The value of a tiered cytology diagnostic reporting system in assessing the risk of malignancy in indeterminate serous effusions

Application of the newly published International System for Reporting Serous Fluid Cytopathology in atypical and suspicious diagnosis: a four-year retrospective analysis

INTRODUCTION

Serous fluids offer crucial diagnostic insights, but inconsistent analysis hampers reporting quality, especially in indeterminate (ID) categories like atypia of undetermined significance (AUS) and suspicious for malignancy (SFM). The 2020 International System for reporting Serous Fluid Cytopathology (TIS) aims to standardize communication and reduce reporting disparities. This study evaluates TIS's role in AUS and SFM categories within our institution.

MATERIALS AND METHODS

A 4-year retrospective search of cytopathology reports from December 2015 to December 2019 for AUS and SFM diagnoses in pleural, ascitic, pericardial fluids, and peritoneal washings was performed and results reclassified using TIS definitions. The risk of malignancy (ROM) was calculated for existing and reclassified diagnoses.

RESULTS

Over 4 years, we received 2998 serous fluid specimens. AUS constituted 2.3% (70 cases), while SFM constituted 0.5% (16 cases). Excluding repeats, 80 cases were TIS-reviewed. Sixteen cases of ID diagnoses were reclassified. Two cases of AUS were changed to negative for malignancy (NFM) and 12 to SFM. Two SFM cases were upgraded to malignancy. ROM shifted from 63% to 60% for AUS and 100% to 85% for SF (TIS's ROM range: AUS: 66% ± 10%; SFM: 82% ± 4.8%).

CONCLUSIONS

This institution's ID diagnosis rate is low. AUS ROM is challenging but aligns with TIS, primarily favoring benign. All SFM diagnoses are highly suspicious but quantitatively inadequate for definitive malignancy, explaining the elevated ROM. AUS rate should gauge quality, not serve as a catch-all category. Algorithmic cytology with cell blocks and ancillary studies aids reclassification. TIS is user-friendly and is a consistent methodology for standardized reporting. Further studies are needed to evaluate ROM and define reproducible diagnostic criteria for each category for better system utilization.

Role of Ancillary Techniques in Reporting Serous Fluid Cytology - "Redefining Categories, Refining Diagnosis"

Background

The "International System of Reporting Serous Fluid Cytology (TIS)" together with cytomorphology promotes the use of ancillary techniques to resolve difficulties in reporting serous fluid cytology.

Objective

To classify serous effusion fluid samples received at our department in line with "TIS", indicating the risk of malignancy (ROM), and directing appropriate usage of ancillary testing.

Materials and Methods

Prospective study carried out from October 2021 to September 2022. The study included all pleural, ascitic, and pericardial fluid samples, reported according to 'TIS'. Flow cytometry and immunocytochemistry were ancillary methods utilized to assist in reporting. Cases with available history and convincing correlations didn't require further assessment.

Results

A total of 1200 serous effusion samples were evaluated including 604 pleural, 591 ascitic, and 5 pericardial fluid samples. After categorization, there were 23 samples in non-diagnostic (ND, 1.9%), 575 in negative for malignancy (NFM, 47.91%), 44 in atypia of undetermined significance (AUS, 3.66%), 64 in suspicious for malignancy (SFM, 5.33%), and 494 in malignant category (MAL, 41.16%). Ancillary studies were beneficial in the recategorization of 26% (11/44) AUS cases, 29.6% (19/64) SFM cases, and it helped refine tumor characteristics in 35.42% (175/494) cases categorized as malignant. Final ROM calculated for each category: ND 25%, NFM 18.6%, AUS 66.6%, SFM 88%, and MAL 100%.

Conclusion

Serous fluid is an easily obtainable sample that can provide opportunities for ancillary testing with clinical implications. In AUS and suspicious category although, diagnostic yield is increased however, a larger number of cases are required to obtain definite results.

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.

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.

Categorisation of peritoneal serous effusions using the International System for Reporting Serous Fluid Cytopathology-A study on gynaecological samples

BACKGROUND

Cytology of serous effusions is an indispensable diagnostic tool for the diagnosis of non-neoplastic as well as neoplastic effusions, aiding in the categorisation, staging, and prognostication of the patient. This study focuses on reclassifying cases of peritoneal fluid cytology following the International System for Reporting Serous Fluid Cytopathology (TIS), highlighting various challenges encountered and adding to the body of data regarding the risk of malignancy (ROM), focussing on peritoneal effusions due to gynaecological causes.

METHODS

Peritoneal effusion samples were retrieved from our department's archives and reclassified according to the TIS. The ROM for each category was calculated based on available surgical follow-up.

RESULTS

A total of 818 peritoneal effusions were studied. Following the definitions and guidelines of the TIS, the cases were reclassified with 125 (15.2%) in the category of non-diagnostic (ND), 595 (72.7%) as negative for malignancy (NFM), 26 (3.2%) as atypia of undetermined significance (AUS), 12 (1.5%) as suspicious for malignancy (SFM), and 60 (7.3%) as malignant (MAL). The respective ROM values for each category were 16.9%, 12.1%, 50%, 80%, and 100%, respectively. By considering the MAL and SFM groups as positive, and the ND, NFM, and AUS groups as negative, the diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were determined as 85.2%, 36.7%, 99.1%, 91.7%, and 84.5%, respectively.

CONCLUSIONS

Peritoneal cytology categorisation following the proposed TIS offered a practical approach for categorisation of the fluids received. The ROMs reported in our study were mostly concordant with those published according to the TIS.

Risk of malignancy assessment of the International System for Reporting Serous Fluid Cytopathology: Experience in a community hospital setting and comparison with other studies

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

The findings suggested the necessity for each laboratory to perform its own ROM analysis based on its statistics for ISRSFC-tiered classification terminology.

Cytomorphological and immunohistochemical features of pancreatic ductal adenocarcinoma in serous fluids

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) represents the most common primary pancreatic malignancy. An understanding of the cytomorphologic features of conventional ductal adenocarcinoma and its variants is important to ensure accurate diagnoses.

METHODS

The clinicopathological and cytological data of serous fluids in PDAC patients were obtained from the electronic medical records and pathology database. All samples were analyzed and reclassified according to the "The International System for Reporting Serous Fluid Cytopathology" guidelines. Cytomorphologic features were examined with SurePath automatically prepared slides and stained using the Pap method in malignant (MAL) effusion specimens from 21 patients with PDAC. Immunocytochemical staining was conducted on 12 cell blocks from MAL PDAC effusion.

RESULTS

A total of 137 serous fluids specimens of PDACs were included, among which 61 (44.5%), 9 (6.6%), 13 (9.5%), 52 (38.0%), and 2 (1.5%) patients were classified into malignancy, suspicious for malignancy, atypia of undetermined significance, negative for malignancy and nondiagnostic groups, respectively. The key cytologic features for the conventional type of PDAC included cohesive clusters of ductal cells in glandular crowding and disorganized "drunken honeycomb" pattern or intercalated duct-like structure with anisonucleosis, cytoplasmic vacuoles, and concomitant "Indian-file" configuration. Undifferentiated carcinoma was comprised of enlarged, undifferentiated, pleomorphic MAL cells. Adenosquamous carcinoma could show glandular and/or squamous differentiation. Colloid carcinoma was composed of three-dimensional cancer cell clusters floating in thick mucin.

CONCLUSION

Crowding and disorganized "drunken honeycomb" pattern or intercalated duct-like structure with anisonucleosis, may represent an important clue for diagnosing PDAC in serous fluids. Immunocytochemical staining in combination with review of medical records and cytomorphological data can serve as useful adjuncts for distinguishing between PDAC and its variants.

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

Objectives:

Cytological examination of effusion sample is a preliminary and minimally invasive method for the diagnosis of body fluids. Recently, the International System For Reporting Serous Fluid Cytopathology (ISRSFC) and the Indian Academy of Cytologist (IAC) have published guidelines for reporting effusion cytology and calculating the risks of malignancy (ROMs) for each defined category. We report our 2 years of experience in reclassifying and assessing the feasibility of applying ISRFSC and IAC categories to effusion fluid and to provide an estimate of the risk of malignancy for each diagnostic category.

Material and Methods:

Cytological reports of patients from January 2019 to December 2020 were retrieved and reclassified into a five-tiered classification scheme as per ISRSFC guidelines. Cellblock and immunohistochemistry were performed in selected cases. Clinico radiological and histopathological information were obtained and correlated with the cytological findings wherever available.

Results:

In the study, 652 cases were included during the 2 years. Out of these, 328 (50.3%) were women and 314 (47.3%) were men. Patient’s ages ranged between 2 92 years with a mean age of 47.4 years. There were 366 (56.1%) cases of ascitic fluid followed by 262 (40.1%) cases of pleural fluid and 24 (3.8%) cases of pericardial fluid in the analysis. Of all the cases, 13 (2%) were non-diagnostic (ND), 464 (71.6%) were negative for malignant (NFM) cells, 16 (2.4%) were atypia of uncertain significance, 31 (4.7%) were suspicious of malignancy, and 125 (19.3%) were malignant. Cellblock was prepared in 65 cases. Lung cancer followed by breast cancer was the most common malignancies involving the pleural effusion and ovarian cancer was the most common cause of peritoneal effusion. ROM for each diagnostic category was 23% for ND, 25% for NFM, 56% for the atypical category, 80.6% in suspicious, and 90% were for positive for malignancy category.

Conclusion:

The use of a five-tiered system as per the ISRFC and IAC guidelines are feasible for the standardized reporting of effusion samples, thus avoiding subjective variation of reporting.

A retrospective analysis of serous effusions based on the newly proposed international system for reporting serous fluid cytopathology: a report of 3633 cases in an oncological center

Background

The International System for Reporting Serous Fluid Cytopathology (TIS) was recently proposed. We retrospectively applied TIS recommendations for reporting the cytological diagnosis of serous effusions and reported our experience.

Methods

All the serous effusions from January 2018 to September 2021 were retrieved from the database. Recategorization was performed using the TIS classification, the risk of malignancy (ROM) was calculated for each TIS category. In addition, on the basis of the original TIS classification, we further subdivided the TIS category IV (suspicious for malignancy, SFM) into 2 groups (IVa and IVb) according to cytological characteristics (quality and quantity) to explore the necessity of SFM subclassification. The performance evaluation was carried out using different samples (pleural, peritoneal and pericardial effusions) and preparation methods (conventional smears, liquid-based preparations and cell blocks).

Results

A total of 3633 cases were studied: 17 (0.5%) were diagnosed as ‘nondiagnostic’ (I, ND), 1100 (30.3%) as ‘negative for malignancy’ (II, NFM), 101 (2.8%) as ‘atypia of undetermined significance’ (III, AUS), 677 (18.6%) as ‘suspicious for malignancy’ (IV, SFM), and 1738 (47.8%) as ‘malignant’ (V, MAL). The ROMs for the categories were 38.5%, 28.6%, 52.1%, 99.4% and 100%, respectively. The ROM for SFM was significantly higher than that for AUS (P < 0.001), while the difference between the ROMs for IVa and IVb was insignificant. The sensitivity, negative predictive value (NPV) and diagnostic accuracy of liquid-based preparations were all superior to those of conventional smears and cell blocks in detecting abnormalities. Using the three preparation methods simultaneously had the highest sensitivity, NPV and diagnostic accuracy.

Conclusion

Serous effusion cytology has a high specificity and positive predictive value (PPV), and TIS is a user-friendly reporting system. Liquid-based preparations could improve the sensitivity of diagnosis, and it is best to use three different preparation methods simultaneously for serous effusion cytologic examination.

Risk Stratification of Pleural Fluid Cytology Based on the International System for Reporting Serous Fluid Cytology in a Tertiary Care Centre

BACKGROUND

The International Academy of Cytology and the American Society of Cytopathology proposed the international system for reporting serous fluid cytology (TISRSFC) in 2019 to form uniform reporting terminologies for fluid cytology. This system defines a spectrum of diagnostic categories to be used in daily clinical practice. Fluid cytology is a widely accepted, cost-effective, minimally invasive earliest diagnostic method for the investigation that aids management decisions. The present study aims to reclassify pleural fluid cytology and calculate the risk of malignancy (ROM) for each diagnostic category.

MATERIAL AND METHODS

It is a retrospective 2 years observational study comprising 690 pleural fluid specimens. Retrospective reviews were performed, and cases were reclassified into five categories as per TISRSFC. Immunohistochemistry was applied whenever needed. Cytological diagnosis was correlated with respective histopathology and/or clinical and/or radiological diagnosis. ROM was calculated for all diagnostic categories.

RESULTS

In the present study of 690 cases, 7.97% were non-diagnostic (ND), 84.1% cases were negative for malignancy (NFM), 0.87% were atypia of undetermined significance (AUS), 1.16% were suspicious for malignancy (SFM), and 5.94% were malignant (MAL). Cell blocks were prepared in 33 (4.8%) cases and immunohistochemistry was applied in 7 cases. The commonest site for pleural fluid metastasis was the lungs, accounting for 4.64% (32/690) cases. Further, ROM was calculated for all diagnostic categories as follows: (1) ND: 30.9%, (2) NFM: 12.9%, (3) AUS: 100%, (4) SFM: 100%, and (5) MAL: 90.2%.

CONCLUSION

Cytological examination of pleural fluids is an accurate, prompt, and affordable technique. This standardized ISRSFC reporting system will maintain uniformity and reproducibility in reporting, leading to improved clinical decision-making of pleural fluids.

Application of the International System for Reporting Serous Fluid Cytopathology (TIS): A Retrospective Institutional Study

BACKGROUND

Cytology of serous effusions is an important diagnostic tool for the diagnosis of cancer, staging and prognosis of the patient. Herein, we retrospectively applied the TIS on reporting serous cytopathology and provided the corresponding risk of malignancy (ROM).

METHODS

Pleural, 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.

RESULTS

A total 3790 effusions were available for the study. 1292 pleural samples were reclassified: 27 (2.1%) non-diagnostic (ND), 1014 (78.5 %) negative for malignancy (NFM), 86 (6.6 %) atypia of undetermined significance (AUS), 29 (2.3 %) suspicious of malignancy (SFM) and 136 (10.5%) malignant (M). 241 pericardial samples were reclassified: 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. 2257 peritoneal cases were re-categorized 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 ROM was, respectively, for each of the aforementioned categories, 18.5%, 15%, 45.3%, 93%, 100% in pleural effusions, 25%, 13.2%, 35%, 100%, 100% in pericardial effusions and 19.3%, 10.4%, 43.5%, 100%, 100% in peritoneal effusions.

CONCLUSIONS

Pleural, pericardial, and peritoneal cytology show high specificity and moderate sensitivity in the evaluation of serous effusions. The ROM reported in our study was mostly concordant with ROM published by the TIS.

Application of the International System for Reporting Serous Fluid Cytopathology with Cytohistological Correlation and Risk of Malignancy Assessment

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.

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.

Application of the International System for Reporting Serous Fluid Cytopathology in routine reporting of pleural effusion and assessment of the risk of malignancy

INTRODUCTION

The International System for Reporting Serous Fluid Cytopathology (ISRSFC) was proposed by the International Academy of Cytology and the American Society of Cytopathology.

AIM OF THE STUDY

We have applied this system for reporting of pleural effusion cytology and report our experience.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Cytohistological Correlation in Pleural Effusions Based on the International System for Reporting Serous Fluid Cytopathology

The International System for Reporting Serous Fluid Cytology (TIS) was recently developed. Given its novelty, most studies looking into the risk of malignancy (ROM) of serous effusion diagnostic categories were published before the development of TIS. We searched the database of our department for pleural effusions diagnosed in the last five years, excluding those without a corresponding pleural biopsy. Cases were reviewed and reclassified according to the TIS. A cytohistological correlation was performed. In total, 350 pleural effusion specimens with one or more corresponding pleural biopsies were included. After reclassification, 5 (1.43%) were nondiagnostic (ND), 253 (72.29%) were negative for malignancy (NFM), 7 (2.00%) had atypia of unknown significance (AUS), 14 (4.00%) were suspicious for malignancy (SFM), and 71 (20.57%) were malignant (MAL). Calculated ROM was 40% for ND, 20.16% for NFM, 42.86% for AUS, 78.57% for SFM, and 100% for MAL. Effusion cytology sensitivity and specificity were 60.29% and 98.56%, respectively. This is the first publication looking into the cytohistological correlation of a retrospective cohort of pleural effusions based on the TIS. We add to the body of data regarding the ROM for TIS categories, highlighting areas of potential future research.

A retrospective analysis of pleural effusion specimens based on the newly proposed International System for Reporting Serous Fluid Cytopathology

BACKGROUND

Recently, the International System for Reporting Serous Fluid Cytopathology (TIS) has been established, with an aim to standardize reporting and guide clinical decision making.

METHODS

The cytological and clinicopathological data of pleural effusions were retrieved from the pathology database and electronic medical records. All specimens were evaluated and reclassified in accordance with the TIS recommendations. Finally, the risk of malignancy (ROM) and performance parameters were measured.

RESULTS

A total of 2454 pleural effusion specimens were included, among which 30 (1.2%), 1670 (68.1%), 151 (6.2%), 54 (2.2%) and 549 (22.4%) patients were classified into non-diagnostic (ND), negative for malignancy (NFM), atypia of undetermined significance (AUS), suspicious for malignancy (SFM) and malignancy (MAL) groups, respectively. The most commonly diagnosed malignancies were lung cancer (48.4%), ovary cancer (10.2%), breast cancer (7.5%), and 21.3% unknown primary site (UPS). Among the 36 UPS patients, the most common site of origin was lung (36.1%), followed by ovary (13.9%) and breast (11.1%) via immunocytochemistry of cell block. The calculated ROM values were 26.7%, 12%, 62.3%, 77.8% and 100% for ND, NFM, AUS, SFM and MAL groups, respectively. When considering MAL as the only positive group, the diagnostic accuracy, sensitivity, specificity, positive and negative predictive values were determined to be 95.2%, 81.9%, 100%, 100% and 93.6%, respectively.

CONCLUSION

The newly proposed TIS is an easy-to-master, user-friendly, and standardized classification system, especially when applying on pleural effusions. An adequate serous sample, application of immunocytochemistry, review of cytomorphological data and past medical history could enhance the accuracy of cytological diagnosis.