Flat bladder lesions comprise a spectrum of morphologic changes ranging from reactive atypia to carcinoma in situ (CIS). Differentiating these lesions is important because of differences in patient management and clinical outcome. The precise nature of precursor lesions of bladder cancer remains incompletely understood. Urothelial CIS is the most definitely characterized precursor lesion of high grade bladder cancer. Atypia of unknown significance (AUS) is somewhat controversial. For practical purposes, AUS and reactive urothelial changes should be considered a single entity, since neither lesion has established preneoplastic potential. Simple hyperplasia and papillary hyperplasia are recently identified putative preneoplastic lesions. More recent molecular data also support the precursor nature of intestinal metaplasia and keratinizing squamous metaplasia. In this review, we also discuss the utility of molecular ancillary studies in establishing premalignant lesions, diagnosis, and differential diagnosis of flat bladder lesions.
- Atypia of unknown significance
- Flat lesions
- Molecular pathogenesis
- Urothelial carcinoma in situ
- Urothelial dysplasia
ASJC Scopus subject areas
- Pathology and Forensic Medicine