The KMT2A (MLL)-MLLT1 gene rearrangement was confirmed by multiplex reverse transcriptase polymerase chain reaction.     ///    "KMT2A (MLL) rearrangements are observed in various types of pediatric and adult leukemia, but only one adult case report has so far showed KMT2A (MLL)-MLLT1 gene rearrangements in BPDCN. "    ///    We suggest that the pathogenesis of BPDCN could be associated with KMT2A (MLL) rearrangement (especially with KMT2A (MLL)-MLLT1) and further study on a larger number of cases is needed.     ///    We present the first pediatric case of BPDCN with a KMT2A (MLL)-MLLT1 rearrangement confirmed by molecular study.     ///    KMT2A (MLL)-MLLT1 rearrangement in blastic plasmacytoid dendritic cell neoplasm.. 