EWSR1 and Ewing sarcoma: Ewing sarcoma is a bone and soft tissue tumor characterized by morphologically small round blue cells and a molecular fusion gene between an RNA-binding protein FET family member (EWSR1, FUS, TAF15, etc.)and an ETS family transcription factor, most commonly EWSR1–FLI1 resulting from chromosomal translocation t(11;22)(q24;q12), present in around 85% of Ewing sarcomas [6].