A 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 .
It can be seen with:
Langerhans cell histiocytosis (LCH)
Ewing sarcoma - distal femur - “Ewing sarcoma of the distal femur in a 9 year old boy with onion skin periosteal reaction.