Dose the bone scan help?
Yes. The femoral lesion has little if any increased activity, whereas the other more typical metastases do.
What is your differential at this stage?
Low grade chondroid lesion, fibrous dysplasia, Paget's disease (unlikely). Metastasis cannot be discounted given the known history, but would be unusual.
CT of the proximal femur demonstrates non-aggressive features, with a narrow zone of transition and slight expansion of the bone. No extra-osseous mass or fracture. Some matrix mineralisation is present.