This is an example of an enchondroma with a typical location in the femoral metaphysis. They are typically characterized by the following imaging findings as in this case:

• sharply defined margins

• narrow transition zone

• rings and arcs calcification

As visible in this case, they can also grow. The main differential of enchondroma is low-grade chondrosarcoma. The latter usually shows more aggressive features including more severe endosteal scalloping, expansile remodeling, cortical breakthrough, larger size (>5-6cm) and pain.

This case also displays the natural history after anterior cruciate ligament disruption.