What is atypia? Use, misuse and overuse of the term atypia in diagnostic cytopathology

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.

Leveraging thoughtful quality metric selection for individual and system improvements: the atypical category and use of dashboards

Quality management is integral to the practice of cytopathology, especially given the heavily manual workflows and expanding ancillary testing requirements inherent to the cytopathology laboratory. Monitoring quality data like turnaround time, specimen unsatisfactory rates, and diagnostic category utilization rates allows for better understanding of performance with opportunities for targeted improvement if there are variations from that which is expected. However, there are costs to quality monitoring including the time and resources needed, and, in already taxed systems, quality management risks being viewed as just another box to check. While there are mandated quality metrics that must be collected by cytology laboratories, thoughtful selection of key performance indicators can be of tremendous benefit in helping to better understand complex laboratory processes and directing improvement endeavors where needed. The following short communication is a discussion on quality management in the cytopathology laboratory from 3 Cytopathology Quality Management Directors. The discussion focuses on monitoring the atypical reporting category with an emphasis on how trending and visualizing quality metrics can provide laboratories with key data.

A comparative study of diagnostic accuracy in 3026 pleural biopsies and matched pleural effusion cytology with clinical correlation

BACKGROUND

Pleural effusion can be caused by a wide range of benign and malignant conditions. Pleural biopsy and effusion cytology represent two key methods of pathological diagnosis. To compare the performance these two methods, a large cohort of matched pleural biopsy and effusion cytology with clinical follow-up was reviewed.

METHODS

Pleural biopsies and effusion cytology specimens over a period of 18 years were retrieved. Cytology specimens collected within 7 days of pleural biopsy were matched. Reports were reviewed, and the cause for pleural effusion was determined by hospital disease coding and clinical data.

RESULTS

Totally, 3026 cases were included. The leading cause of benign effusion was tuberculosis (n = 650). Malignant pleural effusion (MPE) was more common in older females (p < 0.001) and mostly due to lung cancer (n = 959), breast cancer (n = 64), and mesothelioma (n = 48). The inadequate/insufficient (B1/C1) rate of biopsy was higher than cytology (15.6% vs. 0.3%) but the rates for other diagnostic categories were similar. Biopsy and cytology showed a correlation coefficient of 0.315, improving to 0.449 when inadequate/insufficient (B1/C1) cases were excluded. The ROM for benign cytology (C2) was lower than biopsy (B2) (p < 0.001). Compared with biopsy, the diagnostic accuracy was higher in cytology overall and for metastatic carcinomas (p < 0.001) but lower for hematolymphoid malignancies (p = 0.014) and mesotheliomas (p = 0.002).

CONCLUSIONS

These results suggest that effusion cytology may be better for confirming benignity and diagnosing carcinomatous MPE. In these cases, pleural biopsy may be withheld to reduce procedural risks. However, for suspected hematolymphoid malignancies and mesothelioma, biopsy should be considered.

The cytologic diagnosis of "atypical": Criteria and controversies

Historically, the word "atypia" has been applied as a descriptor for cytomorphologic changes that deviate from what is expected; the assessment of deviant vs. expected cytomorphology is in the eye of the beholder. "Atypia" has been used to define a spectrum of changes which includes reactive changes known to be benign, but also for those concerning for malignancy, as well as everything in-between. The absence of a standardized reporting system and/or the lack of communication with clinicians can lead to the overutilization of the atypical category. When faced with a high rate of atypical diagnoses, clinicians are unable to distinguish patients who need more aggressive follow up from those that do not. Patients accessing their test results may not understand what an "atypical" diagnosis means; this can lead to unnecessary patient anxiety. Finally, atypical diagnoses can trigger reflex ancillary testing. This impacts ancillary test performance, as performance depends upon the pre-test probability of the cohort being tested. The inappropriate testing of low-risk patients can result in an increased number of false positive tests, which in turn lead to unnecessary procedures. Given these challenges, we present this special issue on "atypical" diagnoses in the field of cytopathology. In this issue, experts in various areas of cytopathology review the literature and discuss the diagnostic dilemmas of rendering "atypical" cytologic diagnosis, associated controversies, the effect on patient management, and abuse of ancillary studies. This issue also includes brief commentaries from clinicians from four different medical specialties who often encounter indeterminate cytologic diagnoses.

All in for patient safety: a team approach to quality improvement in our laboratories

Patient safety and quality improvement initiatives are integral parts of every cytopathology laboratory. The need to revisit our approaches to patient safety are essential in light of the expanding test menu, ancillary studies, comprehensive diagnostic reports, and emergence of new technologies for augmenting cytologic diagnosis. Our interview with Drs. Yael Heher, Adam Seegmiller, and Paul VanderLaan explores recent developments that have shaped their perspectives in patient safety, test usage, and laboratory quality. The practical strategies presented provide tools for enhanced patient safety and improved outcomes in a new era of ancillary and molecular testing and standardized reporting in the cytopathology laboratory.

Cytologic diagnosis of "atypical" in serous fluid cytopathology. Approach of the international system for reporting serous fluid cytopathology

Diagnostic uncertainty may occur with almost any entity on cytological evaluation, depending on the quality and quantity of the provided sample. In serous fluid cytopathology, until recently, there had been no defined or agreed criteria for atypia and suspicious categories. Historically, the two descriptive terms appear to have been used almost interchangeably. The international system for serous fluid cytopathology is the first attempt by an expert international authorship to suggest the scenarios in which these terms are used and propose some diagnostic criteria and clinical management strategies.

Significance of hepatocyte atypia in liver fine needle aspiration

Fine needle aspiration (FNA) of the liver is frequently the diagnostic procedure of choice for sampling hepatic lesions. One of the main diagnostic challenges in the interpretation of liver FNA is distinguishing dysplastic lesions and well-differentiated hepatocellular carcinoma (WD-HCC) from benign processes, as they share significant cytomorphologic overlap. Furthermore, the diagnosis of HCC often requires evaluation of stroma for invasion, which may not be present on cytology and small needle biopsy specimens. A reporting system for liver cytopathology has yet to be instituted. Without standardized and well-defined criteria for hepatocyte atypia, we recommend limiting the use of atypia in evaluation of liver FNA specimens to describe a diagnosis of exclusion, in which all known benign and neoplastic processes have been ruled out. The cytologic findings on the FNA of a liver nodule may be best reported as atypical hepatocytes in the absence of a core needle biopsy or cell block sufficient to render a definitive diagnosis of HCC.

Clinician's commentary: Atypia in urinary tract cytology specimens

At the 18th International Congress of Cytology in Paris in 2013, the "Paris Group" created standardized reporting system/criteria for urine cytopathology. This reporting system provided evidence-based criteria for all the urine cytopathologic diagnosis in aims to avoid atypia being used a "waste basket." The addition of standard classification system greatly helps minimizing atypia diagnosis; however, clinicians, specifically, urologist, are still left without a clear set of guidelines for how to approach atypia. Prospective collaborate work with cytopathologists and urologist can help solve the dreaded atypia cytology pathological report and provide a framework and guidelines on management, providing better care to our patients.

Comparison of conventional and liquid-based cytology using The Paris System for Reporting Urinary Cytology

BACKGROUND

This retrospective study was conducted to compare the conventional cytospin method and ThinPrep liquid-based urinary cytology in diagnosing bladder cancer using The Paris System (TPS) of classification.

METHODS

We retrieved files for 2020, at the Cytopathology Department of Laiko Hospital, of urinary cases diagnosed according to TPS. Cytospin and ThinPrep slides were separately reviewed and new diagnoses were rendered, then compared with the original diagnosis and histology when available. Risk of high-grade malignancy (ROHM) for each TPS category was assessed, along with accuracy parameters of each method and their combination.

RESULTS

The study material comprised 100 cases of void urinary cytology classified as 20 high-grade urothelial carcinoma (HGUC = TPS5) cases, 20 of suspicion for HGUC (SHGUC = TPS4), 25 of atypical urothelial cells (AUC = TPS3), and 35 of negative for HGUC (NHGUC = TPS2). A single inadequate (TPS1) case and 4 of low-grade urothelial neoplasm (TPS6) were excluded as small in number. The ROHM was 95% for HGUC, 55% for SHGUC, 28% for AUC and 5.7% for NHGUC. Agreement with the original diagnosis was 86% for cytospin and 82% for ThinPrep. No significant differences were observed among the two techniques or their combination regarding sensitivity and specificity, with a mild advantage for cytospin. Interobserver reproducibility and repeatability were high.

CONCLUSION

No significant differences were found concerning sensitivity and specificity between cytospin and ThinPrep when applying TPS criteria. TPS is a reliable classification scheme for either conventional/cytospin or liquid-based cytology, or their combination.

Evaluation of pelvic washing specimens in patients with endometrial cancer: Cytomorphological features, diagnostic agreement, and pathologist experience

BACKGROUND

Pelvic washings for patients with endometrial cancer is recommended but not used for staging. The International System for Reporting Serous Fluid Cytology (TIS) has standardized diagnostic categories, but the criteria remain incomplete. The 3 primary goals of this study were to 1) investigate features that distinguish atypical/indeterminate from malignant specimens, 2) measure the level of agreement between chart and reviewer diagnoses, and 3) determine whether the number of years in practice had an effect on the diagnoses rendered.

METHODS

Pelvic washings and surgical pathology specimens for 52 patients with a chart diagnosis of atypical/indeterminate, suspicious, or malignant cytology and 52 age-matched controls with a negative chart diagnosis were included, reviewed blindly by 2 cytopathologists, and assigned a study diagnosis. Morphologic features were assessed. Agreement between original chart diagnoses and reviewer diagnoses were assessed as well as effect of years in practice.

RESULTS

The overall cellularity in cell block (CB) slides for the malignant category was significantly increased compared with the atypical/indeterminate category (P < .0001). In addition, the number of atypical groups in ThinPrep for malignant washings was significantly increased compared with the atypical category (P < .001) and the negative and suspicious categories (P < .0001) in the CB. Overall agreement between the original and adjudicated diagnoses was high (γ = 0.983). There was no significant difference between diagnoses rendered and years in practice.

CONCLUSION

The overall cellularity and number of atypical cells can be used to distinguish between malignant and atypical pelvic washing specimens. There is high reproducibility in the diagnostic categories and high agreement among pathologists, regardless of practice experience. These findings can help refine the criteria for TIS.

Targeted education as a method for reinforcing Paris System criteria and reducing urine cytology atypia rates

INTRODUCTION

The Paris System for Urine Cytology (TPS) provides well-defined diagnostic criteria for the category of atypical urothelial cells (AUC). The current study compares the rate of AUC diagnoses at a large academic medical center before and after an educational intervention (EI) by a urine cytology expert.

MATERIALS AND METHODS

An expert in TPS delivered an educational intervention consisting of an interactive microscope session and a didactic session that focused on the AUC diagnostic category. The number of urine cytology cases, the AUC rate, and the false-negative percentage were calculated before and after the EI, using the electronic medical records and cytologic-histologic correlation records.

RESULTS

A total of 4026 urine cytology cases were signed out in the 25 months prior to the educational intervention and 1585 cases were signed out in the 10 months after the intervention. EI had a significant impact on diagnostic categorization, including a reduction in AUC (19.6% versus 12.5%) and suspicious for high-grade urothelial carcinoma (3.9% versus 3.1%) diagnoses. The cytotechnologists also placed fewer cases into the AUC category during primary screening (27.6% versus 23.0%). Although a higher percentage of cases was reported as negative for high-grade urothelial carcinoma, the false-negative rate did not significantly change after the intervention (1.8% versus 2.0% of negative cases, P = 0.65).

CONCLUSIONS

Focused educational sessions for pathologists and cytotechnologists on the diagnostic criteria for AUC as defined by TPS can significantly reduce the rate of atypical diagnoses without a significant increase in the rate of false negatives.

Experience on the use of The Paris System for Reporting Urinary Cytopathology: review of the published literature

INTRODUCTION

The Paris System for Reporting Urinary Cytology (TPS) was first published in 2016 with clear objectives to standardize cytologic diagnostic criteria and provide uniform reporting, in order to improve patient stratification and associated clinical management. The aim of this paper is to evaluate the performance of TPS and review the literature published since TPS was introduced.

MATERIALS AND METHODS

Original articles focusing on the utilization and performance of TPS in urinary cytology specimens were identified using PubMed for publications from January 2016 to July 2020, using the keywords "Paris System", "urine cytology", and "urinary cytology".

RESULTS

Twenty-three relevant articles in the literature regarding the use of TPS were included in the review from a total of 30,802 urine cytology specimens, of which 21,485 (69.8%) had available diagnoses. Distribution of cases among categories ranged from 50.5% to 95.3% for negative for high-grade urothelial carcinoma (NHGUC), 1.2% to 23% for atypical urothelial cells (AUC), 0.2% to 6.6% for suspicious for high-grade urothelial carcinomas (SHGUC), and 2.2% to 14.1% for high-grade urothelial carcinomas (HGUC). The calculated risk of high-grade malignancy (ROHM) ranged from 8.7% to 36.8% for NHGUC, 12.3% to 60.9%% for AUC, 33.3% to 100% for SHGUC, and 58.8% to 100% for HGUC. Mean ROHM weighted by sample size was calculated at 15.7% (±7.8%), 38.5% (±14.3%), 76.2% (±17.2%), and 88.8% (±12.7%) for NHGUC, AUC, SHGUC, and HGUC, respectively. Reported sensitivity of TPS ranged from 40% to 84.7%, specificity from 73% to 100%, PPV from 62.3% to 100%, and NPV from 46% to 90%.

CONCLUSIONS

The application of TPS in the selected series has improved the screening and surveillance potential of urine cytology, while reducing high rates of indeterminate diagnoses, improving sensitivity and providing proper risk stratification for patients.

Spatial-domain low-coherence quantitative phase microscopy to improve the cytological diagnosis of pancreatic cancer

Use of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) cytology to detect pancreatic cancer is limited, with a high false negative rate mainly due to the relatively fewer number of completely cancerous cells. To improve the accuracy of EUS-FNA cytological diagnosis, we evaluated a novel optical system—spatial-domain low-coherence quantitative phase microscopy (SL-QPM)—to analyze nanoscale nuclear architecture on original cytology samples, especially those diagnosed as indeterminate for malignancy, with the goal of maintaining high specificity and reducing false positive rate. We performed SL-QPM on original cytology samples obtained by EUS-FNA from 40 patients with suspicious pancreatic solid lesions (27 adenocarcinomas, 5 neuroendocrine tumor, 8 chronic pancreatitis), including 13 cases that were cytologically indeterminate. Each diagnosis had been confirmed by follow-up surgical pathology. The SL-QPM-derived nanoscale nuclear architectural parameters distinguished pancreatic cancer from cytologically indeterminate cells. A logistic regression model using nuclear entropy and SD increased the sensitivity of cytology in identifying pancreatic cancer from 72% to 94% while maintaining 100% specificity. The SL-QPM-derived nanoscale nuclear architecture properties show great promise in improving the cytological diagnosis of EUS-FNA for pancreatic cancer and could be used when traditional cytopathology does not get an accurate diagnosis, and can be easily translated into a traditional clinical device.

Variation of cytopathologists' use of the indeterminate diagnostic categories "atypical" and "suspicious for malignancy" in the cytologic diagnosis of solid pancreatic lesions on endoscopic ultrasound-guided fine-needle aspirates

Indeterminate cytologic diagnoses in endoscopic ultrasound guided fine needle aspiration biopsy (EUS-FNA) of solid pancreatic lesions include the diagnostic categories "atypical" (ATY) and "suspicious for malignancy" (SUSP), which are used at variable rates and are associated with variable underlying risk of malignancy. The aim of this study was to determine individual cytopathologists' rates of indeterminate diagnoses in EUS-FNA of solid pancreatic lesions and their relationship to cytopathologists' experience and volume of pancreatic EUS-FNA examined, as well as the potential impact of departmental consensus review on indeterminate diagnoses.

DESIGN

The diagnostic rates of ATY and SUSP and their underlying risk of malignancy were calculated for six cytopathologists who diagnosed 1,114 of 1,225 EUS-FNA of solid pancreatic lesions from 1/1/2001 to 9/15/2014, and were then compared for the periods before and after the implementation of departmental consensus review during 2009.

RESULTS

The six cytopathologists diagnosed 10% of cases as indeterminate; 82 (7.4%) as "atypical" and 29 (2.6%) as "suspicious". The individual cytopathologists' indeterminate diagnosis rates varied twofold (6.67-12.80%) and did not correlate with their experience, total or annual volume of EUS-FNAs. Of the 56/99 (56.57%) cases with follow-up, the underlying rate of malignancy was 47% (35/75; for "atypical" and 87.5% (21/24); for "suspicious"). The underlying rates of malignancy were 33-67% for "atypical" and 80-100% for "suspicious" diagnoses made by individual cytopathologists. The rate of indeterminate diagnoses decreased from 11.55 to 7.88% after the implementation of departmental consensus review.

CONCLUSION

Individual cytopathologists' rates of indeterminate diagnoses and their significance vary; however, consensus review is helpful in reducing these rates. Diagn. Cytopathol. 2017;45:3-13. © 2016 Wiley Periodicals, Inc.