Localization of the neuronal class III beta-tubulin isotype in foci of early neuritogenesis supports divergent neuroblastic differentiation potential in Wilms' tumors.

Wilms' tumors are embryonic neoplasms that have been proposed to originate from the metanephric blastema and are capable of divergent epithelial and mesenchymal differentiation. Neuroepithelial differentiation in these tumors remains controversial. The aim of this study was to examine the phenotypic profile of certain neuronal and glial antigenic determinants in a series of 21 Wilms' tumors. Immunohistochemical studies were performed by using monoclonal antibodies against the neuronal class III beta-tubulin isotype (beta III), the phosphorylated and phosphorylation-independent epitopes of neurofilament protein, and synaptophysin; antisera to gamma-enolase (neuron-specific enolase) glial fibrillary acidic protein, and S100 protein were also used. Foci of neoplastic cells with neurite-like processes that exhibited intense beta III staining were demonstrated in blastemalike areas of three of 21 tumors. In one case, Homer Wright rosettes (stained for beta III) were identified. Areas of abortive neuritic development were also labeled with antibodies to gamma-enolase. No reactivity was obtained in these foci for phosphorylated and phosphorylation-independent epitopes of neurofilament protein, synaptophysin, glial fibrillary acidic protein, and S100 protein. The remainder of the tumors (18 of 21) were negative with the panel of neural markers. Our results indicate that divergent neuroblastic differentiation, evidenced as early neoplastic neuritogenesis, may be present in the blastematous component of Wilms' tumor subsets.