The Role of Denosumab Treatment in Recurrent Giant Cell Bone Tumor of the Orbit.

Giant cell tumor of the bone (GCTB) is a rare primary bone neoplasm, representing about 5% of all primary bone tumors. Most GCTBs are found in the epiphysis of long bones, with only 2% of GCTBs involving the skull. In recent years, the receptor activator of nuclear factor Kappa ligand monoclonal antibody denosumab has been demonstrated as a promising therapeutic option for GCTB; however, this is an evolving field. We present a case of a 57-year-old female with a rare GCTB in the right orbit and sinuses, originally thought to be an aneurysmal bone cyst. Her symptoms included proptosis, intermittent blurry vision, sinus congestion, and frontal headaches. After excision, the tumor recurred within 18 months. Upon repeat excision, a diagnosis of GCTB was made. The patient started denosumab therapy and had no tumor growth over the ensuing 2 years, with stability of symptoms and clinical signs on follow-up.