We report a case of urothelial carcinoma in situ extended to the whole excreto-urinary tract and involving the prostatic gland and the papillary ducts of the kidney. The patient was followed up for almost five years. The evolution was unfavorable, as multifocal invasion appeared. We emphasize the difficulties of the pathological diagnosis on biopsy samples and relate the usual behaviour of this type of cancer who may often simulate an interstitial cystitis. Because of uncertain prognosis and difficulties in the evaluation of the disease, the optimal management for such patients remains imprecise in spite of the benefit of cytologic surveillance. Thus, in the absence of obvious invasion the choice of treatment depends at time on morphological data as well as on topographic and functional criteria.