EWSR1 and Ewing sarcoma/peripheral primitive neuroectodermal tumor: Ewing's sarcoma family tumour is a group of small round cell tumors, characterized by the specific translocation t(11;22)(q24;q12) and the specific transcript FLI1/EWS (and by the less common subvariants that involve chromosome 22 and EWS gene, with chromosome 21, 17, or 7).