<prompt> The bone tumor seen in children with characteristic onion-peel periosteal reaction is?OsteosarcomaGiant cell tumorEwings sarcomaOsteoid osteoma  <response>: ANSWER: C Ewings sarcomaREF: Apleys system of orthopaedics 8h edition page 190, Tureks orthopaedics 6th edition page 307Repeat from June 2008EWINGS SARCOMA:Highly malignant, undifferentiated peripheral primitive neuro ectodermal tumor PENMost common site is diaphysis of femurCommon in 10-20 year old maleHistopathology shows round cells containing glycogen and reticulin; PAS positive and diastase digestable80-95 tumors possess translocation; tll; 22X Ray reveals laminated periosteal new bone formation also known as Onion peel appearance 