[Rebound hypercalcemia after denosumab therapy in a 13-year-old boy with an aneurysmal bone cyst of the humerus-a case report].

Denosumab is approved for the treatment of osteoporosis and selected bone tumors, with its efficacy well documented in the literature. However, its use in children for benign bone tumors remains off-label. We report the case of a 13-year-old boy with an aneurysmal bone cyst of the humerus who developed severe hypercalcemia following the cessation of supportive denosumab therapy. The patient was successfully treated with intravenous fluid therapy, potassium supplementation, zoledronate, and furosemide. This case highlights the necessity for close monitoring of calcium and bone metabolism in children and adolescents during and after denosumab treatment.