18 - primary malignant bone tumors

What are the common primary malignant bone tumors?

• Osteogenic sarcoma
• Ewing's sarcoma
• Fibrosarcoma
• Chondrosarcoma

Primary bone tumors are rare, accounting for less than 1% of all malignant tumors.

What are the useful imaging modalities to investigate primary bone tumors?

• Plain radiographs
  • Plain radiographs can often predict the probable histology of a potentially malignant bone lesion.
• MRI
  • MRI is the imaging procedure of choice to evaluate primary bone tumors.
  • MRI is invaluable in surgical planning as it demonstrates the intraosseus and soft tissue involvement of the tumor and tumor extension.
  • MRI is also helpful in evaluating possible malignant degeneration of osteochondromas by allowing accurate measurements of the cartilage cap.
• CT
  • CT scans are generally less useful than MRI for assessing primary bone tumors.
  • CT is helpful in defining the integrity of the cortex and distribution of calcification.

What are the imaging findings of primary bone tumor?

• Osteogenic sarcoma
  • Destruction of bone
  • Sunburst appearance
  • Periosteal elevation
    • MR
    • Bone scan
  • Sclerosis

Osteogenic sarcoma fibula Destruction of bone with sunburst appearance.

Osteogenic sarcoma Tibia Sunburst appearance Aggressive periosteal reaction Sclerosis

Osteogenic sarcoma tibia Black Arrowheads : Destroyed cortex.

Osteogenic sarcoma tibia

• Chondrosarcoma
• Mass with calcification
• On plain radiographs, chondrosarcoma is a fusiform, lucent defect with scalloping of the inner cortex and periosteal reaction.
• Extension into the soft tissue may be present as well as punctate or stippled calcification of the cartilage matrix.

Chondrosarcoma Inferior ramus of pubis Calcified cartilaginous mass arising from a flat bone in a patient with unfused epiphyses.

Chondrosarcoma MR: White arrows : Mass with calcification. Arrowhead is pointing to femur.

• Ewing's Tumor
  • Lytic lesion
  • "Onion peel" appearance of periosteal reaction

Ewings Sarcoma Femur Arrow : Lytic lesion Arrowhead: "Onion peel" appearance of periosteal reaction.