How do I tell the difference between ewing's sarcoma leg pains, and growing pains?

Where on earth did you hear of many untreated cases because the doctors found nothing on x-ray? I work in pediatric oncology and have not witnessed this at all. Ewings is rare. The pain is intense, and would likely only be in ONE limb. If you're having pain in both femurs, it's so very unlikely to be Ewings.