• Rare, low-grade, malignant tumor
  • Most common in 20- to 40-year-olds
  • Generally found in epiphysis or metaphysis of long bone, particularly proximal femur and humerus
  • Radiographic presentation:
    • Geographic osteolytic lesion at end of long bone
    • Cortex generally intact, but may be expanded
    • Often has sharp sclerotic margins; exception: larger lesions, which may have indistinct margins
    • Calcification within lesion uncommon
  • Microscopic presentation:
    • Admixture of clear cells, chondroid matrix, and giant cells
    • Ossification may be present
  • Tumor may resemble a benign tumor radiologically (such as chondroblastoma); however, can metastasize and must be treated with wide resection