The consistent use of the 2004 World Health Organization (WHO) classification of non-invasive urothelial papillary tumors should result in the uniform diagnosis of tumors diagnosis, stratified according to risk potential, and will facilitate comparative clinical studies, the incorporation of molecular data and the identification of aggressive, genetically unstable neoplasms. Until the 2004 WHO system is fully validated from the clinically and prognostically, point of view, tumors should be graded according to both the 2004 WHO scheme and the 1973 WHO system.
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