Giant-cell tumor is a benign but locally aggressive primary bone tumor that requires surgical management. Most giant-cell tumors initially are demonstrated on radiographs as distal, subarticular, geographic osteolytic lesions. Abundant giant cells on histology are reactive secondary to a neoplastic fibroblast-like stromal cell. Giant cells are present in many neoplastic and non-neoplastic bone lesions; therefore the diagnosis of giant-cell tumors requires correlation of clinical, imaging, and pathologic data to exclude other lesions that demonstrate a similar histologic pattern. A small number of giant-cell tumors result in lung lesions, many of which have benign histology, can be treated by wedge resection, and do not affect long-term outcome. After adequate surgical curettage and the use of intraoperative surgical adjuvants, recurrence rates of approximately 10% are reported.