Evaluating the Impact of Sample Volume on Cytological Diagnosis of Pleural Effusion: A Single-Institution Study Using The International System for Reporting Serous Fluid Cytopathology

Introduction: The International Academy of Cytology and the American Society of Cytopathology recently proposed the International System for Reporting Serous Fluid Cytology (ISRSFC) to standardize serous fluid cytopathology reporting and guide further clinical management. The current study aimed to assess the feasibility of utilizing ISRSFC reporting categories for serous fluids, estimate the risk of malignancy (ROM) of each category, and scrutinize if the management protocols followed in our institution are as per the ISRFSFC recommendations. Methods: All pleural, peritoneal, and pericardial effusions submitted for evaluation at our institute between January 2021 and December 2021 were retrieved. All these cases were reviewed and re-categorized into one of the five categories proposed by the ISRSFC: non-diagnostic (ND), negative for malignancy (NFM), atypia of uncertain significance (AUS), suspicious for malignancy (SFM), and malignant (MAL), and ROM was calculated for each category. Results: The present study examined 596 serous effusions, of which 229 were pleural effusions, 358 were peritoneal effusions, and the remaining nine were pericardial effusions. Among 596 cases, 395 cases had a radiological or histological follow-up. The serous effusion samples were re-categorized as 61 (10.2%) ND, 449 (75.3%) NFM, 47 (7.8%) AUS, 17 (2.9%) SFM, and 22 (3.8%) MAL, and ROM for each above category were 10%, 4.4%, 19%, 83.3%, and 100%, respectively. Conclusion: Categorizing serous effusion cytology samples per the ISRSFC diagnostic categories reduces reporting variability. The ISRSFC provides a standardized format to predict the ROM and thus improves the quality of clinical care.

This study investigates the utility of the International System for Reporting Serous Fluid Cytopathology (ISRSFC) in the categorization of pericardial fluid and assesses the diagnostic performance and risk of malignancy (ROM) for each of the diagnostic categories. All pericardial fluid cases at the Yale School of Medicine between January 1, 2017, and December 31, 2020, were reviewed. The diagnoses were reclassified into five categories according to the ISRSFC: nondiagnostic (ND), negative for malignancy (NFM), atypia of uncertain significance (AUS), suspicious for malignancy (SFM), and malignant (MAL). ROM and performance parameters of each category were calculated. After reclassification, the distribution of 465 pericardial fluid cases in each category was as follows: ND, 19 (4.1%); NFM, 332 (71.4%); AUS, 21 (4.5%); SFM, 11 (2.4%); and MAL, 82 (17.6%). Confirmatory follow-ups were available for 16 ND (66.7%), 299 NFM (90%), 15 AUS (71%), 5 SFM (45.5%), and 30 MAL cases (36.6%). The ROM was 0% for ND, 1.3% for NFM (4 of 332), 20% for AUS (3 of 15), and 100% for both SFM (5 of 5) and MAL (27 of 27). The diagnostic performance was as follows: sensitivity, 87% (27 of 31); specificity, 100% (292 of 292); positive predictive value (PPV), 100% (27 of 27); negative predictive value (NPV), 98.6% (292 of 296); and diagnostic accuracy, 98.8% (319 of 323). The ISRSFC is a highly useful system for the reporting of pericardial fluid and risk assessment, given that it offers high sensitivity, specificity, PPV, NPV, and diagnostic accuracy. The application of this system may help to better categorize pericardial fluid and facilitate the standardization of cytopathology reporting.

The International System for Reporting Serous Fluid Cytopathology (ISRSFC) was published recently to provide standard reporting terminology for serous fluid. To date, several ISRSFC reclassification studies have reported a wide range of diagnostic category frequency and the associated risk of malignancy (ROM). Herein, the authors applied the ISRSFC to report pleural and peritoneal effusions retrospectively in a community hospital setting. With Internal Review Board approval, 446 peritoneal effusion specimens and 299 pleural fluid specimens from 576 patients in three community hospitals over a 12-month period were reviewed and reclassified according to the ISRSFC. After reclassification, in pleural effusions, 18 (5.0%) were nondiagnostic (ND), 273 (76.0%) were negative for malignancy (NFM), 18 (5.0%) were atypia of undetermined significance (AUS), 6 (1.7%) were suspicious for malignancy (SFM), and 44 (12.3%) were malignant (MAL). In peritoneal effusions, after reclassification, 11 (5.5%) were ND, 168 (77.1%) were NFM, 9 (4.1%) were AUS, 2 (0.9%) were SFM, and 27 (12.4%) were MAL. The calculated ROM was 0.0% for ND, 1.8% for NFM, 37.5% for AUS, 83.3% for SFM, and 100.0% for MAL in peritoneal effusions; and the ROM was 8.3% for ND, 1.2% for NFM, 44.4% for AUS, and 100.0% for both SFM and MAL in pleural effusions. Further analysis demonstrated notable heterogeneity among published ISRSFC reclassification studies, although the overall ROMs did not differ significantly from the ISRSFC-determined ROMs (all p values were > .05 for mean ROM comparisons). The findings suggested the necessity for each laboratory to perform its own ROM analysis based on its statistics for ISRSFC-tiered classification terminology.

The International System for Reporting Serous Fluid Cytopathology (TIS) classifies serous effusions into five categories: non-diagnostic (ND), negative for malignancy (NFM), atypia of unknown significance (AUS), suspicious for malignancy (SFM) and malignant (MAL). The main objectives of this classification comprise the establishment of a universal code of communication between cytopathologists and clinicians and histopathologists, as well as between different laboratories worldwide, paving the way for the setting of clinical management guidelines based on the risk of malignancy assessment for each diagnostic category. We retrieved the total number of pleural and peritoneal effusion cases of our department for the three-year time period between 2018 and 2020, yielding a total of 528 and 500 cases, respectively. We then proceeded to reclassify each specimen according to TIS guidelines and calculate the risk of malignancy (ROM) for each category by searching each patients’ histology records, medical history and clinical follow-up. For pleural effusions, 3 (0.57%) cases were classified as ND, 430 (81.44%) cases as NFM, 15 (2.84%) as AUS, 15 (2.84%) as SFM and 65 (12.31%) as MAL. ROM amounted to 0%, 5.3%, 33.33%, 93.33% and 100% for each category, respectively. As far as peritoneal effusions are concerned, 6 (1.2%) were categorized as ND with ROM estimated at 16.66%, 347 (69.4%) as NFM (ROM = 9%), 13 (2.6%) as AUS (ROM = 38.46%), 12 (2.4%) as SFM (ROM = 83.33%) and 122 (24.4%) as MAL (ROM = 100%). Our results underline the utility of the current classification, both as a means of communication between doctors of different specialties and as general guidelines for the further clinical management of patients.

The International System for Reporting Serous Fluid Cytopathology (ISRSFC) was proposed by the International Academy of Cytology and the American Society of Cytopathology. We have applied this system for reporting of pleural effusion cytology and report our experience. All the pleural effusions from January 2019 to June 2020 were retrieved from the database. All these cases were reviewed and recategorized according to the proposed system of 5 categories: non-diagnostic (ND), negative for malignancy (NFM), atypia of uncertain significance (AUS), suspicious for malignancy (SFM), and malignant (MAL). The risk of malignancy (ROM) for each category was evaluated. A total of 939 cases were studied. The age of patients ranged from 2 to 88 years, and the volume of fluid ranged from 1 to 600 ml. There were 41 ND (4.37%), 697 NFM (74.23%), 44 AUS (4.69%), 27 SFM (2.88%), and 130 MAL (13.84%) cases. The ROM for the categories were found to be 87.5%, 51.61%, 88.23%, 87.5%, and 100% respectively. The ISRSFC is a user-friendly system for use in reporting of pleural fluid. The criteria for defining the various categories need to be further elaborative and stricter for this system to be more effective. More studies are required for the estimation of the ROM for each category.

Introduction: The International Academy of Cytology and the American Society of Cytopathology developed the International System of Serous Fluid Cytopathology (TIS) to standardize cytological reports. Effusions in pleural, peritoneal, and pericardial cavities are valuable sources of information for medical diagnosis, especially in oncological scenarios. The TIS classification is divided into five categories: nondiagnostic (ND), negative for malignancy (NFM), atypia of uncertain significance (AUS), suspected malignancy (SFM), and malignant (MAL). It facilitates global communication between specialists, aiming for future clinical management guidelines based on malignancy risk assessment. Methods: This quantitative analytical and retrospective study evaluated serous fluids (pleural, pericardial, and peritoneal) sent to the Instituto de Patologia de Araçatuba (IPAT), São Paulo, Brazil, from public and private hospitals between January 2017 and December 2022. Epidemiological and clinical data were collected from institutional files, including biopsies and immunohistochemical results. Results: The study included 719 patients with 763 serous fluid samples (pericardial, pleural, and peritoneal) analyzed over 6 years. The majority of samples were from pleural effusions (n = 438; 57.4%), followed by peritoneal (n = 293; 38.4%) and pericardial effusions (n = 32; 4.2%). Samples were classified using the International Serous Fluid Cytopathology System (TIS), revealing the following distribution: ND (0.41%), NFM (70.30%), AUS (0.95%), SFM (11.90%), and MAL (16.44%). The risk of malignancy calculated for each category was ND 66.67%, NFM 23.39%, AUS 28.57%, SFM 48.28%, and MAL 84.17%. Conclusion: The ROM was out of the interval proposed by the TIS in all categories. These findings suggest the applicability of TIS even outside of the cancer center environment, although the presented ROM frequencies were out of the recommended range.

The International System for Reporting Serous Fluid Cytopathology (ISRSFC) standardises the reporting of serous effusion cytology under five categories: Non-Diagnostic (ND), Negative for Malignancy (NFM), Atypia of Undetermined Significance (AUS), Suspicious for Malignancy (SFM), and Malignant (M). Very few studies have been conducted so far to confirm the risk of malignancy of the different categories. The main objectives of our study were to classify serous effusions according to the ISRSFC categories and assess their risk of malignancy (ROM) and performance parameters. All serous effusion samples received from January 2019 to December 2020 were reclassified according to the ISRSFC. Using histopathological diagnosis as the gold standard, ROM and performance parameters were calculated. A total of 831 pleural effusion samples were reclassified as follows: ND, 3 (0.4%); NFM, 635 (76.4%); AUS, 65 (7.8%); SFM, 60 (7.2%); and M, 68 (8.2%). For 457 peritoneal effusion samples, the reclassifications were ND, 5 (1.1%); NFM, 368 (80.5%); AUS, 19 (4.2%); SFM, 17 (3.7%); and M, 48 (10.5%). All 12 (100%) pericardial effusions belonged to the NFM category. The ROM for the ND, NFM, AUS, SRM, and M categories was 0%, 2.1%, 33.3%, 94.1%, 100%, respectively, in pleural effusions, and 50%, 4.8%, 22.2%, 83.3%, 100%, respectively, in peritoneal effusions. The ROM was 0% for NFM in pericardial effusions. The ISRSFC is an excellent system for accurately classifying serous effusions with greater reproducibility of reports and better communication between pathologist and clinician.

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. 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). 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. 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.

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

Cytological analysis is part of the initial etiological evaluation of serous effusions. The newly proposed International System for Reporting Serous Fluid Cytopathology (ISRSFC) aims to standardize reporting. All pleural and peritoneal effusion samples admitted for cytological analysis at our institution between 2012 and 2016, and pericardial effusion samples admitted between 2008 and 2018, were reviewed and reclassified according to the ISRSFC. Risk of malignancy (ROM) and performance parameters were calculated. 1496 pleural effusion samples were reclassified: 12(0.8%) non-diagnostic (ND), 944(63.1%) negative for malignancy (NFM), 9(0.6%) atypia of undetermined significance (AUS), 54(3.6%) suspicious of malignancy (SFM) and 477(31.9%) malignant (M). 64 pericardial effusion samples were reclassified: 23(35.9%) NFM, 1(1.6%) AUS, 4(6.3%) SFM and 36(56.2%) M. 763 peritoneal effusion samples were reclassified: 5(0.7%) ND, 457(59.9%) NFM, 12(1.6%) AUS, 37(4.8%) SFM and 252(33%) M. The ROM was, respectively, for each of the aforementioned categories, 57.1%, 23.9%, 50%, 76.2%, 100% in pleural effusions, 100%, 26.3%, 62.5%, 91.7%, 100% in peritoneal effusions and 0% for NFM, 0% for AUS and 100% for M in pericardial effusions. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were, respectively, 61.6%, 100%, 100%, 73.3%, 81.3% for pleural, 100%, 100%, 100%, 100%, 100% for pericardial and 61.2%, 100%, 100%, 70%, 79.7% for peritoneal effusion samples. Serous effusion cytology has a high specificity and positive predictive value and a modest sensitivity and negative predictive value, supporting its role in confirming the diagnosis of malignancy. The ISRSFC will increase standardization and reproducibility in reporting, leading to improved clinical decision-making.

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.

BackgroundCytology of serous effusions is an important diagnostic tool for the diagnosis of cancer, staging, and prognosis of the patient. Herein, we retrospectively applied the International System for Reporting Serous Fluid Cytopathology (TIS) and provided the corresponding risks of malignancy (ROMs).MethodsPleural, pericardial, and peritoneal effusion samples were retrieved from the archives of our department and reclassified according to the TIS. The ROM for each category was calculated based on available surgical follow‐up.ResultsA total of 3790 effusions were studied. Pleural samples (1292) were reclassified as follows: 27 (2.1%) as non‐diagnostic (ND), 1014 (78.5%) as negative for malignancy (NFM), 86 (6.6%) as atypia of undetermined significance (AUS), 29 (2.3%) as suspicious of malignancy (SFM), and 136 (10.5%) as malignant (M). Pericardial samples (241) were reclassified as follows: 4 (1.6%) as ND, 173 (71.8%) as NFM, 10 (4.1%) as AUS, 7 (3%) as SFM, and 47 (19.5%), as M. Peritoneal cases (2257) were re‐categorised as follows: 31 (1.4%) as ND, 1897 (84%) as NFM, 39 (1.7%) as AUS, 53 (2.4%) as SFM, and 237 (10.5%) as M. The respective ROM values for each category were 18.5%, 15%, 45.3%, 93%, and 100% in pleural effusions; 25%, 13.2%, 35%, 100%, and 100% in pericardial effusions; and 19.3%, 10.4%, 43.5%, 100%, and 100% in peritoneal effusions.ConclusionsPleural, pericardial, and peritoneal cytology show high specificity and moderate sensitivity in the evaluation of serous effusions. The ROMs reported in our study were mostly concordant with those published according to the TIS.

Introduction: The International System for Reporting Serous Fluid Cytopathology (ISRSFC) has recently been announced. Pericardial effusion (PE) is a clinical manifestation of a large variety of both neoplastic and non-neoplastic conditions. Herein, we have applied the ISRSFC on reporting PE cytopathology and report our experience in a large academic institution. Method and Materials: After the Institutional Research Board approval, the electronic pathology database of a large academic institution was queried for PEs collected from January 2014 to January 2019. The diagnosis, patient demographics, and specimen volume were recorded for each case. The ISRSFC was applied and the cases were divided into 5 categories: nondiagnostic (ND), negative for malignancy (NFM), atypia of uncertain significance (AUS), suspicious for malignancy (SFM), and malignant (MAL). Each category was evaluated separately. Results: A total of 299 cases were identified, 162 females and 137 males. The age of the subjects ranged from less than a year to 89 years (average 51.25 years). The volume ranged from 3 to 1,700 mL (average 298 mL). There were 252 NFM (84.3%), 13 AUS (4.3%), 4 SFM (1.3%), and 30 MAL (10%) cases. Metastatic lung cancer followed by metastatic breast cancer were the most common malignancies involving pericardial fluid (PF). No cases were diagnosed as ND. However, no mesothelial cells were seen in 97 specimens (38% of the negative cases). None of these patients developed malignant PE in at least 6 months of follow-up. Conclusion: The ISRSFC is a user-friendly reporting system which is easily applicable on serous fluid including PF. The vast majority of PEs was benign (84.3%). Our study shows that the presence of mesothelial cells is not necessary for specimen adequacy in serous effusions as no mesothelial cells were identified in 38% of the negative cases. Metastatic lung carcinoma was the most common diagnosis of malignant effusions.

Background: Serous effusions are a common clinical presentation encountered in cytopathology. The International System (TIS) for Reporting Serous Fluid Cytopathology provides a standardized five-tier diagnostic framework to improve consistency and uniformity in diagnosis and clinical communication. Objective: To categorize serous effusion samples according to TIS and assess the risk of malignancy (ROM) in each category. Methods: This prospective observational study analyzed 438 serous fluid samples (pleural, peritoneal, and pericardial) at a tertiary care center. Cytological smears were categorized into Non-Diagnostic (ND), Negative for Malignancy (NFM), Atypia of Undetermined Significance (AUS), Suspicious for Malignancy (SFM), and Malignant (MAL). ROM was calculated based on follow-up histopathology, immunohistochemistry (IHC), or radiology. Results: Distribution across categories was: ND (1.14%), NFM (90.86%), AUS (1.36%), SFM (2.28%), and MAL (4.33%). The corresponding ROMs were 20%, 11.55%, 66.67%, 80%, and 100%, respectively. ROM varied by fluid type, with the highest predictive value observed in SFM and MAL categories across all sample types. Conclusion: The TIS framework effectively stratifies the risk of malignancy in serous effusions, aiding in diagnostic precision and clinical decision-making. High ROM in AUS and SFM highlights the need for vigilant follow-up and additional investigations in these groups.

A single tertiary institution review of the international system for serous fluid cytopathology and the impact of cell block and ancillary studies on its performance.