MOLECULAR VARIANTS OF THE EWS-WT1 GENE FUSION IN DESMOPLASTIC SMALL ROUND-CELL TUMOR

We report two cases of desmoplastic small round cell tumor (DSRCT) wit h novel molecular variants of the specific EWS-WT1 gene fusion. This f usion usually encodes a chimeric RNA with an in-frame junction of exon 7 of EWS to exon 8 of WT1. In one variant patient, the EWS-WT1 fusion transcript contained an in-frame junction of exon 9 of EWS to exon 8 of WT1. Moreover, in this patient the tumor arose in the hand, an extr emely unusual site for DSRCT, In the second patient, an in-frame junct ion of exon 10 of EWS to exon 8 of WT1 was present. These two cases of DSRCT shaw that the molecular variability in the EWS breakpoint obser ved in the EWS-FL11 fusion of Ewing's sarcoma can occur in DSRCT as we ll. This type of heterogeneity is relevant to the interpretation of mo lecular diagnostic assays and could also affect the functional propert ies of the encoded chimeric transcription factors.