This is supported by the fact that cyclin D1 was retained in two cases of EWS which showed both morphological and immunohistochemical artifacts (heterogeneous cellular staining along with non-specific stromal staining with CD99) and in three cases of poorly differentiated NB with absent/focal expression of NB84 (the more sensitive immunomarker for this tumor). This evidence concerns the gene EWSR1 and neuroblastoma.