PAX7 immunohistochemical evaluation of Ewing sarcoma and other small round cell tumours.

Although we confirmed that PAX7 is a sensitive marker for Ewing sarcoma, anti-PAX7 antibody also stained several Ewing sarcoma mimics, whose spectrum was distinct from NKX2-2-positive non-Ewing entities. Further studies are required to determine how PAX7 could be integrated into practice to classify small round cell tumours efficiently.