After further molecular investigation at the Mayo Clinic, USA, the diagnosis of a high-grade SEF was confirmed and the differential diagnoses of previously listed tumours were excluded by molecular methods: fluorescence in situ hybridisation for Ewing's sarcoma (EWS) locus rearrangement and reverse transcriptase, polymerase chain reaction for EWS-Fli-1 and EWS-ERG (Ewing/PNET), SYT-SSX1 and EWS-WTI (for desmoplastic small round cell tumour). The gene discussed is EWSR1; the disease is primitive neuroectodermal tumor.