Parosteal osteosarcoma

Case contributed by Dr Ian Bickle


Fell off a stool and landed on the right side. Hit right leg on the bed, tender right proximal femur and tender swollen right knee. Reduced ROM, can't weight bear.

Patient Data

Age: 25 years
Gender: Female

Lobulated exophytic lesion arising from the cortex of the dorsal aspect of the metadiaphyseal region of the distal femur measuring 9 cm in length. Periosteal new bone formation at the lateral aspect of the distal femur raising concern. No bony destruction or soft tissue involvement identified.


4.8 x 4.9 cm exophytic juxtacortical mass arising from the posterior aspect diametaphyseal aspect of the distal femur. Relatively minor cortical destruction and periosteal reaction. The mass abuts the popliteal neurovascular bundle.

Trace of joint effusion.

No skip lesions in the proximal femur.

Case Discussion

Appearances are classical of parosteal osteosarcoma.

A tertiary bone center referral was made for the purposes of biopsy and management.

In the context of a fellowship examination, the statement of 'referral to a bone center' is a must.

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