FIGURES AND TABLES LEGEND
Figure1. Histology

1. H&E-stained section showing cells with a mesenchymal appearance set in a loose background stroma, and showing with variable (in this focus, relatively little) skeletal muscle differentiation.
2. Desmin immunohistochemistry, showing diffuse cytoplasmic expression in neoplastic cells
3. Myogenin immunohistochemistry, showing nuclear expression in fewer than 50% of neoplastic cells
4. MyoD1 immunohistochemistry, showing nuclear expression in approximately 50% of neoplastic cells

Table1. Somatic mutation detected by Whole-exome sequencing.
Table2. Frequency of BRAF/RAS mutations co-occurrence