An osteosarcoma is a malignant tumour containing cells of mesenchymal origin and which is characterised by the formation of malignant osteoid. Osteosarcomas are the most common primary bone sarcoma, but osteosarcomas also (rarely) occur in bone – in other words the prefix “osteo-” relates to the production of osteoid matrix rather than an origin in bone.
- Incidence is around 1-2 per million per annum, which is around 131 new cases in England per annum
- Osteosarcomas have a peak incidence in the second decade of life, and a smaller peak in the elderly
- They classically occur in the metaphyseal regions of long bones where most growth occurs (ie distal femur, proximal tibia, proximal humerus)
The WHO histological classification of osteosarcoma recognises the following groups:
1. Central (Medullary) tumours
- conventional central osteosarcomas (the most common type)
- telangiectatic osteosarcoma
- intraosseous well-differentiated (low-grade) osteosarcomas
- small-cell osteosarcomas
2. Surface (peripheral) tumours
- parosteal (juxtacortical) well-differentiated (low-grade) osteosarcomas
- periosteal osteosarcoma: low to intermediate-grade osteosarcoma
- high-grade surface osteosarcoma
References:
Bone Sarcomas: incidence and survival rates in England – NCIN Data Briefing. National Cancer Intelligence Network 2010.
