Presentation
Right leg pain and swelling in a young boy. No history of trauma reported.
Patient Data
There is an aggressive, malignant appearing lytic lesion in the shaft of the fibula.
Periosteal reaction:
- perpendicular spiculations producing a sunburst appearance in the center of the tumor
- there is also a laminated appearance towards the distal edge of the tumor producing an onion-skin appearance
- note the interrupted periosteal reaction (Codman triangle) at the proximal margin of the lesion
Associated soft tissue swelling.
- Codman triangle (Red arrow)
- Sunburst appearance (Blue arrows)
- Onion-skin periosteal reaction (Yellow arrow)
Case Discussion
Pathologically proven Ewing sarcoma.
Ewing sarcoma is an aggressive bone tumor observed in the first two decades of life. Second most common malignant bone tumor in children, presenting a higher prevalence in boys than in girls (3:1 ratio).
The typical clinical presentation includes:
- Pain and swelling at the site of the tumor. Pain often referred to the adjacent joint.
- Patients may present with nonspecific symptoms such as fever, increased erythrocyte sedimentation rate, and leukocytosis, or with weight loss and anemia.
Radiographic findings:
Mainly located near the metaphysis/diaphysis of long bones. Less often in flat bones or vertebral bodies.
Usually osteolytic lesions (motheaten, or permeative) with a soft-tissue component.
Periosteal reactions are common:
- Spiculation (periosteal new bone formation radiating into the soft tissues)
- Onionskin periosteal ossification.
- Codman triangle: elevated ossified periosteum at the margin of the subperiosteal tumor.
- "Sunburst" appearance
On imaging, the main differential diagnosis is osteosarcoma.
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