MYOD1-Mutant Spindle Cell/Sclerosing Rhabdomyosarcoma

**Semantic type:** Neoplastic Process

**Definition:** Spindle cell/sclerosing rhabdomyosarcoma characterized by the presence of MYOD1 p.Leu122Arg substitution mutation. This subtype includes most spindle cell/sclerosing rhabdomyosarcomas in adolescents and young adults, as well as some cases in older adults. It follows an aggressive clinical course.