Denosumab in Spinal Osteoblastoma: A Systematic Review of Reported Cases

Background/Objectives: Denosumab has been reported as an adjunctive or alternative treatment for selected aggressive benign bone tumours, but its role in spinal osteoblastoma remains unclear. This systematic review aimed to summarise the reported indications, clinical and radiological outcomes, impact on surgical management, follow-up, and adverse events associated with denosumab use in spinal osteoblastoma. Methods: This systematic review was conducted in accordance with PRISMA 2020 and registered in PROSPERO (CRD420261435165). We searched PubMed/MEDLINE, Scopus, and Web of Science from inception to 30 September 2026, supplemented by a Semantic Scholar search and screening of relevant references. Eligible studies reported histologically confirmed spinal osteoblastoma treated with denosumab. We descriptively synthesised clinical, neurological, radiological, surgical, oncological, and safety outcomes. We assessed methodological reporting using Joanna Briggs Institute critical appraisal tools. Results: We included seven studies comprising 13 unique patients. Denosumab was used as neoadjuvant, stand-alone, postoperative, or salvage treatment. All 12 patients with evaluable radiological outcomes showed increased tumour mineralisation, ossification, or sclerosis (12/12). However, only three patients showed reductions in tumour dimensions, based on paired numerical measurements. All eight patients with available pain outcomes reported improvement (8/8). Post-treatment histopathology was available in two patients, and denosumab was reported to facilitate surgical resection in selected cases. No recurrence was reported during the available follow-up, although safety reporting was limited. These findings are based on published case reports and small case series and should therefore be interpreted with caution. Conclusions: Published reports describe increased tumour mineralisation or sclerosis and symptomatic improvement following denosumab treatment in patients with spinal osteoblastoma. Nevertheless, the available evidence is primarily derived from uncontrolled case reports and small case series and is therefore susceptible to publication and selective reporting bias. Current evidence does not conclusively establish treatment efficacy, define the optimal timing or duration of therapy, demonstrate improved surgical outcomes, clarify outcomes following treatment discontinuation, or adequately characterise long-term safety. Further multicentre studies are needed to provide more robust and systematic evidence.