Nephrogenic adenoma: a light and electron microscopic and immunohistochemical study.

Nephrogenic adenoma is a relatively infrequent lesion that involves the bladder, the ureters, and the urethra. Even though several cases have been described since the early 1950s, the etiopathogenesis of the lesion is still uncertain. Electron microscopic and immunohistochemical studies seem to favor a congenital origin.