Evaluation of polysialic acid in the diagnosis of Wilms' tumor. A comparative study on urinary tract tumors and non-neuroendocrine tumors.

The polysialic acid moiety of the neural cell adhesion molecule has been shown to represent an onco-developmental antigen which can be detected in both embryonic human kidney and Wilms' tumor but not in normal adult human kidney. In the present comparative study, Wilms' tumors, clear cell (bone-metastasizing) sarcomas of kidney, cystic nephromas, renal cell carcinomas, transitional cell carcinomas and papillomas of the renal pelvis, ureter and urinary bladder (as well normal transitional epithelium from these regions). Ewing sarcomas, hepatoblastomas, rhabdomyosarcomas, and carcinomas of the stomach, colon, exocrine pancreas, lung, and esophagus, were investigated immunohistochemically for the presence of polysialic acid. In addition, immunoblot analysis was performed in selected tumors. With the exception of Wilms' tumor, none of the tumors investigated was positive for polysialic acid. In Wilms' tumor, blastemal cells and all epithelial components were positive but no immunostaining was observed in the stroma. These observations emphasize the potential value of a monoclonal anti-polysialic acid antibody in identifying blastemal metanephric cells and their epithelial differentiatives in Wilms' tumor.