Giant cell tumor of the thoracic spine completely removed by total spondylectomy after neoadjuvant denosumab therapy

Abstract

Denosumab, a novel monoclonal antibody that targets the receptor activator of nuclear factor-κB (RANK) ligand (RANKL), has recently been used to treat patients with giant cell tumor of bone (GCTB). However, few reports have described the clinical results of denosumab therapy for spinal GCTB and evaluated treatment efficacy with respect to the entirety of the resected vertebra after denosumab therapy. We present the case of a 51-year-old man with T12 GCTB that was completely removed by a total spondylectomy following 10 courses of neoadjuvant denosumab therapy. Post-therapy radiological findings indicated epidural tumor reduction in the spinal canal and sclerotic rim formation. However, the affected vertebra collapsed despite denosumab therapy and a massive bridging callus formation was present between the spinal GCTB and adjacent vertebra. These morphological changes made the tumor margins unclear and increased the difficulty of dissection of the segmental arteries from the vertebral body and en bloc corpectomy by a posterior-approach. Pathological findings indicated increased woven bone at the peripheral lesion of the resected vertebra and RANKL-positive stromal cells remained around the woven bone. These findings support that GCTB stromal cells survived around the newly formed woven bone after long-term denosumab treatment and total surgical resection of such primary spinal lesions as the gold-standard treatment, even following administration of denosumab. Surgeons should note that prolonged adjuvant denosumab therapy may increase the difficulty of performing a posterior-approach total en bloc spondylectomy.