What is the most likely diagnosis taking into account all imaging presented?
Enchondroma.
What is the typical distribution for enchondromas?
Almost all enchondromas are located in the medullary cavity of tubular bones: small tubular bones of the hands and feet (50%); large tubular bones e.g. femur, tibia, humerus.
The lesion in the lateral femoral condyle shows no marrow reaction, has a multilocular appearance and shows typical rim enhancement, with central low signal on all sequences (due to calcification) admixed with high T2 low T1 signal material.
Distal end of femoral intramedullary rod noted.