Preneoplastic Lesions and Conditions of the Urinary Bladder

Abstract

Background and Methods: Early clinical observations regarding the biology of the “at risk” field suggested that sites of urothelial preneoplastic changes could follow several distinct clinical courses. It is possible that areas of dysplasia remain simply dysplastic. Alternatively, the urinary epithelium can progress either to superficial bladder neoplasms, characterized by recurrence but rare life threatening progression, or along the path towards invasion with its well recognised risk of mortality. Evidence in support of these disparate pathways comes from the low progression rate of the majority of superficial bladder tumours, coupled with that fact that many invasive neoplasms present as such initially. Results and Discussion: From the morphological point of view, two basic pathways are identified on the basis of the pattern of growth of the intraepithelial lesions (flat and papillary), the behaviour of these lesions being related to the degree of architectural and cytological alteration of the urothelium. Several classification and grading schemes (including revisions and refinements) of the urothelial non-invasive or intraepithelial lesions have been reported in the literature. However, some controversies on the precise criteria and terminology, especially when the papillary lesions are concerned, are still present.