Recent studies have identified a subgroup of undifferentiated soft tissue sarcomas with primitive round to plump spindle cell morphology and a t(4;19)(q35;q13.1) translocation resulting in the expression of a CIC-DUX4 fusion transcript, including 2 tumors previously reported by our laboratory (Cancer Genet Cytogenet 2009;195:1).     ///    The CIC-DUX4 fusion transcript is present in a subgroup of pediatric primitive round cell sarcomas..     ///    "In the present study, reverse transcriptase polymerase chain reaction assays developed for both frozen and paraffin-based tissues were applied to a series of 19 pediatric undifferentiated soft tissue sarcomas using a combination of primer sets covering the CIC-DUX4 fusion transcript. "    ///    Three of the 16 undifferentiated soft tissue sarcomas with primitive round cell morphology were found to harbor the CIC-DUX4 fusion transcript by reverse transcriptase polymerase chain reaction.     ///    "Given the consistent involvement of the CIC-DUX4 fusion in a subset of primitive round cell undifferentiated soft tissue sarcomas, these findings suggest a central role for the fusion transcript in such tumors. "