FLI1 and Ewing sarcoma: Nevertheless, the critical issue is that most research on NKX2.2 expression in Ewing sarcoma has mainly been directed toward classic Ewing sarcoma and EWSR1-FLI1 rearrangements. Consequently, a knowledge gap exists in which the diagnostic efficacy of NKX2.2 in other round tumors with blue cell morphology has not been explored [15]. Therefore, we have limited our knowledge about NKX2.2's suitability as a diagnostic marker and rely on some special forms of tumors among these complex tumors [16].