Conclusion and Results (Outcome and follow-up):
Our patient started Denosumab therapy, by which the size of the acetabular/iliac expansile mass lesion remains stable and the after 7 months of therapy, the follow-up PET/CT shows a significant reduction of the SUV max from 12 to 6.7. Clinically, the patient reported reduced pain with good clinical response. Hence, he continued Denosumab for another six months, anticipating potential surgery. One year after therapy, the patient only experienced pain upon bending, long walks, and running. MRI showed stable lesion size with slight internal changes. A recent PET/CT scan demonstrated a stable lytic lesion with mild improvement. Currently, the patient resumed his job and reported no pain or other complaints. He continued Denosumab therapy with regular follow-ups.