Urinary cytology and the Paris system for reporting urinary cytology: Implications for urological management

A comparison between conventional and the Paris systems of reporting urinary cytopathology with a literature update

INTRODUCTION

Owing to certain inherent limitations of earlier reporting systems, "The Paris System for Reporting Urinary Cytology (TPS)" was implemented in 2015 to standardize reporting urine cytology with more stringent cytomorphologic criteria. We share our post-TPS experience, comparing it with the conventional system (CS).

AIM

To assess and compare the cyto-histopathologic/cystoscopic agreement between the conventional and the Paris systems (CS and TPS) for reporting urine cytology.

MATERIALS AND METHODS

It is a cross-sectional study involving urine samples from 170 patients divided into two groups (CS and TPS). Of the 170 cases, 85 were reported according to the CS, and 85 were reported according to TPS with all the relevant clinical, radiologic, and cystoscopic findings. Using the kappa statistics, both groups were statistically analyzed for sensitivity, specificity, predictive values, and agreement.

RESULTS

The sensitivity and specificity for high-grade urothelial carcinoma (HGUC) as per TPS were 83.33% and 94.59%, respectively, while they were 73.47% and 80.56% for the conventional system. The agreement for HGUC with TPS was 87.06% with a kappa value of 0.7416, while it was 76.5% with a kappa value of 0.53 for the CS. Implementing the TPS minimized usage of the atypical urothelial cells (AUC) category, increasing the clarity in detecting HGUC.

CONCLUSION

TPS provides better agreement with histopathology than the CS for diagnosing HGUC, which is attributable to stringent TPS criteria that prompt cytopathologists to look more diligently for morphologic and numeric criteria.

Urinary IL-6 and IL-8 as predictive markers in bladder urothelial carcinoma: A pilot study

BACKGROUND

Cytokines are known to be a key a factor in numerous malignancies and to exert an important regulatory role in the tumor microenvironment. Interest has grown in understanding how cytokines modulate the tumor microenvironment and which cytokines may serve as markers of the tumor process; however, a complete picture of the cytokine landscape in bladder cancer remains unclear.

METHODS

Fresh urine specimens with sufficient volume were collected at random intervals. The urine concentrations of IL-8 (CXCL8), CCL18, and CXCL9 were determined using the standard commercially available enzyme immunoassay. The urine concentrations of IL-6 were determined using the high sensitivity enzyme immunoassay kit. Urinary cytokine concentrations were normalized with urinary creatinine concentrations.

RESULTS

Significantly elevated concentrations of IL-6 and IL-8 were detected in the urine from patients with urothelial carcinoma on follow-up compared to patients with benign follow-up. The presence of both IL-6 and IL-8 in the urine samples from the high grade urothelial carcinoma (HGUC) cohort revealed a clear discrimination when compared to samples from patients with benign follow-up. The presence of the combination of both IL-6 and IL-8 had a sensitivity of 90.0% and a specificity of 81.25%. Similar data were obtained when receiver operating characteristic analysis was performed on both IL-6 and IL-8 concentrations in the urine from patients with HGUC vs. the hematuria cohort.

CONCLUSIONS

The presence of IL-6 and IL-8 in urine specimens may have predictive value for urothelial carcinoma. However, a large longitudinal study is required to statistically eliminate confounding factors and support this theory.

Atypical urothelial cells classified according to the Paris System for Reporting Urinary Cytology: A 2-year experience with histological correlation from a Finnish tertiary care center-low rate and high risk of malignancy

BACKGROUND

The Paris System for Reporting Urinary Cytology (TPS) was issued to shift the focus of urine cytology to high-grade lesions to increase the diagnostic accuracy of urine cytology. The aim of this study was to evaluate the power of TPS in the atypical urothelial cells (AUC) category with histological correlation and follow-up.

METHODS

The data cohort consisted of 3741 voided urine samples collected during a 2-year period between January 2017 and December 2018. All samples were prospectively classified using TPS. This study focuses on the subset of 205 samples (5.5%) classified as AUC. All cytological and histological follow-up data were analyzed until 2019, and the time between each sampling was documented.

RESULTS

Of the 205 AUC cases, cytohistological correlation was possible in 97 (47.3%) cases. Of these, 36 (12.7%) were benign in histology, 27 (13.2%) were low-grade urothelial carcinomas, and 34 (16.6%) were high-grade urothelial carcinomas. Overall, the risk of malignancy was 29.8% for all cases in the AUC category, and 62.9% in the histologically confirmed cases. The risk of high-grade malignancy was 16.6% in all the AUC category samples and 35.1% in the histological follow-up group.

CONCLUSIONS

The performance of 5.5% AUC cases is considered good and within the limits proposed by TPS. TPS is widely accepted by cytotechnologists, cytopathologists, and clinicians; it improves communication and patient management.

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

Since the release of The Paris System for Reporting Urinary Cytology (TPS), the assessment of urine cytology specimens has primarily focused on the detection of high-grade urothelial carcinoma (HGUC) and carcinoma in situ (CIS). Fortunately, the malignant cells in these lesions tend to be loosely cohesive, resulting in the natural exfoliation of individual malignant cells into the urine. However, HGUC/CIS lesions occasionally exfoliate larger fragments which can be difficult to assess due to cellular overlap and fragment three-dimensionality. Furthermore, reactive benign urothelial fragments and fragments from low-grade urothelial neoplasms (LGUN) may also be seen in urine specimens and contain atypical cytomorphologic features. As a result, the significance of urothelial tissue fragments (UTFs) is often unclear. Herein, we discuss the literature on UTFs before and after the implementation of TPS, as well as strategies to help overcome this diagnostic challenge.

[How has the Paris System contributed to urine cytology? Evaluating the contribution of the Paris System to urine cytology. A comparative study of the Paris System and the Papanicolaou method in a tertiary centre]

INTRODUCTION AND OBJECTIVES

The Paris System (PS) has replaced the classical Papanicolaou System (PapS) in reporting urine cytology, due to its improved sensitivity and negative predictive value (NPV) without loss of specificity. Furthermore, it has enabled the risk of malignancy to be established in each cytological category. The aim of this study is to compare the Paris System with previous results and determine the changes in sensitivity, specificity, positive predictive value, NPV and risk of malignancy in our centre, MATERIALS AND METHODS: Evaluation of the diagnostic power of urine cytology by means of a retrospective cohort study, comparing two series of 400 cytological studies, one using the Papanicolaou System and the other the Paris System.

RESULTS

In the detection of high-grade urothelial carcinoma, Paris System has better specificity (93.82% PapS vs 98.64% PS; P=.001) and PPV (39.5% PapS vs 70.6% PS; P=.044) than Papanicolaou System, without changes in sensitivity (53.5% PapS vs 37.5% PS; P=.299) or NPV (96.4% PapS vs 94.8% PS; P=.183). The risk of malignancy for the atypical category increases from low to high levels (1.6% PapS vs 40.0% PS; P=.001); the other categories showed no significant statistical changes.

CONCLUSION

The Paris System improves specificity and positive predictive value and establishes a better indication of risk of malignancy for each category, enabling specific clinical management in each case.

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

The Paris System (TPS) for Reporting Urinary Cytology is a standardized, evidence-based reporting system, comprising seven diagnostic categories: nondiagnostic, negative for high-grade urothelial carcinoma (NHGUC), atypical urothelial cells (AUC), suspicious for high-grade urothelial carcinoma (SHGUC), HGUC, low-grade urothelial neoplasm (LGUN), and other malignancies. This study aimed to calculate the pooled risk of high-grade malignancy (ROHM) of each category and demonstrate the diagnostic accuracy of urine cytology reported with TPS. Four databases (PubMed, Embase, Scopus, Web of Science) were searched. Specific inclusion and exclusion criteria were applied, while data were extracted and analyzed both qualitatively and quantitatively. The pooled ROHM was 17.70% for the nondiagnostic category (95% CI, 0.0650; 0.3997), 13.04% for the NHGUC (95% CI, 0.0932; 0.1796), 38.65% for the AUC (95% CI, 0.3042; 0.4759), 12.45% for the LGUN (95% CI, 0.0431; 0.3101), 76.89 for the SHGUC (95% CI, 0.7063; 0.8216), and 91.79% for the HGUC and other malignancies (95% CI, 0.8722; 0.9482). A summary ROC curve was created and the Area Under the Curve (AUC) was 0.849, while the pooled sensitivity was 0.669 (95% CI, 0.589; 0.741) and false-positive rate was 0.101 (95% CI, 0.063; 0.158). In addition, the pooled DOR of the included studies was 21.258 (95% CI, 14.336; 31.522). TPS assigns each sample into a diagnostic category linked with a specific ROHM, guiding clinical management.

Indeterminate atypia in urinary tract cytology: Does it really matter?

The study of atypia in urinary cytology has been ongoing for decades but most studies have focused primarily on test performance in patients with concurrent biopsies and/or limited follow-up periods. While these data are useful, many studies fail to consider patient factors that may alter the pretest probability, which can subsequently affect test performance. An isolated diagnosis of malignancy in urinary cytology usually has a high positive predictive value and allows a urologist to conduct a rigorous workup of the patient to establish a tissue diagnosis. However, it is less certain how an atypical diagnosis impacts patient care, given that many patients have a history of bladder cancer and are already under surveillance with cystoscopy at regular screening intervals. Furthermore, a discrete negative urine cytology is unlikely to allow a patient to forego a cystoscopy procedure due to limitations in the sensitivity of urine cytology. Over the last several years, the introduction of The Paris System for Reporting Urinary Cytology (TPS) has improved the predictive value of atypical diagnoses, but additional studies are needed to evaluate the performance of these diagnoses in specific clinical situations. Such data could better inform urologists on how to manage patients with atypical diagnoses. This review discussed the diagnosis of atypia in urinary cytology and the impact of such a diagnosis in various clinical contexts.

Applicability of the Paris System for veterans: high rates of undiagnosed low-grade urothelial neoplasia

BACKGROUND

The Paris System for Reporting Urinary Cytology (TPS) is a recently developed standardized terminology system. It is well-established that urine cytology has low sensitivity for detecting low-grade urothelial neoplasia (LGUN). Though the majority of tumors are low-grade, surveillance of these lesions is important to monitor for possible progression. Herein, we compared TPS to our veteran integrated system network (VISN) to assess its applicability. We also introduced semi-quantitative scoring to further evaluate cytomorphologic features of high-grade urothelial carcinoma (HGUC).

MATERIALS AND METHODS

Voided and instrumented urine cytology specimens and concurrent biopsies were reviewed from Sept 2018 - Jan 2020. Cytologic diagnoses reported using the VISN institutional system were reevaluated by staff cytopathologists and categorized according to TPS. A semi-quantitative scoring system to evaluate cytomorphologic features was devised.

RESULTS

Cytology and surgical specimens from 105 patients were reviewed. The VISN and TPS reporting systems were compared and showed similar sensitivities and specificities for the detection of HGUC. Rates of biopsy-proven LGUN were high for the negative for high-grade urothelial carcinoma category (NHGUC; 27/53, 50.9%) and atypical urothelial cells (AUC; 14/30; 46.7%) compared to suspicious/positive (0/22, 0%) categories. Major and minor criteria as outlined in TPS were evaluated semi-quantitatively.

CONCLUSIONS

Urine cytology has limited sensitivity for LGUN regardless of the cytologic reporting system used. There was a high rate of LGUN following NHGUC/AUC diagnoses in the Veteran population. Coarse chromatin was determined to be the least sensitive criterion for the detection of high-grade lesions and irregular chromatin rim was most specific.

The Usefulness of 4 Immunoperoxidase Stains Applied to Urinary Cytology Samples in the Pathologic Stage of Urothelial Carcinoma: A Study With Histologic Correlation

BACKGROUND

Currently, the golden rule for the diagnosis of urothelial carcinoma is biopsy and cystoscopy, unfortionally both are costly, invasive, and uncomfortable. While most urothelial cancers are noninvasive at presentation, it is necessary to find a highly sensitive, noninvasive way to diagnose in its earlier stages, Cytology with immunostaining is a noninvasive, reliable method that might play a role in detecting the earlier stages before its progression and accurate correlation with different stages of these tumors.

AIM

This study aimed to reach an accurate level in the staging of urothelial carcinoma using CD44, ProExC, Laminin, and Fascin on urinary cytology.

DESIGN

We include a total of 180 urinary cytology specimens with their surgical biopsies' counterparts, the staging of the surgical specimens were done according to AJCC2017TNM classification, while their counterpart urinary samples were centrifuged and the sediment was used for H&E and immunocytochemical staining with CD44, ProExC, Laminin, and Fascin.

RESULTS

The diagnosis of Ta-stage tumors was done according to the following immunohistochemical (IHC) profile [positive (+ve) CD44, negative (-ve) proExC, -ve Laminin, and -ve Fascin] with 100% sensitivity, 100% specificity. The diagnosis of Tis stage tumors was done according to IHC profile [-ve CD44, +ve proExC, -ve Laminin, and -ve Fascin] with 100% sensitivity, 93% specificity. The diagnosis of T1 stage tumors according to IHC profile [-ve CD44, +ve proExC, +ve Laminin, and -ve Fascin] with 100% sensitivity, 97% specificity, The diagnosis of T2 and T3 stage tumors was done according to IHC profile [-ve CD44, +ve proExC, +ve Laminin and weak to moderate +ve Fascin] with 100% sensitivity, 92% specificity, while the diagnosis of T4 stage tumors according to the IHC profile [-ve CD44, +ve proExC, +ve Laminin, and intense +ve Fascin] with 100% sensitivity, 100% specificity.

CONCLUSION

Using (CD44, ProExC, Laminin, and Fascin) on urinary cytology is a simple, reliable, and noninvasive method for the staging of urothelial carcinoma with 99% total accuracy.

Significant reduction of indeterminate (atypical) diagnosis after implementation of The Paris System for Reporting Urinary Cytology: A single-institution study of more than 27,000 cases

BACKGROUND

Urinary cytology is a noninvasive and cost-effective diagnostic and surveillance test in the clinical management of urothelial carcinoma (UC). The Paris System for Reporting Urinary Cytology (TPS), published in 2016, introduced definite diagnostic criteria aimed at improving performance in detecting high-grade UC (HGUC) and decreasing the indeterminate (atypical) diagnosis.

METHODS

The authors retrospectively reviewed and compared urinary cytology diagnoses reported between January 2013 and December 2014 (pre-TPS, 7658 cases) and between May 2016 and April 2018 (post-TPS, 20,026 cases) to assess the influence of TPS in their practice. The time in between was used as a learning period. Follow-up information and correlation with the UroVysion fluorescence in situ hybridization test were obtained when available.

RESULTS

Urinary cytology diagnoses pre-TPS included negative for UC (NUC) (n = 5293; 69.2%), atypical urothelial cells (AUC) (n = 2227; 29%), and suspicious/positive for HGUC (SHGUC/HGUC) (n = 138; 1.8%). Diagnoses post-TPS included negative for HGUC (NHGUC) (n = 18,507; 92.4%), AUC (n = 1237; 6.2%), and SHGUC/HGUC (n = 282; 1.4%). Comparing the pre-TPS and post-TPS periods, AUC diagnoses decreased from 29% to 6.2% (P < .00001), and the specificity and positive predictive value of AUC to detect HGUC significantly improved from 49% to 86% (P < .00001) and from 9% to 39% (P = .002), respectively. The correlation of an AUC diagnosis with a positive UroVysion test improved from 17% to 38% (P < .00001), whereas overall use of the UroVysion test was decreased.

CONCLUSIONS

Implementation of TPS resulted in a significant reduction in AUC diagnoses that had a superior correlation with a subsequent biopsy and a UroVysion test, resulting in potential reductions in test use and medical cost.

A review of upper urinary tract cytology performance before and after the implementation of The Paris System

Urinary cytology (UC) is one of the primary diagnostic modalities used for the screening and surveillance of urothelial carcinoma. Despite its widespread use, UC has suffered from a lack of standardized or reproducible criteria and wide interobserver variability, particularly of the designation of atypical urothelial cells. The Paris System for Reporting Urinary Cytology (TPS), published in 2016, aimed to provide a standardized approach for evaluating UC by creating diagnostic categories with specific cytomorphologic criteria. Recent studies have primarily investigated the application of TPS on lower urinary tract specimens and have mostly shown that TPS implementation has improved the performance of UC specimens. Only a few studies have reported the impact of TPS on upper urinary tract (UUT) cytology. Additionally, there is uncertainty as to which cytological features are most predictive of high-grade urothelial carcinoma (HGUC) in the UUT. This review summarizes the literature regarding the utility and performance of UUT cytology and highlights findings before and after the implementation of TPS.

The Paris system of Reporting Urinary Cytology: Strengths and opportunities

The Paris system for reporting urinary cytopathology (TPS) was created to address inherent weaknesses inherent in the practice of urinary cytopathology. While urothelial cytology has always performed well at finding high grade, genetically unstable urothelial carcinoma, it performs poorly when it comes to detecting low-grade urothelial neoplasia. TPS intends to improve the utility of urothelial cytology by focusing on what is important, high-grade urothelial carcinoma. This article is a snapshot of the current state of TPS as it heads into its second edition. Successes are described and further developments are considered.

A review of urinary cytology in the setting of upper tract urothelial carcinoma

Urothelial carcinomas of the upper urinary tract (UUT) are uncommon. Cytological examination of voided urine or washings from the UUT has been part of the standard workup for upper tract urothelial carcinoma (UTUC); however, its value remains controversial. The lack of uniform terminology and specific diagnostic criteria could also have contributed to the inferior performance of urinary cytology for detecting UTUC. The Paris System for Reporting Urinary Cytology (TPS) has provided a standardized reporting system for urinary cytology specimens with clearly defined cytomorphologic diagnostic criteria and found acceptance on an international level after its implementation in 2016. Recent studies have shown that TPS has led to improved diagnostic performance of urinary cytology; however, most of these studies had focused on the evaluation of lower urinary tract cytology specimens. Only a limited number of new research studies have analyzed the effect of TPS when applied to UUT cytology specimens. In the present report, we have summarized the current understanding and utility of UTUC, including its molecular biology, and reviewed the current literature.

Impact of the Paris system for reporting urine cytopathology on predictive values of the equivocal diagnostic categories and interobserver agreement

Background:

The Paris System (TPS) acknowledges the need for more standardized terminology for reporting urine cytopathology results and minimizing the use of equivocal terms. We apply TPS diagnostic terminologies to assess interobserver agreement, compare TPS with the traditional method (TM) of reporting urine cytopathology, and evaluate the rate and positive predictive value (PPV) of each TPS diagnostic category. A survey is conducted at the end of the study.

Materials and Methods:

One hundred urine samples were reviewed independently by six cytopathologists. The diagnosis was rendered according to TPS categories: negative for high-grade urothelial carcinoma (NHGUC), atypical urothelial cells (AUC), low-grade urothelial neoplasm (LGUN), suspicious for high-grade urothelial carcinoma (SHGUC), and high-grade urothelial carcinoma (HGUC). The agreement was assessed using kappa. Disagreements were classified as high and low impacts. Statistical analysis was performed.

Results:

Perfect consensus agreement was 31%, with an overall kappa of 0.362. Kappa by diagnostic category was 0.483, 0.178, 0.258, and 0.520 for NHGUC, AUC, SHGUC, and HGUC, respectively. Both TM and TPS showed 100% specificity and PPV. TPS showed 43% sensitivity (38% by TM) and 70% accuracy (66% by TM). Disagreements with high clinical impact were 27%. Of the 100 cases, 52 were concurrent biopsy-proven HGUC. The detection rate of biopsy-proven HGUC was 43% by TPS (57% by TM). The rate of NHGUC was 54% by TPS versus 26% by TM. AUC rate was 23% by TPS (44% by TM). The PPV of the AUC category by TPS was 61% versus 43% by TM. The survey showed 33% overall satisfaction.

Conclusions:

TPS shows adequate precision for NHGUC and HGUC, with low interobserver agreement for other categories. TPS significantly increased the clinical significance of AUC category. Refinement and widespread application of TPS diagnostic criteria may further improve interobserver agreement and the detection rate of HGUC.

Practice Patterns in Urinary Cytopathology Prior to the Paris System for Reporting Urinary Cytology

CONTEXT.—

The Paris System for Reporting Urinary Cytology has been disseminated since its inception in 2013; however, the daily practice patterns of urinary tract cytopathology are not well known.

OBJECTIVE.—

To assess urinary tract cytopathology practice patterns across a variety of pathology laboratories to aid in the implementation and future update of the Paris System for Reporting Urinary Cytology.

DESIGN.—

A questionnaire was designed to gather information about urinary tract cytopathology practices and mailed in July 2014 to 2116 laboratories participating in the College of American Pathologists interlaboratory comparison program. The participating laboratories' answers were summarized.

RESULTS.—

Of the 879 of 2116 laboratories (41%) that participated, 745 (84.8%) reported processing urinary tract specimens in house. The laboratories reported processing various specimen types: voided urine, 735 of 738 (99.6%); bladder washing/barbotage, 639 of 738 (86.6%); and catheterized urine specimens, 653 of 738 (88.5%). Some laboratories used multiple preparation methods, but the most commonly used preparation techniques for urinary tract specimens were ThinPrep (57.4%) and Cytospin (45.5%). Eighty-eight of 197 laboratories (44.7%) reported preparing a cell block, but with a low frequency. Adequacy criteria were used by 295 of 707 laboratories (41.7%) for voided urine, and 244 of 707 (34.5%) assessed adequacy for bladder washing/barbotage. More than 95% of the laboratories reported the use of general categories: negative, atypical, suspicious, and positive. Polyomavirus was classified as negative in 408 of 642 laboratories (63.6%) and atypical in 189 of 642 (29.4%). One hundred twenty-eight of 708 laboratories (18.1%) performed ancillary testing, and of these, 102 of 122 (83.6%) reported performing UroVysion.

CONCLUSIONS.—

Most laboratories use the ThinPrep method followed by the Cytospin technique; therefore, the criteria published in The Paris System for Reporting Urinary Cytology, based mostly on ThinPrep and SurePath, should be validated for Cytospin, and relevant information should be included in the revised edition of The Paris System for Reporting Urinary Cytology.

A Review of Urine Ancillary Tests in the Era of the Paris System

Aside from its diagnostic importance, urinary tract endoscopy is an uncomfortable, expensive, and time-consuming procedure. Patients with a history of urothelial carcinoma remain at an increased risk for recurrence and the development of de novo disease; most have had exposure to carcinogenic risk factors for decades prior to their first diagnosis that have bathed the entire urothelial tract. Consequently, monitoring these patients over their lifetime has made urothelial carcinoma one of the most expensive cancers for the US healthcare system. This expense has provided a financial incentive for academic and commercial groups to develop a test with a sufficient negative predictive value to reduce the frequency of surveillance procedures. Slide-based tests require a separate slide prepared from a split urine sample or from an additional urinary tract specimen. This process can place an additional burden on the laboratory due to changes in the workflow, especially if the split specimens need to be stored until a cytologic diagnosis is rendered (i.e., when used as a reflex test). Importantly, slide-based tests allow for the result to be directly correlated with cytomorphologic findings; however, these tests require the cells of interest to be present. Thus, slide-based tests suffer from the same sensitivity issues as urinary tract cytology. In contrast, slide-free tests do not require an additional slide to be prepared, and laboratory testing may be centralized to a core facility or performed on-site. Some tests detect the expression of altered or abnormally expressed subcellular material (proteins, DNA, etc.) in urothelial neoplasms, which are found in tumor cells and/or in the urine specimen when the proteins are either excreted or leaked from degenerating tumor cells. Slide-free tests may also be developed into point-of-care tests, meaning that the result may be available to the urologist but not to the cytopathologist. Since these proteins are often disassociated from the tumor cells that produce them, such tests may have a positive result even if tumor cells are absent in the tested specimen. Here we review critical concepts as well as several ancillary tests that have been developed for urinary tract specimens.

Variability among observers utilizing the CellSolutions BestCyte Cell Sorter imaging system for the assessment of urinary tract cytology specimens

INTRODUCTION

Image analysis systems are not currently commonly used for evaluating urinary cytology specimens. We evaluated whether the BestCyte Cell Sorter (CellSolutions, Greensboro, NC) imaging system can reliably identify atypical cells in urinary cytology specimens.

METHODS

Fifty-three consecutive urine cytology specimens underwent 2 preparations: one slide using SurePath (SP; BD Diagnostics, Sparks, MD)^™ for routine clinical evaluation, and a second slide using the CellSolutions F50 system for analysis by the BestCyte Cell Sorter (BCCS) scanning system. Eight observers reviewed atypical cells flagged by BCCS and assigned a BCCS diagnosis to each of the 53 specimens. The observers also blindly reviewed the SP preparation (when available) and assigned an SP diagnosis. The SP diagnoses given by one "expert" observer was considered as a reference diagnosis.

RESULTS

There was fair-to-moderate agreement among observers for identifying any atypia and high-grade atypia (Fleiss kappa: 0.417 and 0.338, respectively) using BCCS. Review of SP preparations had slightly better agreement (Fleiss kappa: 0.558 and 0.564, respectively). Intraobserver agreement between the two methods varied greatly between individuals (Cohen's kappa range: 0.260 to 0.647). When a consensus diagnosis could be reached among the observers for cases with surgical follow-up, the consensus diagnosis was concordant in 11 of 12 instances, with one instance being a one-step discrepancy.

CONCLUSIONS

Specimen review by BCCS resulted in slightly greater interobserver variability than review of routine SP preparations. This may have been due to variations in observer experience and comfort with the use of a digital imaging system, which is further suggested by the wide range of intraobserver agreement among individuals.

The Paris System for Reporting Urinary Cytology: early review of the literature reveals successes and rare shortcomings

The Paris System for Reporting Urinary Cytology (TPS) provides recommendations for the diagnosis of urinary tract cytology (UTC) specimens and has found acceptance on an international level. Since the official release of TPS in 2016, numerous research studies have been published analyzing its impact. This review summarizes the studies published since the release of TPS, highlighting areas in which TPS has performed well and other areas in which TPS may need improvement.