pT1 urothelial carcinoma of the bladder: criteria for diagnosis, pitfalls, and clinical implications.

One of the challenging areas in genitourinary pathology is the recognition of early invasion in urothelial neoplasia. Not uncommon, the patterns of invasion into lamina propria are subtle because a desmoplastic response is absent. Tangential sectioning due to inability to orient transurethral resection of bladder tumor specimens, crush and cautery artifacts further compound this problem. This review is presented to familiarize surgical pathologists with the criteria and different patterns of lamina propria invasion by urothelial carcinoma. Problems and pitfalls associated with the recognition of invasion and the clinicopathologic significance of lamina propria invasive urothelial cancer are also discussed.