The prototypical SMARCB1-deficient cancer is MRT, but numerous other tumor types with the complete loss of SMARCB1 have been described such as renal medullary carcinoma (RMC), epithelioid sarcoma (ES), and pediatric poorly differentiated chordoma, almost all of which have a poor prognosis [11,14,15,16,17]. The gene discussed is SMARCB1; the disease is epithelioid sarcoma.