Intraepithelial lesions of the urinary bladder with a discussion of the histogenesis of urothelial neoplasia.

Bladder neoplasia of the transitional cell type progresses by two distinct, but occasionally interrelated, pathways characterized morphologically by a papillary or nonpapillary configuration. In this review, the authors discuss intraepithelial lesions of the urinary bladder, le, those lesions confined within the basement membrane of the urothelium. The emphasis is on histogenesis of bladder neoplasia, its putative precursor lesions, and its noninvasive forms. Areas of controversies are highlighted, and the pertinent clinical features, histological findings, and biological potential of these lesions examined.