EWSR1 and primitive neuroectodermal tumor: In clinical diagnostics of FFPE tissue sections, interphase FISH is routinely performed with a commercially available EWSR1 (22q12) dual color, break-apart rearrangement probe, but the t(11;22) is also found in 90% of EWS/primitive neuroectodermal tumor (PNET) and CCS cases (105).