Functional Outcome of Curettage and Chemical Cauterization with Bone Grafting and Fixation with Neo-Adjuvant Denosumab Therapy in a Case of Giant Cell Tumor of Navicular Bone of a Young Adult - A Case Report.

INTRODUCTION: Giant cell tumor of bone (GCTB) is an uncommon benign primary bone tumor that mainly affects the long bones. Its occurrence is most frequent in patients between 30 and 40 years old. Curettage and bone grafting mainstay of treatment but lesions with large extent and unclear margins require meticulous planning and comparatively morbid procedures. A locally aggressive primary bone tumor that contains numerous osteoclasts formed from marrow-derived precursors through receptor activator of nuclear factor κ-B ligand (RANKL). Denosumab is immunoglobulin G2 monoclonal antibody which stops differentiation of osteoclast-like giant cells and consequent osteolytic damage by binding RANK-L.

CASE REPORT: A 26-year-old female with complaints of pain in the right foot for 1 year, swelling in the right foot for 6 months, unable to bear weight on the affected foot with tender hard swelling present over the dorsomedial aspect of the right foot with inversion and eversion of the foot painful.Computed tomography scan and magnetic resonance imaging modalities revealed an expansile lesion in the navicular bone lobulated extension of lesion on the plantar aspect and adjacent tarsal bones and intertarsal joints. Histopathological report of the lesion determined giant cell tumor (GCT).After diagnosis of GCT established plan for excision of the lesion using curettage and chemical cauterization taken. More stable fixation; fill the void of excision bone grafting along with plate (3.5 mm combihole plate) fixation done Neo-adjuvant denosumab therapy given intraoperatively + regular intervals (denosumab 120 mg on day 0, 8, 15, 28). With informed consent patient was regularly followed annually, half year analysis of the patient reported a significant reduction in pain and no new increase of size in swelling or any new swelling. Adverse effect: Muscular pain and fatigue often encountered with denosumab therapy not seen in the patient.

CONCLUSION: Denosumab leads to downsizing of the tumor and leads to fibrosis of the margin and inhibiting the progress of the disease. Planned resection may become less morbid when preoperative denosumab is administered. En bloc resection of GCTB, especially in the case of soft-tissue involvement, can be facilitated by a neoadjuvant denosumab regimen.Strong evidence for the effect of denosumab for non-resectable GCTB.Optimal treatment duration and maintenance dose and interval of denosumab in unresectable disease are still under analysis.