Osteosarcoma

Osteogenic osteosarcoma. This 17 year old girl presented with knee pain, and her radiograph shows the classic appearance of osteosarcoma. There is increased density in the distal femur due to bone production by the tumour, and there is extension of the tumour through the cortex anteriorly (yellow arrows) resulting in interrupted periosteal reaction, i.e. a Codman triangle (white arrow).