[Notes on the tumorigenesis of bladder urothelioma]

Bladder urothelioma is a common and increasingly frequent tumor, which most of the times involves initially the bladder mucosa only. Urotheliomas can be superficial, with low malignant potential despite their high relapsing activity, and highly aggressive ab initio. A series of events are known to influence urothelioma genesis, growth, cell interactions and apoptosis. Some initial constant changes involving chromosome 9 occur in the urothelium, whereas the 20-30 % of cases also show an alteration on chromosome 20, which is likely to result in marked biological aggressiveness. The transformation of normal urothelium into hyperplastic, and then neoplastic, urothelium is secondary to a wide range of molecular changes, which are here summarized.