In routine practice, subtyping is achieved via a set of defined phenotypic (such as demonstration of myoid markers in giant cell-rich leiomyosarcoma) [4], genotypic (e.g., presence of H3F3 mutations by molecular testing or using the mutation-specific H3.3 G34W antibody in GCT-B) [6–10] or both features (e.g. demonstration of epithelial phenotype and SMARCB1 inactivation in epithelioid sarcoma) [5]. This evidence concerns the gene SMARCB1 and epithelioid sarcoma.