Role of Denosumab in Endoscopic Endonasal Treatment for Juvenile Clival Giant Cell Tumor: A Case Report and Review of the Literature.

BACKGROUND: Giant cell tumors (GCTs) are histologically benign bone neoplasms with a locally aggressive nature that primarily occur in the epiphyses of the long bones. A small proportion of these tumors, however, occur in the pelvis, spine, or skull bones. Among these, GCTs of the skull base cannot be completely resected and require adjuvant therapy. We report a juvenile case of clival GCT that was successfully treated by endoscopic endonasal transsphenoidal surgery and subsequent adjuvant therapy with denosumab, a monoclonal antibody to receptor activator of nuclear factor-κB ligand. CASE DESCRIPTION: A 16-year-old boy was admitted to our hospital with progressively intolerable headache and right oculomotor nerve palsy. Computed tomography and magnetic resonance imaging showed a large tumor mass in the sphenoid sinus with extensive erosion of the clivus and compression of the right cavernous sinus. The tumor was resected by endonasal transsphenoidal surgery and histologically diagnosed as GCT. The giant cells showed positive immunostaining for CD68 and Mib-1 labeling index was less than 1.0%. Postoperative course was uneventful and the oculomotor disturbance was markedly improved. However, magnetic resonance imaging 2 weeks after surgery revealed marked enlargement of the tumor. Adjuvant therapy with denosumab was therefore initiated, resulting in marked reductions in tumor size.
CONCLUSIONS: This is the first report to describe beneficial effects of denosumab in the treatment of GCT of the skull base.