Mesenchymal chondrosarcoma diagnosed on FISH for HEY1-NCOA2 fusion gene.    ///    This case suggests that the detection of the HEY1-NCOA2 fusion gene on FISH is of diagnostic value for MC.    ///    This case suggests that the detection of the HEY1-NCOA2 fusion gene on FISH is of diagnostic value for MC.     ///    Mesenchymal chondrosarcoma diagnosed on FISH for HEY1-NCOA2 fusion gene..     ///    "Recently, a tumor-specific HEY1-NCOA2 fusion gene was identified in MC. "    ///    Here we report the case of a 9-year-old boy who was diagnosed with MC by detection of HEY1-NCOA2 fusion signals in almost 50% of tumor cells in tissue sections on fluorescence in situ hybridization (FISH). 