Total of 126 patients (Figure 3A–D; higher power images shown in Supplementary Figure S3A–D) comprising 100 embryonal rhabdomyosarcoma and 26 alveolar rhabdomyosarcoma, of which 35 (35%) (Figure 3A–C) and 4 (15%) (Figure 3D), respectively, contained endosialin expression in the tumour cells and 71 (71%) embryonal rhabdomyosarcoma and 12 (46%) alveolar rhabdomyosarcoma showed endosialin expression in stromal fibroblasts. The gene discussed is CD248; the disease is embryonal rhabdomyosarcoma.