABCs when surgical morbidity is prohibitive. However, clinicians must monitor for severe rebound hypercalcemia following treatment cessation and potential late recurrence. Long-term surveillance is mandatory to ensure metabolic safety and evaluate the durability of the ossified bone matrix. https://thejns.org/doi/10.3171/CASE26396.