Intermediate grade chondroblastic osteosarcoma arising from surface of long bones
Extremely rare
- 1% of all osteosarcomas
- 25% of surface osteosarcomas
Age 15-25
Typically anterior proximal tibia
- diaphysis of major long bones
- humerus
Primary malignancy arising from remnants of the notochord
Rare malignant tumour
Middle-aged adults (50-70)
M>F
In midline in axial skeleton
Base of skull 35%
Vertebrae 15%
- especially cervical
Sacrum 50%
4th most common STS
- 10-35% of STS
Peak age 3rd-4th decade
- rare in children
Cellular characteristics suggest tumour arises from primitive synovial cells
- rarely actually occurs within joint
Occasionally metastasis to lymph nodes (5-7%)
- like Epitheloid Sarcoma
Non Ossifying Fibroma
A hamartomatous defect in the metaphyseal cortex of skeletally-immature adolescents
Fibrous cortical defect
- < 2cm in diameter
Non ossifying fibromas
- > 2cm
Rare cartilage tumour
1% of bone tumours / rare
- typically in adolescents
Usually benign
- but aggressive / frankly malignant behaviour reported
- locally aggressive
- can have pulmonary metastasis