Histologic variants of urothelial carcinoma: differential diagnosis and clinical implications.

An increasing number of histologic variants of urothelial carcinoma have been recognized in recent years. It is important for surgical pathologists to be aware of these morphological variants that, on occasion, may lead to misinterpretation as benign. Some also require a specific therapeutic approach. In this article, we review the most common histologic variants of urothelial carcinoma of the bladder. Emphasis is placed on clinical significance and differential diagnosis.