Ewing sarcoma can develop in any part of the body. Clinically, the most common areas where pain typically begins are the legs, pelvis, and chest wall. Specifically, the areas around the growth plates of the femur (thigh bone) are among the most frequently affected sites, followed by the tibia (shin bone) and humerus (upper arm bone). Persistent, severe pain in these areas, occurring both day and night without relief, should raise suspicion for Ewing sarcoma.