Laminated periosteal reaction | Radiology Signs

Laminated periosteal reaction is caused by a pathological process that stimulates the periosteum to form multiple concentric layers of new bone around the cortex. It is typically seen in conditions associated with variable bone growth rates such as infections (e.g., osteomyelitis), malignant tumors (e.g., Ewing sarcoma, osteosarcoma), and some benign lesions (e.g., chondroblastoma, Langerhans cell histiocytosis). This reaction reflects an intermediate aggressiveness lesion, where the periosteum is intermittently stimulated to produce new bone layers.

Why is it called so?

The term “laminated” or “lamellated periosteal reaction” refers to the appearance of multiple layered shells of new bone growing concentrically on radiographic imaging, resembling the layers of an onion. It is also known as “onion skin periosteal reaction” due to this characteristic multilayered pattern.

Pathophysiology

The laminated pattern develops because the periosteum undergoes repeated cycles of stimulation. Each new layer of bone lifts the periosteum slightly away from the cortex, triggering the inner cambium layer to form another new bone layer beneath it. Another mechanism involves modulation of fibroblasts in adjacent soft tissues, which acquire osteoblastic activity to form successive sheets of new bone. This cyclical periosteal response results in multiple distinct layers of bone deposited over time, visible as concentric rings on imaging.

Alternative names: Onion skin periosteal reaction, multilayered periosteal reaction, lamellated periosteal reaction

Other associated named signs: None specifically linked; spiculated periosteal reactions (hair-on-end, sunburst) may be seen in related aggressive bone pathologies but represent different patterns.