PAX3 and neoplasm: The clinical and molecular characteristics of RMS tumours, highlighting the cell morphology—similar to that of rhabdomyoblasts—the tumour location—generally in striated muscle, and the expression of various myogenic factors (among others PAX3/7, myogenin and MyoD), have favoured the association of RMS development with a disruption in the proliferation and differentiation of myogenic progenitors [4].