Atypical Ewing sarcoma breakpoint region 1 fluorescence <i>in‐situ</i> hybridization signal patterns in bone and soft tissue tumours: diagnostic experience with 135 cases

While our study confirmed that FISH is a sensitive and specific tool in the diagnosis of EWSR1-associated tumours, atypical FISH signals and classical rearrangement in entities other than EWSR1-associated tumours can occur. Therefore, it is essential that the FISH result not be used as an isolated test, but must be evaluated in the context of clinical features, imaging, pathological and immunohistochemical findings.