Background and aims: This paper summarizes the work done by the members of the Committee no. 2 at the International Consultation on the Diagnosis of Non-Invasive Urothelial Neoplasms held in Ancona, Italy (11-12 May 2001). The committee members discussed and reached consensus regarding the optimal contemporary diagnosis and classification of the preneoplastic non-papillary lesions of the urothelium. An important objective was to promote a precise terminology and to use it consistently in daily practice in pathology and urology.
Results and conclusions: The result of the meeting is represented by a refined classification of the non-papillary intraepithelial lesions and conditions of the urothelium. This classification includes epithelial abnormalities (reactive urothelial atypia and flat urothelial hyperplasia), presumed preneoplastic lesions and conditions (keratinizing squamous and glandular metaplasia, and malignancy-associated cellular changes), as well as preneoplastic (dysplasia) and neoplastic non-invasive (carcinoma in situ) lesions. Each of these lesions is defined with strict morphological criteria in order to provide more accurate information to urologists in managing patients.