It is characterised by the production of osteoid directly from malignant spindle cell stroma. The knee and proximal humerus are common sites, and early diagnosis is difficult. A relatively painless mass is a frequent presentation. Primary tumours are further classified as central or juxtacortical. Enchondroma - Benign cartilaginous neoplasm arising in diaphyseal medullary cavities of long bones, possibly from epiphyseal plate remnants.
Enchondromas are asymptomatic and can be located in any bone, especially in the hands and feet.
These lesions represent a disorder of normal enchondral bone growth, and are usually sessile or pedunculated lesions arising from the cortex of a long bone adjacent to the epiphyseal plate. Tumour enlargement is common and ceases after maturity. It is commonly accompanied by leg length discrepancy, knee and elbow angular deformities, and other skeletal abnormalities. Osteochondromas develop in multiple metaphyses of affected children and they continue to increase in size and number until skeletalmaturity. Chondromyxoid Fibroma Chondroblastoma Chondrosarcoma - Second to osteosarcoma in prevalence of bony sarcoma's.