Osteosarcoma

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.