Application of the international system for reporting serous fluid cytopathology on reporting various body fluids; experience of a tertiary care hospital

Application of algorithmic cytomorphological assessment and immunocytochemistry with the international system for reporting serous fluid cytopathology on pericardial fluid cytology

AIMS

The international system for reporting serous fluid cytopathology (ISRSFC) set forth a five-tiered reporting system with comprehensive validation on pleural and peritoneal fluid cytology. An algorithmic approach for cytomorphological assessment and immunocytochemistry was also described in ISRSFC. Limited data on pericardial fluid are supportive but would benefit from further investigation.

METHODS

Consecutive pericardial fluid cytology over a 4-year period was reviewed by multiple board-certified pathologists according to the ISRSFC. Cytomorphology and immunocytochemistry were assessed sequentially, with respective diagnostic performances computed and compared. Literature review was performed.

RESULTS

In total 358 specimens, including 53 with immunocytochemistry available, were reviewed. There were 137 benign and 221 malignant (MAL) cases. The risks of malignancy were 23.5% non-diagnostic (ND), 29.2% negative for malignancy (NFM), 56.0% atypia of undetermined significance (AUS), 82.6% suspicious for malignancy (SFM) and 99.2% (MAL) for cytomorphological assessment, improving to 23.5% (ND), 29.1% (NFM), 56.8% (AUS), 78.9% (SFM) and 99.3% (MAL) incorporating immunocytochemistry. Ten cases (2.8%) received a change in diagnosis after review of immunocytochemistry. All revisions of diagnostic category were appropriate upgrades/downgrades referenced against clinical information. Cytomorphological typing was accurate for adenocarcinoma (n=81/83, 97.6%), while other carcinomas and lymphomas required immunocytochemistry. Certain subcategories within AUS and SFM pertaining to bland indeterminate epithelial cells or mucinous material were not seen for pericardial fluid.

CONCLUSIONS

The ISRSFC shows robust diagnostic performance for pericardial fluid cytology. For pericardial effusion, disease composition and applicable cytological subcategories differ from its peritoneal and pleural counterparts. Incorporating immunocytochemistry by an algorithmic approach improves diagnostic accuracy. Cytomorphology is accurate for identifying adenocarcinomas, but further typing necessitates immunocytochemistry is necessary.

Diagnostic accuracy of International System for Reporting Serous Fluid Cytopathology: A systematic review and meta-analysis in malignancy diagnosis

This study conducts the first meta-analysis to assess the aggregated risk of malignancy associated with each category of the International System for Reporting Serous Fluid Cytopathology (ISRSFC) for reporting serous effusion cytology, while also evaluating diagnostic accuracy. PubMed/MEDLINE and Embase were systematically searched using the keywords "(pleural, peritoneal, and pericardial effusions) AND (serous effusion cytology) OR (International System for Reporting Serous Fluid Cytopathology)". Articles underwent risk of bias assessment using the QUADAS-2 tool. After excluding inadequate samples, a meta-analysis determined sensitivity and specificity for different cutoff points, including "atypical considered positive," "suspicious of malignancy considered positive," and "malignant considered positive." Summary receiver operating characteristic curves assessed diagnostic accuracy, and the diagnostic odds ratio was pooled. Sixteen retrospective cross-sectional studies, totaling 19,128 cases, were included. Sensitivity and specificity for the "atypical and higher risk categories" considered positive were 77% (95% confidence interval [CI], 68%-84%) and 95% (95% CI, 93%-97%) respectively. For the "suspicious for malignancy and higher risk categories" considered positive, sensitivity and specificity were 57% (95% CI, 49%-65%) and 100% (95% CI, 99%-100%) respectively. Sensitivity and specificity for the "malignant" category considered positive for malignancy were 70% (95% CI, 60%-77%) and 99% (95% CI, 98%-99%), respectively. The pooled area under the curve ranged from 85% to 89.5% for each cutoff. This meta-analysis underscores the ISRSFC's accuracy in reporting serous fluid cytology. It emphasizes the diagnostic importance of the "suspicious" and "malignant" categories in identifying malignancy, and the role of the "benign" category in ruling out malignancy.

Real-World Evidence of Intra-institutional Performance Variation in Indefinite Diagnosis of Pleural Effusion Cytology

CONTEXT.—

Pleural effusion cytology has been widely used in the investigation of pathologic fluid accumulation in pleural spaces. However, up to one-tenth of the cases were not given a definitive diagnosis. These cases have largely been neglected in the bulk of the literature.

OBJECTIVE.—

To provide real-world data on indefinite diagnoses including "atypia of uncertain significance" (AUS) and "suspicious for malignancy" (SFM) in pleural effusion cytology and to investigate pathologists' practice patterns on using these diagnostic categories.

DESIGN.—

We reported the diagnoses of 51 675 cases. Descriptive statistics and correlation coefficients were used to analyze the relationships between different diagnostic categories and pathologists' practice patterns and possible explanatory variables.

RESULTS.—

The diagnoses AUS and SFM were reported in 4060 cases (7.86%) and 1554 cases (3.01%) in the cohort, respectively. The mean rates for these indefinite diagnoses varied up to 3-fold between pathologists. Correlations were found between AUS and SFM, as well as between indefinite diagnoses and negative for malignancy (NFM). No correlations were found between pathologists' years of experience or case volume and the rates of indefinite diagnosis or diagnostic certainty.

CONCLUSIONS.—

A real-world baseline for the rates of indefinite diagnoses in pleural effusion cytology is provided in this large retrospective study. Pathologists show significant variation in their use of indefinite diagnostic categories, and the tendency to use these ambiguous terms was not correlated with individuals' experience or case volume. How to untangle the intertwined relationship between the uncertainty of indefinite diagnoses and that of NFM requires future prospective studies.

Risk of Malignancy in Effusions according to the International System for Serous Fluid Cytopathology: A Review

INTRODUCTION

The International Serous Fluid Cytopathology Reporting System (TIS) was developed to standardize communication among health professionals reporting analyses of serous fluid samples. The categories include non-diagnosis (ND), negative for malignancy (NFM), atypia of undetermined significance (AUS), suspected malignancy (SFM), and malignant (MAL). Each category was characterized by a risk of malignancy (ROM).

METHODS

We performed a literature review to analyze studies related to TIS using several sources, including PubMed, followed by a search of relevant cytopathology journal websites (American Cancer Society, Diagnostic Cytopathology, Journal of the American Society of Cytopathology, and Acta Cytologica and Cytopathology). The search included articles published between January 2020 and December 2023, using the terms "international AND serous fluid system."

RESULTS

We identified 257 articles, of which 20 addressed the inclusion and exclusion criteria. The overall ROMs for each category were 23.55% for ND, 16.46% for NFM, 50.78% for AUS, 91.34% for SFM, and 98.21% for MAL.

CONCLUSION

Considering the TIS-recommended ROM rates, the ND category was between the suggested intervals, while the SFM category rate was bigger than expected. The other categories (NFM, AUS, and MAL) were below expected values. SFM and MAL had a stronger association with MAL results. New studies are needed to determine each category's ROM rate from TIS accurately.

Deciphering Serous Effusions Using the New International System for Reporting Serous Fluid Cytopathology

Introduction Serous effusion cytopathology is a minimally invasive, cost-effective procedure and plays a crucial role in diagnosing a spectrum of pathological conditions, ranging from benign to malignant. The International System for Reporting Serous Fluid Cytopathology (ISRSFC) offers a standardized framework for reporting serous effusions, aiding in better communication and clinical decision-making. Aims and objectives This study aimed to categorize effusions using the ISRSFC reporting system. In addition, we sought to estimate the risk of malignancy (ROM) for each diagnostic category and evaluate the diagnostic performance of conventional smear versus cell block techniques. Materials and methods This cross-sectional study was conducted in the Department of Pathology over one year. We applied the ISRSFC criteria to serous effusions and categorized them accordingly. The ROM for each category was assessed with histopathology serving as the gold standard. Then, the diagnostic performance including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy was evaluated using conventional smear and cell block techniques. Results The study included 185 serous effusion cases, with ages ranging from two months to 85 years. The male-to-female ratio was 1.1:1. Most effusions were pleural fluids constituting about 133 cases (71.9%), followed by peritoneal fluids (47 cases, 25.4%) and pericardial fluids (five cases, 2.7%). Among the fluids, four (2.2%) were diagnosed as non-diagnostic (ND), 152 (82.2%) as negative for malignancy (NFM), four (2.2%) as atypia of undetermined significance (AUS), nine (4.8%) as suspicious for malignancy (SFM), and 16 (8.6%) as malignant (MAL). The overall ROM was 25% for ND, 8.5% for NFM, 50% for AUS, 77% for SFM, and 100% for MAL. The sensitivity, negative predictive value (NPV), and diagnostic accuracy were superior when combining conventional smear with the cell block technique. Conclusions Our findings underscore the use of ISRSFC in categorizing effusion samples, assessing the ROM, and guiding clinical management. Moreover, our study highlights the benefits of employing a combined approach using conventional smears and cell blocks for enhanced diagnostic accuracy in serous effusions.

Comprehensive evaluation of benign and malignant etiologies of different serous effusions with the International System for Reporting Serous Fluid Cytopathology: A multi-institutional study in Taiwan

BACKGROUND

The International System for Reporting Serous Fluid Cytopathology (ISRSFC) was introduced globally in 2019 in response to the absence of a standardized reporting system for serous fluid cytology. This study presents experiences implementing this system across three distinct hospitals in Taiwan.

METHODS

A total of 6177 serous fluid specimens in three hospitals in Taiwan between 2018 and 2020 were retrospectively reviewed and reclassified according to the ISRSFC. Cytohistological correlation and chart review were further performed to investigate etiologies and risks of malignancy (ROMs).

RESULTS

Reclassification showed that 34 (0.7%) of 4838 pleural effusions were nondiagnostic (ND), 4086 (84.5%) were negative for malignancy (NFM), 201 (4.2%) were atypia of undetermined significance (AUS), 92 (1.9%) were suspicious for malignancy (SFM), and 425 (8.8%) were malignant (MAL). The 1231 ascites cases contained 13 (1.1%) ND, 1004 (81.6%) NFM, 53 (4.3%) AUS, 31 (2.5%) SFM, and 130 (10.6%) MAL specimens. In pleural effusions, the ROM was 2.9% for ND, 14.0% for NFM, 52.2% for AUS, 85.9% for SFM, and 95.1% for MAL. In ascites, it was 15.4% for ND, 19.1% for NFM, 52.8% for AUS, 83.9% for SFM, and 92.3% for MAL. In pericardial effusions, it was 0.0% for ND, 11.6% for NFM, 30.8% for AUS, 100.0% for SFM, and 95.2% for MAL. Different effusions' most common benign and malignant etiologies were also disclosed.

CONCLUSIONS

These multi-institutional data have determined the diagnostic usefulness of the ISRSFC, which provides pathologists and physicians with invaluable assistance in correctly classifying effusions for further management.

Review of the impact of the International System for Serous Fluid Cytopathology

The International System for Reporting Serous Fluid Cytology (TIS) has been proposed by an expert working team composed of the International Academy of Cytology and the American Society of Cytopathology, following an international survey. Since its introduction, the TIS has gained worldwide acceptance, and this review aims to assess its global impact. A literature search revealed 25 studies which have presented data on the impact of the TIS. Most of them provide data, including risk of malignancy (ROM) for each diagnostic category, separately for pleural, peritoneal and pericardial effusions, while a few do not separate them. A few studies focus on specific diagnoses like mesothelioma on specific types of fluids or more specific issues like the optimal fluid volume for cytology or interobserver variability. A synopsis of the data from the literature search is presented in four tables. The ROM assessment is discussed, as well as interobserver variability and the use of ancillary diagnostic immunochemistry. In conclusion, our review of the published data suggests that the TIS is a valid classification scheme that has been widely accepted by pathologists globally, is highly reproducible and makes a valuable contribution to clinical therapeutic management.

The Role of Immunohistochemistry in Reducing the "Atypia of Undetermined Significance (AUS)" Category in Serous Fluid Cytology

Background and Aims

The International Serous Fluid Cytopathology Reporting System aimed to establish standardized protocols to ensure consistency in the reporting of serous fluid cytological specimens. In the search for higher diagnostic accuracy and a reduction in indeterminate categories, such as atypia of undetermined significance (AUS), ancillary tests like immunohistochemical (IHC) staining panels were performed. In our study, we aimed to evaluate whether the category of cases diagnosed as AUS by initial examination would change at the end of IHC studies.

Materials and Methods

In total, 375 serous fluid cytology samples were examined in our laboratory for 10 months. Of these, 37 cases that were initially diagnosed as AUS were included in the study. A control group, comprising 20 cases initially diagnosed as negative for malignancy (NFM) was used. For the IHC study, sections from cell blocks were used for each group Then, the slides were stained with Ep-CAM/epithelial specific antigen (MOC31), Hector Battifora mesothelial-1 (HBME-1), and cluster of differentiation 68 (CD68).

Results

Following the IHC study involving MOC31, HBME-1, and CD68, a significant reclassification was observed in cases initially diagnosed as AUS. Specifically, in 86.1% of these cases, a definitive categorization into either NFM or malignant was achieved. Statistical analysis revealed a significant difference between the two groups in terms of achieving a definitive category after the IHC study (P < 0.05).

Conclusion

Our study emphasizes the critical importance of enhancing the initial IHC panel, initially composed of epithelial and mesothelial markers, with CD68. This strategic addition contributed significantly to the reduction of cases categorized as AUS.

The International System for Reporting Serous Fluid Cytopathology-An Updated Review

The International System (TIS) for reporting serous fluid cytopathology was published in December 2020 as a joint project by the International Academy of Cytology and the American Society of Cytopathology. The purpose was to standardize the diagnostic criteria and nomenclature used in reporting serous fluid samples, thereby improving the reproducibility of reports and improving communication between pathologists and clinicians. TIS defines a five-tier system consisting of nondiagnostic, negative for malignancy, atypia of uncertain significance, suspicious for malignancy and malignant categories. This review provides an updated summary of the reporting system, risk of malignancy, potential diagnostic pitfalls, and a practical diagnostic approach to serous fluid specimens.

Application of the International System for Reporting Serous Fluid Cytopathology (ISRSFC) in reporting serous effusion: A retrospective study

In order to develop uniform diagnostic standards and reporting terminology, the International Academy of Cytology and the American Society of Cytopathology have recommended the establishment of the International System for Reporting Serous Fluid Cytopathology (ISRSFC). ISRSFC has 5 diagnostic categories: non-diagnostic (ND), negative for malignancy (NFM), atypia of unknown significance (AUS), suspicious for malignancy (SFM), and malignant (MAL). So far, very few studies have evaluated the risk of malignancy (ROM) and performance characteristics (sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy) of different categories. The purpose of this study was to reclassify serous effusions based on the ISRSFC and to assess their ROM and performance characteristics. All serous effusions from January 2017 to December 2022 were categorized according to the ISRSFC. Using histopathological diagnosis as the gold standard, the ROM and performance characteristics were calculated for each group. Finally, a total of 2103 serous effusion specimens were analyzed. After reclassification, 9 (0.4%) cases were classified as ND, 547 (26%) as NFM, 94 (4.5%) as AUS, 386 (18.4%) as SFM, and 1067 (50.7%) as MAL. The ROMs for ND, NFM, AUS, SFM and MAL were calculated to be 50%, 24.9%, 36.8%, 89.0%, and 100%, respectively. As an easy-to-grasp reporting system, ISRSFC provides a consistent standard for better communication between physicians and pathologists.

Application of international system for reporting serous fluid cytology (ISRSFC) in effusion samples-a prospective study in an oncology setting

INTRODUCTION

Serous fluid cytology is a cost-effective procedure that can help in the diagnosis, staging, and origin of the malignancy. Recently introduced International System for Reporting Serous Fluid Cytology (ISRSFC) standardizes the reporting of serous fluid cytology in the 5 categories: Category 1: Nondiagnostic (ND), Category 2: negative for malignancy (NFM), Category 3: atypia of undetermined significance (AUS), Category 4: suspicious for malignancy (SFM), and Category 5: malignant (MAL). Here, we present our experience adopting the ISRSFC.

MATERIALS AND METHODS

We implemented ISRSFC in December of 2019 at our institute and included a cohort of 555 prospective effusion samples. The pertinent surgical pathology, radiology, and clinical follow-up were also extracted to assess the risk of malignancy (ROM) and performance parameters.

RESULTS

The assessment of interobserver reliability indicated substantial concordance (κ = 0.717) between the 2 investigators for serous fluid categorization. A total of 555 effusion samples were classified as follows: ND, 14 (2.5%); NFM, 394 (71%); AUS, 12 (2.2%); SFM, 13 (2.3%); and MAL, 122 (22%). The ROM for the ND, NFM, AUS, SFM, and MAL categories was 57.1%, 9.9%, 66.7%, 66.7%, and 97.2%, respectively, in peritoneal effusions and 57.1%, 7.1%, 66.7%, 100%, 100%, respectively, in pleural effusions. The ROM for NFM and MAL was 0% and 100%, respectively, in pericardial effusion.

CONCLUSIONS

Application of the proposed ISRSFC can help in achieving uniformity and reproducibility in diagnoses and also help in risk stratification in cytology. ISRSFC was successfully adopted by our cytology laboratory and clinicians, with overall diagnostic performance similar to previous studies.

Effusion cytology of metastatic carcinosarcoma

Objectives

Carcinosarcomas (CSs) are rare gynecological neoplasms seen in elderly females. These are composed of malignant epithelial and mesenchymal components, which appear as adenocarcinoma and high-grade sarcoma. Effusions are encountered uncommonly in CS.

Material and Methods

The study focuses on the cytomorphology of 10 cases of metastatic CS in effusions. In 6 years, there were 10 (0.45%) cases of metastatic CS in effusion samples out of 2240 malignant effusion samples. The samples were processed by SurePath™ and centrifuge technique. Both May-Grünwald-Giemsa and Papanicolaou stained smears were evaluated for cytomorphological features, and the findings were correlated with subsequent histopathology.

Results

The cells were predominantly arranged in ball-like clusters and discretely. The cells had abundant vacuolated cytoplasm and enlarged pleomorphic nuclei. Occasional cases showed scattered spindle cells. The cases were diagnosed as metastatic adenocarcinoma (7/10) and positive for malignant cells (3/10). None of the cases was diagnosed as CS. The primary of these cases was in the uterus (7/10) and ovary (3/10).

Conclusion

The cytological evaluation of such effusion samples rarely demonstrates the classical biphasic pattern of these tumors. Mostly, the carcinomatous component is evident, and the sarcomatous element is inapparent and readily missed.