PERIOSTEAL REACTION
PERIOSTEAL REACTION
- Periosteal reaction, also known as periostitis or periosteitis.
- It’s a non specific radiographic finding that occurs with periosteal irritation.
- Periosteal reactions may be broadly characterised as benign or aggressive, or more specifically broken down by pattern.
- Periosteal reaction results when cortical bone reacts to one of many possible insults.
- Tumor, infection, trauma, certain drugs, and some arthritic conditions can elevate the periosteum from the cortex and form various patterns of periosteal reaction
Types of Periosteal Reaction
- It has been classified in terms of continuous versus interrupted forms, single versus multiple layers, and aggressive versus nonaggressive subtypes.
- In evaluating periosteal reaction, the major goal is to recognize its presence rather than the specific subtype.
- Because there is significant overlap in the disease entities that result in the two major forms of periosteal reaction: aggressive and nonaggressive.
Nonaggressive
- Thin
- Solid
- Thick irregular
- Septated
Aggressive
- Laminated (onionskin)
- Spiculated
- Perpendicular/hair-on-end
- Sunburst
3. Disorganized
4. Codman triangle
Solid periosteal reaction
- Nonaggressive form that is primarily seen with benign, slow processes.
- A healed fracture, osteoid osteoma, and osteomyelitis can all exhibit solid periosteal reaction that appears as either thin or thick sheets


Onion peel or lamemmated appearance
- Multiple layers of new bone are formed concentrically around the cortex, producing a laminated or onionskin appearance.
- The laminated appearance is seen in a variety of lesions, including sarcomas, osteomyelitis, and chondroblastomas.

Spiculated pattern
- An aggressive form of periosteal reaction that includes both hair-on-end and sunburst subtypes.
- Spicules of bone form perpendicular to the periosteal surface in the hair-on-end subtype, which is highly suggestive of Ewing’s sarcoma.


- The linear spicules of new bone form along newly formed vascular channels and fibrous bands (Sharpey fibers).
- In the sunburst subtype of periosteal reaction, the spicules of new bone radiate in a divergent pattern instead of perpendicular to the cortex , an appearance often associated with conventional osteosarcomas.



Codman triangle
- A Codman triangle develops when a portion of periosteum is lifted off of the cortex by tumor, pus, or hemorrhage at a leading edge.
- This aggressive form of periosteal reaction is commonly seen in osteosarcomas and occasionally with infection and metastases.

Exam Important
- Periosteal reaction in a case of acute osteomyelitis can be seen earliest at 10 days.
- Sunray appearance on X – ray is seen in Osteosarcoma.
- Periosteal reactions is seen in Osteomyelitis, Syphilis & Tumor.
- Earliest radiological change to appear in case of acute osteomyelitis is Loss of plane between soft tissue and muscle.
- Acute osteomyelitis can best be distinguished from soft tissue infection by MRI.
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