Radiological features of the osteosarcoma -a) New bone formationb) Sun ray appearancec) Codman's triangled) Soap bubble appearancee) Onion pool appearance
X-ray of a patient with osteosarcoma shows following features : -

1)An area of irregular destruction in the metaphysis, sometimes overshadowed by the new bone formation. The cortex overlying the lesion is eroded. There is new bone formation in the matrix of the tumour.
2)Periosteal reaction : - As the tumor lifts the periosteum, it incites an intense periosteal reaction. The periosteal reaction in an osteosarcoma is irregular, unlike in osteomyelitis where it is smooth and in layers.
3)Codman's triangle : - A triangular area of subperiosteal new bone is seen at the tumour host cortex junction at the ends of the tumor.
4)Sun-ray appearance :- As the periosteum is unable to contain the tumour, the tumour grows into the overlying soft tissues. New bone is laid down along the blood vessels within the tumour growing centrifugally, giving rise to a ‘sur-ray appearance' on the X-ray.
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