Myogenin is highly expressed in ARMS, but it is not a completely reliable marker in the differential diagnosis between ARMS and ERMS, since its expression is highly variable in ERMS; conversely AP2β (TFAP2) has been found to be selectively expressed in t+ ARMS and might represent a helpful tool in the morphologic diagnosis. This evidence concerns the gene TFAP2B and alveolar rhabdomyosarcoma.