Morphologists overestimate the nuclear‐to‐cytoplasmic ratio

Abstract

BACKGROUND:The Paris System for Reporting Urinary Cytology (TPS) has defined nuclear-to-cytoplasmic (N:C) ratio cutoff values for several of its risk-stratified diagnostic categories. However, because pathologists are not trained to recognize strict N:C ratio cutoff values, a previously designed survey was used to determine whether pathologists could accurately identify N:C ratios according to TPS standards. METHODS: Participants were instructed to estimate the N:C ratio of ideal (line drawing) and real (cell photograph) images presented via an online survey. Actual N:C ratios ranged from 0.3 to 0.8, and 3 answer choices were available: < 0.5, 0.5 and <0.7, and 0.7. The resulting data were analyzed to determine the accuracy and performance of the subgroups. RESULTS: A total of 137 individuals completed the survey.Approximately 24.1% were cytopathologists, 18.2% were pathologists without formal cytopathology training, 18.2% were cytotechnologists, 24.1% were pathology residents, and 15.3% were nonmorphologists. Overall, 70.0%, 67.6%, and 93.3% of responses, respectively, were correct for images with an N:C ratio of < 0.5, 0.5 and < 0.7, and 0.7. For images with an actual N:C ratio < 0.5 and 0.5 and < 0.7, 30.0% and 25.0% of responses, respectively, overestimated the N:C ratio. Furthermore, for images with an N:C ratio of 0.4 and 0.6, > 40.0% of responses overestimated the N:C ratio. As a whole, morphologists were significantly more accurate than nonmorphologists (P 5.030). CONCLUSIONS: Morphologists tended to overestimate the N:C ratio, particularly at ratios close to TPS-recommended cutoff values. Additional training regarding N:C ratio estimation may help pathologists to adapt to this new system.

Analysis of the Cytomorphological Features in Atypical Urine Specimens following Application of The Paris System for Reporting Urinary Cytology

“…Additionally, cells with elevated N/C ratios can be seen in a variety of conditions including instrumented urine as well as reactive and degenerative changes. Other studies have also suggested poor interrater reliability [9,11] , consistent with our results. The identification of a high N/C ratio along with other features resulted in a higher specificity and was more predictive of malignancy.…”

“…A collection of images was provided to each reviewer detailing the morphological features in question. We utilized photos from TPS [8] and Zhang et al [9] .…”

Accuracy and Reproducibility of Nuclear/Cytoplasmic Ratio Assessments in Urinary Cytology Specimens

“…The nuclear/cytoplasmic (N/C) ratio has been utilized for the diagnosis of carcinoma [1][2][3][4][5][6][7][8] and the grading of carcinomas. [16][17][18] Vaickus and Tambouret 19 demonstrated that trained morphologists were reasonably accurate at estimating N/C ratio, but Zhang et al 20 using similar methods and definitions showed that morphologists overestimated nuclear-to-cytoplasmic ratio. Recently, The Paris System for Reporting Urinary Cytology utilized N/C ratios as important criteria for defining the categories: atypical urothelial cells (AUC), suspicious for high grade urothelial carcinoma (suspicious), and high grade urothelial carcinoma (HGUC).…”

Urinary tract washing specimens containing atypical urothelial tissue fragments are significantly associated with urothelial neoplasia

“…18,19 The large number of specimens included in our study to allow for the required statistical power precluded glass slide review of every specimen. Several studies have shown that pathologists have difficulty determining an accurate nuclear-to-cytoplasmic ratio when analyzing individual cells; accurate assessment in UTF in which cytoplasmic borders are often indistinct may not be possible.…”