Subsequent molecular analysis showed the presence of an EWSR1-WT1 gene fusion by fluorescence in situ hybridization, which was confirmed by reverse- transcriptase polymerase chain reaction.     ///    "To our knowledge, this is the first case reported with EWSR1-WT1 fusion in a small round blue cell tumor with smooth muscle differentiation and an indolent course.. "    ///    Low-grade small round cell tumor of the cauda equina with EWSR1-WT1 fusion and indolent clinical course.. 