7325 Adjuvant Denosumab Therapy For Adult-Onset Central Giant Cell Granuloma

Abstract Disclosure: S. Khalid: None. H. Whitlatch: None. Introduction: Central giant cell granulomas (CGCG) are rare, expansile non-neoplastic bone lesions involving the mandible or maxilla. These lesions consist of a mix of mononuclear and multinucleated giant cells in a mesenchymal stromal background. CGCG typically occurs before the age of 20 years and is more common in females. Conventionally, surgery has been the mainstay of treatment, ranging from curettage to aggressive resection. Unfortunately, curettage is associated with a recurrence rate of up to 49%. While surgical resection lowers recurrence rate to 6%, it can be associated with substantial morbidity, especially with larger lesions. This has led to the investigational use of medical adjunctive therapy, including intralesional corticosteroids, bisphosphonates, and calcitonin. Recently, there have been case reports involving the successful use of denosumab, a monoclonal antibody to receptor activator of nuclear factor-ΚB ligand (RANK-L). Here, we describe an unusual case of adult-onset CGCG treated with surgery and denosumab. CASE: A 24-year-old female presented to the oral maxillofacial surgery clinic with progressive left-sided mandibular swelling of 2 years duration. On examination, she was noted to have left lower third facial swelling and asymmetry. Intraoral exam showed buccal and labial expansion extending from tooth 19 to 27. CT scan revealed a large, multiloculated, expansile lytic lesion of the left mandible measuring up to 4.2 cm. Biopsy of the lesion was rich in giant cells, and the appearance favored giant cell granuloma. Biochemical evaluation included PTH 29 mg/dL (normal 15 mg/dL - 65 mg/dL), calcium 9.2 mg/dL (8.7 mg/dL -10.2 mg/dL), phosphorus 4.7 mg/dL (3 mg/dL -4.4 mg/dL) and alkaline phosphatase 94 mg/dL (44 mg/dL -121 mg/dL). She underwent enucleation and curettage of the lesion. 3 months after the surgery, she started her course of denosumab 120 mg weekly for 4 weeks, followed by monthly dosing with planned 1 year course. She noted improvement in pain after 2 doses of denosumab, and x-ray imaging at 1 month showed improved bone fill. Conclusion: Denosumab exerts its therapeutic effect in giant cell lesions by inhibiting osteoclast maturation, thereby suppressing osteolysis and giant cell formation. Our case suggests it could be considered first line adjuvant treatment for patients with large CGCG lesions. Presentation: 6/2/2024