Postoperative Denosumab Therapy in Aneurysmal Bone Cysts and Osteoblastomas: A Case Series and Review of Current Literature.

Denosumab, a monoclonal antibody targeting receptor activator of nuclear factor-kappa B ligand (RANKL), has demonstrated efficacy in giant cell tumors of bone and has been increasingly explored as a treatment option for aneurysmal bone cysts (ABCs) and osteoblastomas. While its use as a neoadjuvant therapy has been documented, its postoperative role remains unclear. This study presents two cases in which denosumab was administered after surgical resection to evaluate its potential for recurrence prevention and bone remodeling. The first patient, a 36-year-old female, was diagnosed with a spinal ABC at the T11 level. She underwent curettage, corpectomy, and anterior-posterior spinal instrumentation. Postoperatively, she received denosumab at 120 mg weekly for the first month, followed by 120 mg monthly. At the one-year follow-up, there was no evidence of recurrence, metastasis, or tumor regrowth. The second patient, a 21-year-old woman diagnosed with pelvic osteoblastoma in the left sacrum, underwent curettage and reconstruction with iliac fixation. Approximately 15 months after surgery, she began denosumab therapy, receiving a total of 10 doses, with three doses in the first month (on days 1, 15, and 28), followed by one dose per month at 120 mg. After three years of follow-up, she remained free of recurrence or metastasis, suggesting possible long-term disease control. These cases highlight the potential role of postoperative denosumab therapy in preventing recurrence and supporting bone remodeling following surgical treatment of ABCs and osteoblastomas. While both patients remained disease-free, the lack of standardized protocols for postoperative denosumab use remains a significant limitation. The optimal timing, dosage, and duration of therapy are yet to be determined. Furthermore, concerns regarding potential complications, such as rebound hypercalcemia upon discontinuation, warrant further investigation. Long-term follow-up and larger studies are necessary to establish clear guidelines and determine whether denosumab can be a reliable adjuvant therapy in the postoperative management of these rare bone tumors.