Case 2

I am presented with MRI and CT images of the knee and lower thigh.

I can appreciate eccentric cortical thickening or sclerosis at the lower diaphysis of the femur; there is high STIR signal and low T1 signal in the medullary bone or bone marrow around this area, indicating marrow oedema.

There is a small, round structure at the cortico-medullary interface which shows intermediate signal on both T1 and STIR images, central calcification on the CT series, and heterogeneous enhancement on the post-contrast images. 

These features are characteristic of an osteoid osteoma. I would inform the referring physician of the findings, and flag the case for discussion at orthopaedic MDT.

These lesions may be managed conservatively or by image guided intervention, which may include RF, microwave or cryo-ablation.