Biphenotypic sarcoma with characteristics of both a Ewing sarcoma and a desmoplastic small round cell tumor

Background. The EWS gene, a transcription factor of unknown function, is in volved in chromosomal translocations associated with a wide variety of tumo rs, particularly small round blue cell tumors such as Ewing sarcoma, it has previously been reported that desmoplastic small round blue cell tumor (DS RBCT) frequently has an associated t(11;22) abnormality resulting from fusi on of the EWS and WT-T genes. Procedure. We report a case of a small round blue cell tumor with characteristics of both Ewing sarcoma and DSRBCT with a t(11;22) translocation leading to fusion of the EWS and FLI1 genes. Resul ts. The translocation point and fusion products were confirmed by polymeras e chain reaction amplification and restriction fragment mapping of the prod ucts. Conclusions. The biphenotypic nature of this case and the apparent pr omiscuity of the EWS gene in tumor-associated translocations coupled with o ther reports of biphenotypic childhood sarcomas has potential implications for the relationship between small round blue cell tumors and the mechanism of EWS/FLI1 oncogenesis. (C) 2000 Wiley-Liss, Inc.