Locally administered zoledronic Acid therapy for giant cell tumor of bone.

Giant cell tumor of bone is locally aggressive and occurs in the meta-epiphyseal region of long bones. Because of its high recurrence rate, local adjuvant therapies such as phenol or liquid nitrogen have been recommended. In the present study, zoledronic acid, a nitrogen-containing bisphosphonate, was administered locally as an adjuvant during a biopsy. An otherwise healthy 43-year-old man presented with pain and swelling in the right knee. Plain radiographs showed an osteolytic lesion of the right proximal tibia. An open biopsy was performed and the intraoperative pathologic diagnosis was giant cell tumor of bone. Following biopsy, the defect was filled with betatricalcium phosphate, and 4 mg of zoledronic acid was locally administered into the tumor lesion. Two months after the biopsy, curettage and bone grafting were performed. Sections were obtained during the curettage for histology to evaluate the response to bisphosphonate treatment. Histologic examination revealed massive tumor cell death in the lesion in which both stromal cells and osteoclast-like giant cells were necrotic. Curettage was performed and the defect was filled with a commercial preshaped hydroxyapatitetricalcium phosphate bone substitute. Eighteen months after curettage, the patient had regained full range of motion and good function of the knee, and radiographs at 18 months after curettage revealed no recurrence of giant cell tumor of bone.