Pathobiology of Preinvasive Urothelial Neoplasia.

The etiology and pathogenesis of human transitional cell carcinoma (TCC) remain unknown at the present time. While many carcinogens can induce bladder carcinoma in animal experimental studies, the only well-established carcinogens in human beings are tobacco smoke and arylamines.[1] Experimental studies in animals have demonstrated that invasive urothelial carcinoma is preceded by a sequence of progressive intraepithelial changes: generalized thickening of the urothelium or hyperplasia, disordered arrangement of cells with nuclear atypia or dysplasia, and fully developed carcinoma in situ (CIS).[2]