Osteosarcoma of zygoma

Case contribution: Dr Radhiana Hassan


  • A 33 years old Malay lady
  • presented with mass at the right eye
  • physical examination shows a huge orbital mass involving the supra orbital, forehead, temporal, preauricular and zygomatic region
  • proptosis of right eyeball with necrosis of cornea
  • hard and non tender, at certain areas it is crusted and inflamed.
  • deformity of lateral walls.
  • left eye is intact.
  • cervical nodes not palpable.

Radiographic findings:

  • Skull radiograph in OM projection shows soft tissue opacity overlying the right orbital region.
  • Ill-defined lytic lesion is also seen of the adjacent bone

CT scan findings:

  • A destructive lytic lesion of the right zygoma (red arrows) with huge surrounding soft tissue mass.
  • The soft tissue mass infiltrate the right orbital cavity causing right proptosis.
  • Infiltration of the right optic nerve and extra-ocular muscles sparing the right medial rectus.
  • Bony spiculations (yellow arrows) are noted within the mass radiating from the zygomatic bone.

Final diagnosis: Osteosarcoma of right zygomatic bone (HPE proven)


  • Osteosarcoma is a primary malignant neoplasm of the bones
  • greatest predilection for metaphyses of long bones
  • osteosarcoma of craniofacial bones is uncommon representing only 1% of tumours of head and neck region
  • the commonly involved bones in order of frequency are jaw bones, palate and skull vault. Involvement of zygomatic bone is rare
  • Typically occur in 3rd to 4th decades, equal sex distribution
  • radiologically 2/3 of craniofacial osteosarcoma is osteolytic
  • periosteal reaction is also not frequently reported in craniofacial osteosarcoma
  • Local recurrence is high and metastasis to other organs occurs rarely, unlike the long bones osteosarcoma
  • Five-year survival rate is 25%-35% after radical resection


Progress of patient:

  • started on chemotherapy
  • a repeat CT scan 2 months later shows reduction in the size of the mass
  • patient refused operation and opted for conservative management.
  • Last review patient presented with multiple lung metastasis
Author: radhianahassan