Periosteal Reaction: Radiographic Patterns
Orthopedic Oncology & Radiology: NEET PG High-Yield
1. Classification of Periosteal Reactions
| Pattern | Clinical Association |
|---|---|
| Solid (Continuous) | Usually benign; seen in osteoid osteoma, healing fractures, or chronic osteomyelitis. |
| Lamellated (“Onion-skin”) | Aggressive; classic for Ewing Sarcoma (also seen in osteomyelitis). |
| Sunburst / Spiculated | Very aggressive; classic for Osteosarcoma. |
| Codman Triangle | Aggressive; periosteal lifting due to rapid tumour growth (Osteosarcoma). |
2. High-Yield NEET Pearls
- Benign vs. Aggressive: Continuous/solid periosteal reactions generally suggest slow-growing processes, while interrupted (lamellated, sunburst, Codman) reactions indicate aggressive malignant processes.
- Codman Triangle: It is not a tumour, but a sign. It occurs when the tumour grows faster than the periosteal response can ossify, leaving an elevated triangular cuff of bone.
- Differential Diagnosis: Always consider osteomyelitis when you see a lamellated reaction, as it can mimic Ewing Sarcoma radiographically (“the great mimicker”).
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