On plain radiograph, periosteal reaction with a 'Codman triangle' is most specifically indicative of:
- A Ewing's sarcoma with onion-skin periosteal pattern
- B Aggressive bone lesion causing rapid periosteal elevation before calcification ✓
- C Reactive bone formation in osteoid osteoma
- D Subperiosteal hematoma in scurvy
Explanation
Codman triangle represents the elevated periosteum at the margin of an aggressive lesion — the tumor grows so rapidly that the periosteum is elevated and the portion under the periosteum ossifies at the periphery, while the central portion remains unossified, creating a triangular lucency at the tumor margin. It is not specific to any single diagnosis but indicates aggressive biology (osteosarcoma being the classic). Ewing's shows concentric onion-skin periosteal layers. Osteoid osteoma has reactive cortical sclerosis. Scurvy periosteal changes are due to subperiosteal hemorrhage without the triangle pattern.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.