There is a sessile osteochondroma in the left femur metaphyseal region medially and typically projecting away from the epiphysis. There is a low to intermediate T1W signal mass around the exostosis. The mass lesion is iso- to slightly hyperintense compared to muscle. The cartilage cap is thick with rings and arcs calcification and there is irregular subchondral bone. The lesion is noted within the vastus intermedius muscle. The mass is distant to the femoral neurovascular bundles.
The appearances are in keeping with an osteochondroma (exostosis) of the femur. The presence of aggressive features such as bony destruction, large soft tissue component are suggestive of malignant transformation.