Morphological and molecular profiles and pathways in bladder neoplasms.

After several decades of use of the Wealth Health Organization (WHO) 1973 grading system for bladder neoplasms (1973 WHO), a new grading system was adopted in 2004 by the WHO (2004 WHO). Some leading experts in the field of urogenital pathology have expressed their concerns with the 2004 WHO categorization system, both with regard to the nomenclature and the grading categories used. Several molecular and genetic studies have provided another perspective on the classification of urothelial neoplasms. The two most important developments are the identification of a mutation in the fibroblast growth factor receptor 3 gene in more than 50% of urothelial carcinomas and the discovery of cDNA profiles characteristic of different subsets of bladder cancer. There is strong correlation between the molecular findings and the 2004 WHO classification and prognosis.