What are urothelial proliferation of uncertain malignant potential?

• Replaces papillary and flat hyperplasia. • Two thirds of patients have a history of prior, concurrent, or subsequent urothelial neoplasia. • Has been reported de novo, and in this setting, clinical follow up is suggested. • Early manifestation of a papillary neoplasm. • Clonal, high incidence of ch. 9 deletions+ FGFR3 abnormalities. • The 5-year risk of developing urothelial neoplasia ~40%. • Marked thickening of the urothelium • No or minimal cytological atypia • No true papillary formation.