Do the imaging findings from the MRI make the primary diagnosis of Ewing sarcoma more or less likely?
The soft tissue mass and lack of osteoid make Ewing sarcoma more likely than osteosarcoma and make it the likely diagnosis in this case.
Multiple intramedullary bone lesions involving both femora and the pelvis bilaterally. Evidence of bilateral acetabular bone involvement with expansion and a soft-tissue component which is more prononced on the right, extending both posterolateral to the bone (into the gluteus musculature) and medially (into the pelvis).
- MRI (T1):
- MRI (T2 fat sat):
- MRI (T1 fat sat):