Periosteal Reaction and Its Types

Last Updated on October 27, 2023

Periosteal reaction is the formation of new bone after trauma or some other pathology from the periosteum as visualized on the radiographs. The periosteum is a membrane that covers bones except in the cartilage part. Periosteal reaction is also known as periostitis.

When an insult occurs, vascular proliferation and thickening of the normal periosteum occur as a response. The morphology of periosteal reaction suggests the intensity, duration, and aggression of the trigger.

On radiographs, it usually takes between 10-21 days for the periosteal reaction to become visible as visualization occurs after a certain degree of mineralization.

The periosteal reaction can be termed as benign or aggressive, or a more specific classification system can be used.

Benign and Aggressive Periosteal Reaction

It occurs in cases of low-grade persistent irritation to the periosteum and periosteum has enough time to form normal or near normal cortex. The cortex will be thick and dense and have a wavy or uniform appearance. Benign periosteal reactions can be seen in callus formation in a fracture or with slowly growing tumors.

If the process is rapid, it does not allow the periosteum time to lay down and consolidate new bone to form normal cortex. The cortex may appear lamellated, amorphous, or sunburst-like. [see below]

Morphological Classification of Periosteal Reaction

More specific classification of periosteal reactions is

Single layer
Multilayered
Solid
Spiculated – perpendicular (hair-on-end), divergent (sunburst), sloping (velvet)
Disorganized/complex
Codman triangle

Single Layer Periosteal Reaction

In this type of periosteal reaction, a uniformly dense, single thin layer of new bone about 1-2 mm from the cortical surface is formed. Increase in blood supply causes increased osteoblastic activity and production of new bone. It is seen in

Premature infants for up to 6 months
Early fracture healing
Osteosarcoma
Osteomyelitis
Langerhans cell histiocytosis
Metastasis
Osteoid osteoma
Aneurysmal bone cyst
Ewing sarcoma
Giant cell tumor
chronic venous insufficiency

Multilayered Periosteal reaction

It is also known as a lamellated or lamellar or onion skin periosteal reaction because of multiple concentric parallel layers of new bone like the layers on an onion. This occurs with fast-growing processes as the periosteum cannot produce new bone as fast as the lesion is growing leading to intermittent bouts of bone formation, unlike solid continuous bone formation.

The pattern of interrupted periosteal reaction varies depending upon the growth of the lesion.

With malignant tumors, the spaces between the layers may become secondarily infiltrated by malignant cells.
Found in

Osteosarcoma
Acute osteomyelitis
Ewing sarcoma
Langerhans cell histiocytosis (LCH)

Solid Periosteal Reaction

This occurs with slow-growing processes, as the periosteum in such cases the periosteum has plenty of time to respond to the process and can produce new bone just as fast as the lesion is growing leading to solid, uninterrupted periosteal new bone formation.

The cortex will be thick and dense and have a wavy or uniform appearance.

It can be seen in-

Osteoid osteoma
Osteomyelitis, Brodie abscess
Fibrous dysplasia, Non-ossifying fibroma
Chondrosarcoma, Osteosarcoma
Osteoblastoma, Chondroblastoma
Osteofibrous dysplasia, Giant cell tumor
Metastasis
Ewing sarcoma
Simple bone cyst

Spiculated Periosteal Reaction

In a spiculated pattern, the periosteal reaction is perpendicular to the bone cortex. Spicules are not neoplastic and originate from the ossification along periosteal vascular channels and fibrous bands. A spiculated periosteal reaction signifies a rapid underlying process that prevents the formation of new bone under the raised periosteum.

The orientation of the spicules reflects the direction of tumor growth. Spiculated periosteal reactions can be divided into subtypes based on the orientation of the spicules.

sunburst-periosteal-reaction — Sun Burst Pattern of Periosteal Reaction in Osteosarcoma| Image Credit: Radiopaedia

Perpendicular (hair-on-end pattern) – Ewing sarcoma, osteosarcoma, metastasis
Divergent (sunburst pattern) – Osteosarcoma, hemangioma, Osteoblastic metastasis, osteoblastoma
Focal slopping (velvet) – Chondrosarcoma

Disorganized Periosteal Reaction

This has spicules with random orientation and appearance. It can be seen in highly aggressive processes like osteosarcoma, metastasis, osteomyelitis, chondrosarcoma, malignant fibrous histiocytoma, spindle cell sarcoma, Ewing’s sarcoma

Codman Triangle

With aggressive lesions, the periosteum does not have time to ossify with shells of new bone (e.g. as seen in a single layer and multilayered periosteal reaction), so only the edge of the raised periosteum will ossify at an angle with cortex.

The Codman triangle may be seen with