The Paris System
The Paris System for Reporting Urinary Cytology (TPS) has been developed by international group of members of the American Society of Cytopathology and the International Academy of Cytology to emphasize the goal of detecting High Grade Urothelial Carcinoma (HGUC) while minimizing the emphasis on Low Grade Urothelial Neoplasms (LGUN). Consequently, definition of the characteristics of the intermediate category of atypia aims at decreasing that category into a clinically meaningful one. Criteria for each category have been based on the best available clinical outcomes evidence. The uniqueness of the Paris System for Reporting Urinary Cytology lies in the fact that the system is based on understanding of the pathogenesis of urothelial carcinoma and recognizing two separate pathogenetic pathways; one leading to the development of a low grade urothelial neoplasm and the other leading to the formation of a high grade urothelial carcinoma, which is clinically significant and should be detected by cytology. From its inception, the system became enthusiastically accepted by cytology practitioners who recognized the significance of this more simplistic, but clinically significant, approach to urine cytology. It appears that urine cytology is no longer one of the most frustrating and difficult areas of cytology.
