Discussion:

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, like layers on an onion. The layers are thought to be the result of periods of variable growth and indicate a pathological process of intermediate aggressiveness.

Differential diagnosis for Onion peel appearance:

– Osteosarcoma
– Ewing sarcoma
– Acute osteomyelitis
– Langerhans cell histiocytosis (LCH)
– Hypertrophic osteoarthropathy