CD99 and Nephroblastoma: In this regard, the present study confirms that the expression of some immunomarkers can be shared by different SRBCTs: (i) CD99 is expressed by EWS and its T-cell precursor LL; (ii) CD56 is expressed in NB and in the blastemal component of Wilms’ tumor as well as in a minority of cases of alveolar RMS.