Background: Approximately 10% of nephroblastomas (Wilms' tumors) carry mutations in the Wilms' tumor 1 (WT1) gene. Recently, a WT1 antibody raised against N-terminal 1-181 amino acids of human WT1 became commercially available for immunohistochemical use on paraffin-embedded tissue. The aim of this study was to investigate the diagnostic and prognostic value of WT1 N-terminal antibody in nephroblastomas.
Methods: Twenty-five patients with nephroblastoma were studied. Four clear cell sarcomas of the kidney (CCSK) and 15 neuroblastomas were included for comparative study. WT1 immunostaining was performed on paraffin material using the WT1(6F-H2) antibody. The patients were staged according to the National Wilms' Tumor Study (NWTS) staging system.
Results: Eleven tumors (44%) showed blastemal nuclear staining with or without epithelial nuclear staining. Three of the 13 low-stage tumors (stages I and II) showed WT1 blastemal nuclear staining, while 8 of the 12 high stage (stage III and IV) tumors revealed blastemal nuclear staining. The blastemal nuclear expressions of WT1 were statistically significantly correlated with clinical stage (p = 0.036). All the neuroblastomas and CCSK showed no nuclear immunoreactivity.
Conclusions: The presence of WT1 nuclear immunoreactivity may be helpful to distinguish blastemal predominant nephroblastomas from CCSK and neuroblastomas.