Periosteal Osteosarcoma

  • Unusual tumour in adolesence
  • Rare +++
  • Higher grade
  • Typically Anterior Tibia or Humerus
    • Diaphyseal preference
  • Predominantly cartilage forming & mistaken for chondrosarcoma

Pathology

  • Typical with abundant cartilage formation (cf. parosteal OS) & cellular stroma
  • Malignant osteoid differentiates from chondrosarcoma

Radiology

  • X-ray
    • Ill-defined swelling with periosteal new bone formation
    • Sunburst appearance
    • Usually midshaft of tibia & femur in children
    • Small at time of presentation usually
    • Arises deep to periosteum
      • Often has flatter (often saucer-shape) appearance than parosteal OS
      • No separation from underlying cortex

Treatment

  • Wide excision
  • Neoadjuvant & Adjuvant Chemotherapy
  • DXRT stop local recurrence
  • Prognosis better than conventional but not as good as parosteal OS