Bone tumors

Giant cell tumor: Epiphysis -- benign -- female 20-40 -- distal femur, proximal tibia (knee) -- giant cell formation, in reaction to spindle-shaped mononuclear neoplastic cells. "Soap bubble" appearance on X-ray.

Osteochondroma: Metaphysis -- benign -- men 10-25 -- long bones -- exostosis, bone with cartilage cap. Transformation to chondrosarcoma is rare.

Osteosarcoma: Metaphysis -- malignant -- men 10-20 -- distal femur, proximal tibia (knee) -- has predisposing factors including Paget's, fibrous dysplasia, familial retinoblastoma, radiation, bone infarcts -- Codman's triangle due to elevation of periosteum. Poor prognosis.

Osteoid osteoma: Diaphysis-- benign -- men 10-20 -- Interlacing trabeculae of woven bone surrounded by osteoblasts -- less than 2cm and found in proximal femur and tibia.

Ewing's sarcoma: Diaphysis -- malignant -- men 10-20 -- anaplastic small blue cell tumor -- extremely aggressive with early mets but resposne to chemo -- "onion-skin" appearance on X-ray due to periosteal reaction -- 11:22 translocation -- long bones, pelvis, scapula, and ribs.

Enchondroma: Intramedullary -- benign -- men 20-50 -- cartilaginous -- usually in distal extremities.

Chondrosarcoma: Intramedullary -- malignant -- men 30-60 -- cartilaginous -- usually in pelvis, spine, scapula, humerus, tibia, or femur -- may be primary or develop from a osteochondroma (exostosis).