Immunohistochemically, the tumor cells were positive for desmin (monoclonal, D33), MYOD1 (multifocal staining) (monoclonal, 5.8A); focally expressed smooth muscle actin (SMA) (monoclonal, 1A4) and myogenin (monoclonal, L026), while negative for S100 protein, SOX10, heavy isoform of caldesmon (H caldesmon) (monoclonal, h-CD) and ALK (monoclonal, D5F3). The gene discussed is MYOG; the disease is neoplasm.