EWSR1 and Ewing sarcoma: Ewing's sarcoma (ES), although rare, is the second most common primary bone malignancy in children and adolescences1, 2 and is characterized by a specific transcript EWS/FLI‐1.3 Standard ES treatment consists of neoadjuvant/induction chemotherapy (neoCT), followed by local treatment (surgery and/or radiotherapy) combined with risk‐adapted consolidation/maintenance chemotherapy.