Out of the non-nephroblastoma population, both cases of ccRCC analyzed (mean age 11 years) showed weak-to-moderate (<50% of cells) diffuse cytoplasmic WT1 positivity, as well as strong (>50% of cells) cytoplasmic WT1 positivity for the one case of rhabdomyosarcoma (2-year-old), and moderate cytoplasmic WT1 staining for the one case of malignant rhabdoid tumor (2-year-old) [65]. This evidence concerns the gene WT1 and Nephroblastoma.