Effect of the Paris system for reporting urinary cytology with histologic follow‐up

Abstract

Background The Paris system (TPS) for Reporting Urinary Cytology provides a standardized reporting system whose main focus is the diagnosis of high‐grade urothelial carcinoma (HGUC). We conducted a study to see the impact of The Paris System on our cytologic diagnoses with associated histology. Materials and methods We reviewed our pathology database regarding urinary specimens in the year before implementation of The Paris System and the year after. We gathered the data regarding cytologic diagnosis and concurrent/subsequent histology. Results Over a 1‐year period from 2016‐2017, 486 urine cytology specimens were identified before implementation of The Paris System and diagnosed as follows: 83% benign/negative, 10% atypical, 2% suspicious, 5% HGUC, 0.2% low grade urothelial neoplasm (LGUN), and 0.2% unsatisfactory. Over a next 1‐year period from 2017 to 2018, 602 specimens used TPS and diagnosed as follows: 85% negative for HGUC, 6% atypical, 3% suspicious, 4% HGUC, 0.17% LGUN, and 2% unsatisfactory. Although, not listed as a standardized category in The Paris System, our institution used “Negative for high‐grade, cannot rule out low‐grade urothelial neoplasm (NHL)” as a subcategory of Negative for HGUC. 4% of the cases fell into this category. Focusing on the Atypical category before TPS, histology was available in 15/49 (31%) cases. Of these, 40% had HGUC. Regarding the Atypical category after TPS, histology was available in 21/36 (58%) cases. Of these, 52% were HGUC. For the NHL category, concurrent histology was available in 13/26 (50%) cases. Of these, 67% were low grade urothelial neoplasms. Conclusion Our study showed that TPS lowered the rate of Atypical from 10% to 6%. After the implementation of TPS, Atypical corresponded to a higher rate of high‐grade urothelial carcinoma. Also, the NHL subcategory had a high positive predictive value for diagnosing low grade urothelial neoplasms.

Atypical Category of the Johns Hopkins Template Has Higher Risk of Malignancy than the Paris System but the Paris System Is More Applicable for Suspicious Category

“…A study confirmed our result: after the LGUC diagnosis, subsequent cytology resulted in atypical, suspicious, or positive category in 51.9% of cases [32]. Very recently, another study subgrouped LGUC within the NHGUC category [33]. Within this category, concurrent histology was available in 50% of cases.…”

The Paris System for Reporting Urinary Cytology: A Meta-Analysis

“…From its implementation, it has been shown to enhance correlation with histology, especially when the low urinary tract is sampled, while decreasing the indeterminate diagnoses [46,47]. Indeed, a few studies have demonstrated that TPS has reduced the rate of atypical interpretations reported in their departments [48][49][50][51]. This finding has a great clinical significance, as before the implementation of TPS, many urologists were regarding atypical cases as negative [6].…”

“…Nevertheless, TPS focuses on what is more important, which is the detection of HGUC [1,7]. Thus, it has established strict criteria for each one of its categories, including AUC, aiming to identify HGUC rather than LGUN, resulting in a frequency reduction in the "atypical" interpretations compared to the pre-TPS era [48][49][50][51]. Of interest, the pooled ROHM of the AUC reporting category in our meta-analysis was found to be 38.65% (95% CI, 0.3042; 0.4759), which should warrant close clinical follow-up and/or the use of ancillary testing [1,7], rather than being regarded as negative.…”

The Diagnostic Dilemma of Urothelial Tissue Fragments in Urinary Tract Cytology Specimens

“…In the first group, Zare et al [38] reported that 2/52 (4%) LGUN cases were correctly classified post-TPS (vs. 6% pre-TPS); Meilleroux et al found that significantly fewer cases of LGUN were diagnosed post-vs. pre-TPS (0.9% vs. 1.8%), with sensitivities pre-and post-TPS of 31% and 10%, respectively, and specificities pre-and post-TPS of 96% and 100%, respectively [39]. Recently, Rohra et al reported similar rates of LGUN pre-vs. post-TPS (0.2% vs. 0.17%), but also placed 4% of their cases into a separate category of "Negative for high-grade, cannot rule out low-grade urothelial neoplasm", of which on follow-up, 67% were LGUN, 13% HGUC, and 20% negative [40]. The criteria for this category included 3D cellular clusters without fibrovascular cores.…”