Periosteal reaction also known as periostitis, periosteitis or periosteal new bone formation, is a non specific radiographic finding that occurs with periosteal irritation can result from any of a large number of causes. The morphological appearance of periostitis can be helpful, but is usually not sufficiently specific to determine its cause. Establishing whether periosteal new bone formation is solitary versus multi-focal (or generalized) is useful in narrowing the diagnostic possibilities. Common causes of solitary periosteal new bone formation would include healing fractures, chronic stress injuries, subperiosteal hematomas (e.g., cephalohematoma), osteomyelitis, and bone tumors. The appearance of the adjacent bone will gives clues as to which of these is the most likely etiology.

Figure 1. Schematic diagram of periosteal reactions

Footnote: Schematic diagram of periosteal reactions, regardless of their cause. On top of this, there are complex or disorganized periosteal reactions, which could be a combination of any of these.

Types of periosteal reaction

Periosteal reactions may be broadly characterized as benign or aggressive (not benign and malignant), or more specifically broken down by pattern and based on the time course of the initiating process.

Benign periosteal reaction

Low-grade chronic irritation allows time for the formation of 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.

Aggressive periosteal reaction

Rapid irritative processes do 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.

Aggressive periosteal reactions can not only be seen with malignant tumors, but also with more benign processes like infection, eosinophilic granuloma (Langerhans cell histiocytosis), aneurysmal bone cyst, osteoid osteoma, hemophilia ¹ and trauma.

Morphological classification of periosteal reactions

More specific classification of periosteal reactions can be made to narrow the differential diagnosis:

single layer
multilayered
solid
spiculated
- perpendicular (hair-on-end)
- divergent (sunburst)
- sloping (velvet)
disorganized/complex
Codman triangle

Codman triangle periosteal reaction

Codman triangle is a type of periosteal reaction seen with aggressive bone 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) in aggressive lesions, so only the edge of the raised periosteum will ossify.

The Codman triangle may be seen with the following aggressive lesions:

Osteosarcoma
Ewing sarcoma
Osteomyelitis
Active aneurysmal bone cyst
Giant cell tumor
Metastasis
Chondrosarcoma (especially juxtacortical chondrosarcoma)
Malignant fibrous histiocytoma

Figure 2. Codman triangle periosteal reaction

Footnote: Codman triangle is a type of periosteal reaction seen with aggressive bone lesions, in this case an osteosarcoma.

Disorganized periosteal reaction

Disorganized or complex periosteal reaction has spicules with random orientation and appearance. It can be seen in highly aggressive processes:

osteosarcoma
metastasis
osteomyelitis
chondrosarcoma
Ewing sarcoma
stress fracture
malignant fibrous histiocytoma
spindle cell sarcoma

Sunburst periosteal reaction

Sunburst appearance is a type of periosteal reaction giving the appearance of a sunburst secondary to an aggressive periostitis. It should not be confused with the sunburst sign of meningioma vascularity.

The sunburst appearance occurs when the lesion grows too fast and the periosteum does not have enough time to lay down a new layer and instead the Sharpey’s fibers stretch out perpendicular to the bone. It is frequently associated with osteosarcoma but can also occur with other aggressive bony lesions such as an Ewing sarcoma or osteoblastic metastases (e.g. prostate, lung or breast cancer)

Figure 3. Sunburst periosteal reaction

Footnote: Case of osteosarcoma. A malignant bone tumor accounting for 20% of primary bone tumors. An ill-defined sclerotic area affecting the metaphysis of distal fibula with an aggressive periosteal reaction (sunburst type). This lesion involves the adjacent posterior aspect of the tibia and the calcaneum inferiorly. It is associated with a moderately large soft tissue swelling.

Multilayered periosteal reaction

Multilayered periosteal reaction, also known as a lamellated or onion skin periosteal reaction, demonstrates multiple concentric parallel layers of new bone adjacent to the cortex, reminiscent of the layers on an onion. The layers are thought to be the result of periods of variable growth ².

Multilayered periosteal reaction has been associated with:

osteosarcoma
acute osteomyelitis
Ewing sarcoma
Langerhans cell histiocytosis
hypertrophic osteoarthropathy

Figure 4. Multilayered periosteal reaction

Footnote: Osteoblastic metastases from prostate cancer presenting as knee pain in a 70 year old man. The distal femur and proximal tibia show a diffuse increase in density with a patchy texture. A lamellated periosteal reaction is observed circumferentially around the distal femoral metaphysis, however no focal area of cortical violation or associated soft-tissue mass is observed. It is a bit unusual to see a periosteal reaction with protate mets, or in any older individual for that matter because the periosteum is tightly adhered to bone and limited in its ability to react quickly or robustly to an underlying pathology. The blastic changes in this case however are none-the-less characteristic, and blastic mets from prostatic carcinoma must be the #1 differential diagnosis in an elderly male with patchy sclerotic bone changes.

Single layer periosteal reaction

Single layer periosteal reaction is a uniformly dense, single thin layer of new bone about 1-2 mm from the cortical surface. Passive hyperemia 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

Figure 5. Single layer periosteal reaction

Footnote: This leg x-ray shows periosteal reaction around tibia and fibula. There is also soft tissue calcification medial to the tibia. This patient had chronic venous disease of the lower limbs, and the soft tissue calcification probably represents phleboliths within varicose veins. Periosteal reaction due to venous stasis is typically solid and undulating, and initially separated from the cortex, as in this case.

Solid periosteal reaction

Solid periosteal pattern is thought to evolve from single layer and multilayered periosteal reactions, forming a solid layer of new bone adjacent to the cortex.

Solid periosteal reaction can be seen in:

osteoid osteoma
osteomyelitis
osteosarcoma
chondrosarcoma
fibrous dysplasia
non-ossifying fibroma
osteoblastoma
osteofibrous dysplasia
stress fracture
Brodie abscess
chondroblastoma
giant cell tumor
skeletal metastasis
Ewing sarcoma
simple bone cyst

Spiculated periosteal reaction

Spiculated periosteal reaction represents spicules of new bone forming along vascular channels and the fibrous bands that anchor tendons to bone (Sharpey fibers). A spiculated periosteal reaction signifies a rapid underlying process that prevents 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:

Perpendicular (hair-on-end)

Ewing sarcoma
osteosarcoma
metastasis

Divergent (sunburst)

osteosarcoma
hemangioma
osteoblastic metastasis
- prostatic
- bronchoalveolar
- carcinoid
- breast
- neuroblastoma (pediatric age group)
osteoblastoma

Focal slopping (velvet)

chondrosarcoma

Figure 6. Spiculated periosteal reaction

Symmetrical periosteal reaction

There are a large number of causes for a symmetrical periosteal reaction ³:

chronic venous insufficiency
hypertrophic osteoarthropathy
physiologic periostitis, most common cause before 6 months old
Caffey disease
juvenile idiopathic arthritis
pachydermoperiostosis
congenital syphilis
fluorosis
thyroid acropachy
dysproteinemia

Figure 7. Symmetrical periosteal reaction

Footnote: 5 month baby with irritable, mild fever, tenderness left thigh with visible swelling, was undergoing treatment for osteomyelitis. Lamellated to fusiform periosteal reaction along the shaft of left femur is evident with minimal soft tissue swelling. A subtle finding of periostitis along the right lower ribs is also seen, and child cried everytime he was held due to chest pain.

Generalized periosteal reaction

The list of causes of a generalized periosteal reaction overlaps that of symmetrical periosteal reaction, and includes ³:

vascular stasis (common)
congenital syphilis
fluorosis
Gaucher disease
hypertrophic osteoarthropathy
pachydermoperiostosis
hypervitaminosis A
infantile cortical hyperostosis (Caffey disease)
thyroid acropachy
tuberous sclerosis

Figure 8. Generalized periosteal reaction

Footnote: Radiographs showing an extensive bilateral periosteal reaction, more on the right side, associated with subcutaneous calcifications. This is a 67 year old female patient with a known history of diabetes mellitus, chronic kidney disease stage 5, and venous insufficiency. She was admitted by nephrology for dialysis and has a history of chronic lower limbs ulcers for more than four years.

Periosteal reaction causes

Periosteal reaction may be seen with the following lesions:

Osteosarcoma
Ewing sarcoma
Osteomyelitis
Active aneurysmal bone cyst
Giant cell tumor
Metastasis
Chondroblastoma
Chondrosarcoma (especially juxtacortical chondrosarcoma)
Malignant fibrous histiocytoma
Stress fracture
Spindle cell sarcoma
Langerhans cell histiocytosis
Hypertrophic osteoarthropathy
Early fracture healing
Osteoid osteoma
Aneurysmal bone cyst
Chronic venous insufficiency
Chondrosarcoma
Fibrous dysplasia
Non-ossifying fibroma
Osteoblastoma
Osteofibrous dysplasia
Brodie abscess
Simple bone cyst
Chronic venous insufficiency
Physiologic periostitis, most common cause before 6 months old
Caffey disease (infantile cortical hyperostosis)
Juvenile idiopathic arthritis
Pachydermoperiostosis
Congenital syphilis
Fluorosis
Thyroid acropachy
Dysproteinemia
Vascular stasis (common)
Congenital syphilis
Gaucher disease
Hypervitaminosis A
Tuberous sclerosis

Periosteal reaction treatment

Periosteal reaction treatment involves treating the underlying causes.

Wolfgang Dähnert. Radiology Review Manual. (2011) ISBN: 9781609139438[↩]
Selections from the buffet of food signs in radiology. Radiographics. 2002 Nov-Dec;22(6):1369-84. https://doi.org/10.1148/rg.226025521[↩]
Rana RS, Wu JS, Eisenberg RL. Periosteal reaction. AJR Am J Roentgenol. 2009;193 (4): W259-72. doi:10.2214/AJR.09.3300[↩][↩]