A benign, chondroid-producing, well-circumscribed, lytic neoplasm usually arising from the epiphysis of long bones. It is characterized by the presence of chondroblasts, osteoclast-like giant cells, chondroid formation, calcification, and mitotic activity. In aggressive cases, there is rearrangement of the 8q21 chromosome band. It occurs most frequently in children and young adults and rarely metastasizes.

A usually benign tumor composed of cells which arise from chondroblasts or their precursors and which tend to differentiate into cartilage cells. It occurs primarily in the epiphyses of adolescents. It is relatively rare and represents less than 2% of all primary bone tumors. The peak incidence is in the second decade of life; it is about twice as common in males as in females. (From Dorland, 27th ed; Holland et al., Cancer Medicine, 3d ed, p1846)

A chondroblastoma is a rare, usually benign, tumor of bone that accounts for approximately 1% of all bone tumors. In 1931, Codman classified it as a chondromatous variant of giant cell tumors, when he described these lesions in the proximal humerus.