The international system for reporting serous fluid cytopathology-diagnostic categories and clinical management

Clinicopathological and molecular characterization of non-small cell lung cancer with pericardial effusions

BACKGROUND

Cytological evaluation is essential for assessing pericardial effusions (PEs) in non-small cell lung cancer (NSCLC). This study retrospectively examined the clinicopathological, molecular, and prognostic characteristics of patients with NSCLC with PE.

METHODS

Clinical data from 80 patients with NSCLC with PE treated at an academic center over the course of 15 years were reviewed. PE specimens were categorized according to the International System for Reporting Serous Fluid Cytopathology (ISRSFC). The analysis included patient demographics, molecular alterations, cytopathology, histology, and survival outcomes.

RESULTS

Of the 80 patients, 36 (45%) were female and 90% had stage IV disease. A smoking history was noted in 58 patients (72.5%), and 22 patients (27.5%) presented with tamponade. Lung adenocarcinoma predominated (87.5%). The ISRSFC categorized 25% of the specimens as negative for malignancy (NFM), 7.5% as atypia of undetermined significance (AUS), 3.75% as suspicious for malignancy (SFM), and 63.75% as malignant (MAL). Immunohistochemistry in 57 specimens identified thyroid transcription factor 1 (65%) as the most frequently positive marker. Molecular analysis revealed p53 mutations (59.1%) as the most prevalent, followed by KRAS (34.1%) and EGFR (15.9%). Kaplan-Meier analysis showed significantly better survival for NFM patients than non-NFM patients (MAL, SFM, and AUS; p = .0036). Bloody PEs and tamponade were associated with worse outcomes. The immunotherapy group achieved the most prolonged survival among stage IV patients (9.07 months; p = .017). Cox regression confirmed cytology-negative status as an independent prognostic factor.

CONCLUSIONS

Cytological evaluation and ISRSFC classification are crucial for NSCLC-associated PEs. A multidisciplinary approach integrating cytology, immunohistochemistry, and molecular profiling is essential for optimal management and prognosis.

Morphometric analysis of neoplastic cell clusters in high-grade serous ovarian cancer ascites identifies a promising prognostic factor: a retrospective study

High-grade serous carcinoma of the ovary is the most frequent intraperitoneal malignancy in women. It is associated with a poor prognostic outcome owing to the late appearance of clinical signs leading to a delayed diagnosis, and with resistance to platinum-based chemotherapy. One of the clinical signs is the development of ascites. The detection of neoplastic cells in ascites fluid is important as it indicates tumor progression and is associated with shorter survival. Microscopic cytospin analysis of this fluid reveals the cytological and architectural features of the neoplastic cells, allowing the pathologist to identify rapidly the malignancy and the histologic type. In association with immunocytochemistry, this process ensures a definite diagnosis and provides a specific etiology. Our objective was to provide proof-of-principle that the automatized analysis of general cytomorphological criteria, such as carcinomatous cell clustering, in malignant ascites fluid is of prognostic value in high-grade serous carcinoma. We performed a retrospective analysis of the ascites fluid of 24 advanced-stage high-grade serous ovarian cancer patients naïve of treatment. We found that the low number of neoplastic cell clusters in fluid was significantly associated with shorter overall and progression-free survival after adjusting for WHO performance status, Sugarbaker score, age and BMI. These results were independent of the peritoneal implantation of neoplastic cells. We believe this is a promising strategy to improve high-grade serous carcinoma diagnostics using a more informative but simple analysis of ascites tumor cell morphology.

Re-Categorization and Risk of Malignancy of Atypical Effusions According to the International System for Reporting Serous Fluid Cytopathology (TIS): An Institutional Experience

BACKGROUND

Serous effusion fluids serve as crucial cytological materials in diagnosing the underlying causes of fluid accumulation in various body cavities. The International System for Reporting Serous Fluid Cytopathology (TIS) outlined atypia of undetermined significance (AUS) and suspicious for malignancy (SFM) as two intermediate categories for atypical fluids.

MATERIALS AND METHODS

In our study, cases diagnosed as "atypical" by an experienced cytopathologist in the Hacettepe University Department of Pathology, between 2014 and 2023, were re-categorized according to TIS. The risk of malignancy (ROM) for AUS and SFM categories was calculated. Additionally, cases were re-evaluated according to the 5-tier categorical system by two observers with different level of experience.

RESULTS

A total of 3501 effusion fluids were included in the study, evaluated between 2014 and 2023. 50.7% of the cases were male, and 49.3% were female. 55.2% of the cases were pleural fluid, 41.5% were peritoneal fluid, and 3.3% were pericardial fluid. Two hundred sixty five cases (7.6%) were non-diagnostic, 2160 (61.7%) were negative for malignancy, 111 (3.2%) were AUS, 83 (2.4%) were SFM, and 883 (25.2%) were malignant (M). ROM calculated 27% for AUS, 49% for SFM 49%. The interobserver agreement for AUS was 46% with kappa value of 0.162, and 42% for SFM with kappa value of 0.188.

CONCLUSION

The differentiation of atypical cases into AUS and SFM is effective in determining the ROM. The interobserver agreement tends to be lower in intermediate categories compared to others, emphasizing the potential significance of clinical expertise in diagnosis.

Pericardial fluid evaluation: Diagnostic yield and cytology-histology correlation

BACKGROUND

Pericardial effusion can be due to any etiology but may cause significant morbidity and mortality; however, malignant effusions are rare, and accurate and timely diagnosis is essential for appropriate further management. Data on the actual comparison of pericardial cytology and surgical specimens are limited, and this study was conducted to evaluate an institutional cohort and compare these two samples.

METHODS

The institutional electronic database system was retrospectively searched between January 2019 and December 2023 for pericardial biopsies/surgical specimens (PSSs) and cytology.

RESULTS

A total of 202 surgical specimens of the pericardium were identified from patients with a median age of 67 years and a range of 18-97 years. Of these 202 cases, 190 specimens also underwent cytological evaluation, which included 153 cases that were negative for malignancy, nine cases that were indeterminate/atypical, and 28 cases that were positive for malignancy. Agreement between cytology and PSSs was reached in 172 cases, with 153 being benign and 19 being malignant. However, a cytology-histology discrepancy was found in 18 cases. Of these 18 cases, nine showed positive cytology but all had negative concurrent PSSs except for one with focal atypia, and the remaining nine were indeterminate/atypical on cytology. Eight of these nine indeterminate cases were negative on the PSS, whereas one atypical cytology case with low cellularity showed a positive PSS.

CONCLUSIONS

If atypical cases are excluded, cytology demonstrates a better diagnostic yield for detecting malignancy compared to surgical specimens (n = 28 cases vs. n = 20 cases, respectively).

Higher sensitivity of pericardial fluid cytology than biopsy in malignant effusions with potential explanation of false-negative cytology: A multi-institutional analysis

OBJECTIVE

Malignant pericardial effusions are associated with a poor prognosis. Pericardial fluid cytology and pericardial biopsy are the primary methods for diagnosis. This study aimed to conduct a multi-institutional analysis to compare the diagnostic sensitivity of cytology and biopsy, and to investigate potential explanations for false-negative results in cytology.

METHODS

A retrospective review of pericardial fluid cytology cases with concurrent biopsy was conducted across four different institutions. Results were compared using standard statistical methods with attention to sensitivity and histologic distribution. False-negative cytology cases were investigated for further exploration.

RESULTS

A total of 309 cases were collected, of which 99 (32.0%) were confirmed malignant through repeat sampling or clinical history. Pericardial fluid cytology and biopsy identified 84 and 64 malignant cases, respectively. Our findings confirmed significantly higher sensitivity of cytology compared to biopsy (84.8% vs 65.7%). The most common sites of origin were lung, breast, and gastrointestinal, with adenocarcinoma being the most prevalent histologic subtype. Histologic review of 12 false-negative cytology cases revealed three key explanations; lymphoma was the most common missed diagnosis (33.3%); fibrinous pericarditis obscures neoplastic cells on the pericardial surface; and pericardial involvement can be seen without extension into the pericardial space.

CONCLUSION

This study demonstrated diagnostic superiority of pericardial fluid cytology over biopsy in the evaluation of malignant pericardial effusions. We identified several limitations in fluid cytology causing false negatives. In the context of an underlying malignancy with pericardial effusion, pathologists should consider immunohistochemistry studies to aid on the diagnosis.

Diagnostic utility of transfer learning by using convolutional neural network for cytological diagnosis of malignant effusions

INTRODUCTION

Cytological analysis of effusion specimens provides critical information regarding the diagnosis and staging of malignancies, thus guiding their treatment and subsequent monitoring. Keeping in view the challenges encountered in the morphological interpretation, we explored convolutional neural networks (CNNs) as an important tool for the cytological diagnosis of malignant effusions.

MATERIALS AND METHODS

A retrospective review of patients at our institute, over 3.5 years yielded a dataset of 342 effusion samples and 518 images with known diagnoses. Cytological examination and cell block preparation were performed to establish correlation with the gold standard, histopathology. We developed a deep learning model using PyTorch, fine-tuned it on a labelled dataset, and evaluated its diagnostic performance using test samples.

RESULTS

The model exhibited encouraging results in the distinction of benign and malignant effusions with area under curve (AUC) of 0.8674, F-measure or F1 score which denotes the harmonic mean of precision and recall, to be 0.8678 thus, demonstrating optimal accuracy of our CNN model.

CONCLUSION

The study highlights the promising potential of transfer learning in enhancing the clinical pathology laboratory efficiency when dealing with malignant effusions.

Clinical Significance of Primary Tumor Resection in Perihilar Cholangiocarcinoma with Positive Peritoneal Lavage Cytology

BACKGROUND

The prognostic impact of positive peritoneal lavage cytology (CY+) in patients with perihilar cholangiocarcinoma (PHC) remains unclear. The present study investigated the clinical significance of primary tumor resection of CY+ PHC.

METHODS

We retrospectively evaluated 282 patients who underwent surgery for PHC between September 2002 and March 2022. The patients' clinicopathological characteristics and survival outcomes were compared between the CY negative (CY-) resected (n = 262), CY+ resected (n = 12), and CY+ unresected (n = 8) groups. Univariate and multivariate analyses were performed to identify prognostic factors for overall survival.

RESULTS

The expected residual liver volume was significantly higher in the CY+ resected group (61%) than in the CY- resected (47%) and CY+ unresected (37%) groups (p = 0.004 and 0.007, respectively). The CY+ resected group had a higher administration rate of postoperative therapy than the CY- resected group (58% vs. 16%, p = 0.002). Overall survival of the CY+ resected group was similar to that of the CY- resected group (median survival time [MST] 44.5 vs. 44.6, p = 0.404) and was significantly better than that of the CY+ unresected group (MST 44.5 vs. 17.1, p = 0.006). CY positivity was not a prognostic factor according to a multivariate analysis in patients with primary tumor resection.

CONCLUSIONS

The CY+ resected group showed better survival than the CY+ unresected group and a similar survival to that of the CY- resected group. Resection of the primary tumor with CY+ PHC may improve the prognosis in selected patients.

Pulmonary Cytopathology: Current and Future Impact on Patient Care

Small biopsies of lung are routinely obtained by many methods, including several that result in cytologic specimens. Because lung cancer is often diagnosed at a stage for which primary resection is not an option, it is critical that all diagnostic, predictive, and prognostic information be derived from such small biopsy specimens. As the number of available diagnostic and predictive markers expands, cytopathologists must familiarize themselves with current requirements for specimen acquisition, handling, results reporting, and molecular and other ancillary testing, all of which are reviewed here.

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.

The International System for Reporting Serous Fluid Cytopathology: A Systematic Review and Meta-Analysis of Diagnostic Test Accuracy Studies

This is the first systematic review and meta-analysis of The International System (TIS) for reporting serous fluid cytopathology. Our aims were to present the pooled malignancy rate of each TIS reporting category and the diagnostic accuracy of cytology using this system. Database search using a predefined strategy was followed by study selection, data extraction, study quality assessment, and statistical analysis. Data derived from 16 eligible studies were pooled. The pooled rates of malignancy were as follows: 27% (95% CI; 16%-41%) for "nondiagnostic" (ND), 11% (95% CI; 7%-18%) for negative for malignancy" (NFM), 49% (95% CI; 37%-61%) for "atypia of undetermined significance" (AUS), 90% (95% CI; 81%-95%) for "suspicious for malignancy" (SFM), and 100% (95% CI; 98%-100%) for "positive for malignancy" (MAL). Studies performed exclusively in cancer hospitals showed higher pooled malignancy rates, compared with academic and community hospitals serving the general population, in the ND [40% (95% CI; 21%-62%) vs. 22% (95% CI; 11%-39%)], NFM [20% (95% CI; 13%-30%) vs. 9% (95% CI; 5%-17%)], and AUS categories [55% (95% CI; 47%-63%) vs. 46% (95% CI; 31%-62%)]. Notably, the difference was significant in the NFM category ( P =0.04). When both SFM and MAL cytology interpretations were considered as malignant outcomes, the pooled sensitivity and specificity were 68.74% (95% CI; 59.90%-76.39%) and 98.81% (95% CI; 98.18%-99.22%), respectively. In addition, the diagnostic odds ratio (DOR) was found to be 170.7 (95% CI; 96.2-303.3). Despite its strengths, our study also had some limitations. Therefore, future large-scale longitudinal studies could strengthen the findings of this review.

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.

Evaluating Diagnostic Clarity: The Comparative Efficacy of BlueStain in Serous Effusion Cytology under the International System for Reporting Serous Fluid Cytopathology Reporting Framework

Serous effusion cytology is a pivotal diagnostic and staging tool in clinical pathology, valued for its simplicity and cost-effectiveness. Staining techniques such as Giemsa and Papanicolaou are foundational, yet the search for rapid and efficient alternatives continues. Our study assesses the efficacy of an in-house-developed BlueStain, a toluidine blue variant, within the International System for Reporting Serous Fluid Cytopathology (TIS), aiming to optimize diagnostic clarity and resource use.

MATERIALS AND METHODS

This section provides details on the cohort of 237 patients with serous effusions, the ethical approval process, sample collection, and staining procedures with BlueStain, Papanicolaou, and Giemsa. It also describes the microscopic evaluation criteria, scoring system, and statistical methods used to compare the stains.

RESULTS

BlueStain demonstrated notable performance, particularly in identifying malignant cells, presenting a competitive alternative to the Papanicolaou stain, which, despite higher quality indices in other categories, requires more resources and time. The study revealed that BlueStain might offer a valuable balance between quality and efficiency, especially in cases where rapid diagnostic turnaround is essential.

CONCLUSIONS

Our findings suggest that BlueStain is a viable staining method in the context of serous effusions, capable of providing detailed cytomorphological analysis. While traditional stains hold their place for their established diagnostic clarity, BlueStain offers a rapid and resource-optimized alternative. The absence of definitive diagnostic criteria in the atypical category and the inherent sample heterogeneity underscores the necessity for adaptable staining methods like BlueStain. The study highlights the potential trade-offs between detail and practicality in staining techniques, advocating for further research into innovative methods that do not compromise diagnostic precision for cost and time efficiency.

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.

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.

A Novel Validated Real-World Dataset for the Diagnosis of Multiclass Serous Effusion Cytology according to the International System and Ground-Truth Validation Data

INTRODUCTION

The application of artificial intelligence (AI) algorithms in serous fluid cytology is lacking due to the deficiency in standardized publicly available datasets. Here, we develop a novel public serous effusion cytology dataset. Furthermore, we apply AI algorithms on it to test its diagnostic utility and safety in clinical practice.

METHODS

The work is divided into three phases. Phase 1 entails building the dataset based on the multitiered evidence-based classification system proposed by the International System (TIS) of serous fluid cytology along with ground-truth tissue diagnosis for malignancy. To ensure reliable results of future AI research on this dataset, we carefully consider all the steps of the preparation and staining from a real-world cytopathology perspective. In phase 2, we pay special consideration to the image acquisition pipeline to ensure image integrity. Then we utilize the power of transfer learning using the convolutional layers of the VGG16 deep learning model for feature extraction. Finally, in phase 3, we apply the random forest classifier on the constructed dataset.

RESULTS

The dataset comprises 3,731 images distributed among the four TIS diagnostic categories. The model achieves 74% accuracy in this multiclass classification problem. Using a one-versus-all classifier, the fallout rate for images that are misclassified as negative for malignancy despite being a higher risk diagnosis is 0.13. Most of these misclassified images (77%) belong to the atypia of undetermined significance category in concordance with real-life statistics.

CONCLUSION

This is the first and largest publicly available serous fluid cytology dataset based on a standardized diagnostic system. It is also the first dataset to include various types of effusions and pericardial fluid specimens. In addition, it is the first dataset to include the diagnostically challenging atypical categories. AI algorithms applied on this novel dataset show reliable results that can be incorporated into actual clinical practice with minimal risk of missing a diagnosis of malignancy. This work provides a foundation for researchers to develop and test further AI algorithms for the diagnosis of serous effusions.

The WHO system versus the Papanicolaou society of cytopathology system for reporting pancreaticobiliary cytology for risk stratification-which is better?

BACKGROUND

Recently, the World Health Organization (WHO) has proposed a reporting system for pancreaticobiliary cytopathology. We applied this classification for pancreatic lesion samples by fine needle aspiration (FNA) and compared the results to the previous classification of the Papanicolaou Society of Cytopathology (PSC) system for risk stratification.

METHODS

The computerized database was searched for all pancreatic endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) and transabdominal ultrasound-guided FNA (TUS-FNA) samples from 2016 to 2020 and cases were reassigned as per the PSC and the WHO diagnostic categories. Cases with follow-up, clinicoradiological, and/or histopathology were included in the study. The risk of malignancy (ROM) was calculated across all diagnostic categories based on clinical data, imaging data, and histopathology wherever available.

RESULTS

There were a total of 625 pancreatic FNA. In 230 cases, follow-up information was available which included 116 EUS and 114 TUS-FNA samples. The ROM for PSC categories I-VI was 40%, 19.7%, 28.6%, 57.1%, 94.7%, and 97.9% and for the WHO categories (I-VII), it was 60%, 21.3%, and 35.7%, not representative, not applicable, 94.7% and 94.9%. The overall sensitivity and specificity of PSC was 68.2% and 96.2% when categories V and VI were taken as positive and 78.9% and 93.3% for WHO when categories VI and VII were taken as positive.

CONCLUSIONS

Pancreatic FNA samples reported as per the WHO system showed better sensitivity as compared to the PSC system resulting in better risk stratification and consequently better patient management. The overall high specificity and moderate sensitivity reaffirm the utility of FNA in pancreatic lesions.

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.

Claudin-4 immunocytochemistry is specific and sensitive for the diagnosis of malignant carcinomatous effusions: Results from a pilot study

BACKGROUND

Claudin-4, a tight junction associated protein expressed in epithelial cells, is purported as a highly specific and sensitive marker for epithelial malignancies. Our aim was to assess the sensitivity, specificity and real-time utility of claudin-4 immunocytochemistry (ICC) in the diagnostic work-up of suspected malignant effusions.

METHODS

Claudin-4 (3E2C1 clone) ICC was performed prospectively in effusion cell blocks where other ICC markers were being performed as part of reporting over 3 months. Based on claudin-4 staining in unequivocal malignant and reactive effusions, the sensitivity and specificity was calculated. In cases signed out as inconclusive encompassing atypia of undetermined significance (AUS) and suspicious for malignancy (SFM) and negative for malignancy, change in diagnostic category based on addition of claudin-4 ICC was assessed.

RESULTS

Study included 107 effusions. Claudin-4 stained 100% of metastatic adenocarcinomas including those with primaries in lung, breast, ovary, female genital tract, gastrointestinal tract and pancreatic-biliary tract, and was negative in all reactive mesothelial and mesothelioma effusions with sensitivity of 100% (48/48) and specificity of 95% (20/21) for adenocarcinoma. Claudin-4 upgraded the diagnostic category to positive in 70% (16/23) of SFM, 20% (1/5) of AUS, and in 50% (5/10) of negative effusions. Among cases with confirmed serosal involvement status on follow-up, claudin-4 showed sensitivity, specificity, positive predictive value and negative predictive values of 85% (11/13), 100% (3/3), 100% (10/10) and 75% (3/4), respectively, for metastatic adenocarcinoma.

CONCLUSION

Claudin-4 as a single marker is sensitive and specific for adenocarcinoma and is a valuable addition to the ICC armamentarium.

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.

High sensitivity flow cytometry immunophenotyping increases the diagnostic yield of malignant pleural effusions

Diagnosing malignant pleural effusions (MPE) is challenging when patients lack a history of cancer and cytopathology does not detect malignant cells in pleural effusions (PE). We investigated whether a systematic analysis of PE by flow cytometry immunophenotyping (FCI) had any impact on the diagnostic yield of MPE. Over 7 years, 570 samples from patients with clinical suspicion of MPE were submitted for the FCI study. To screen for epithelial malignancies, a 3-color FCI high sensitivity assay was used. The FCI results, qualified as "malignant" (FCI+) or "non-malignant" (FCI-), were compared to integrated definitive diagnosis established by clinicians based on all available information. MPE was finally diagnosed in 182 samples and FCI detected 141/182 (77.5%). Morphology further confirmed FCI findings by cytopathology detection of malignant cells in PE (n = 91) or histopathology (n = 29). Imaging tests and clinical history supported the diagnosis in the remaining samples. The median percentage of malignant cells was 6.5% for lymphoma and 0.23% for MPE secondary to epithelial cell malignancies. FCI identified a significantly lower percentage of EpCAM+ cells in cytopathology-negative MPE than in cytopathology-positive cases (0.02% vs. 1%; p < 0.0001). Interestingly, 29/52 MPE (55.8%) where FCI alerted of the presence of malignant cells were new diagnosis of cancer. Overall, FCI correctly diagnosed 456/522 samples (87.4%) suitable for comparison with cytopathology. These findings show that high sensitivity FCI significantly increases the diagnostic yield of MPE. Early detection of FCI + cases accelerates the diagnostic pathway of unsuspected MPE, thus supporting its implementation in clinical diagnostic work-up as a diagnostic tool.

Predictive impacts of peritoneal washing cytology for surgical resection-intended pancreatic cancer cases: Establishment of planned staging laparoscopy criteria

BACKGROUND

Staging laparoscopy (SL) has been advocated for pancreatic cancer, mainly to evaluate the peritoneal washing cytology (CY) status, which seems to impact the prognosis of pancreatic cancer. To establish an optimal treatment strategy for CY positive (CY+) pancreatic cancer cases, real-world clinical data about CY status-depending surgical outcomes should be accumulated.

METHODS

Peritoneal washing samples were collected from 183 consecutive patients who could be classified as either resectable or borderline resectable (BR) pancreatic cancer between January 2012 and December 2020. Correlations between the CY status and other clinicopathological parameters with the recurrence patterns and survival outcomes were examined. In addition, we analyzed several risk factors for the CY+ status and attempted to identify the patient population that may benefit most from SL.

RESULTS

A total of 24 of the 183 patients were CY+. Peritoneal recurrence occurred more frequently in CY+ cases than in CY- cases (29% vs. 6%, p < .001) and median survival time after surgery was significantly shorter in CY+ cases than in CY- cases (28.5 months vs. 67.5 months; p < .001). In detail, almost all CY+ patients among curative resection-intended cases had either elevated preoperative serum CA19-9 levels (≥250 U/mL) or DUPAN-2 levels (≥150 U/mL). Significant predictive factors of CY positivity were BR status (p = .028) and serum CA19-9 level exceeding 250 U/mL (p = .008).

CONCLUSION

CY status was identified as an independent prognostic factor, and SL examination should be recommended, especially for patients with risk factors for CY positivity, such as BR cancer and elevated serum CA19-9 levels.

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.

Artificial Intelligence-Driven Morphology-Based Enrichment of Malignant Cells from Body Fluid

Cell morphology is a fundamental feature used to evaluate patient specimens in pathologic analysis. However, traditional cytopathology analysis of patient effusion samples is limited by low tumor cell abundance coupled with the high background of nonmalignant cells, restricting the ability of downstream molecular and functional analyses to identify actionable therapeutic targets. We applied the Deepcell platform that combines microfluidic sorting, brightfield imaging, and real-time deep learning interpretations based on multidimensional morphology to enrich carcinoma cells from malignant effusions without cell staining or labels. Carcinoma cell enrichment was validated with whole genome sequencing and targeted mutation analysis, which showed a higher sensitivity for detection of tumor fractions and critical somatic variant mutations that were initially at low levels or undetectable in presort patient samples. Our study demonstrates the feasibility and added value of supplementing traditional morphology-based cytology with deep learning, multidimensional morphology analysis, and microfluidic sorting.

Cardiac tamponade

Cardiac tamponade is a medical emergency caused by the progressive accumulation of pericardial fluid (effusion), blood, pus or air in the pericardium, compressing the heart chambers and leading to haemodynamic compromise, circulatory shock, cardiac arrest and death. Pericardial diseases of any aetiology as well as complications of interventional and surgical procedures or chest trauma can cause cardiac tamponade. Tamponade can be precipitated in patients with pericardial effusion by dehydration or exposure to certain medications, particularly vasodilators or intravenous diuretics. Key clinical findings in patients with cardiac tamponade are hypotension, increased jugular venous pressure and distant heart sounds (Beck triad). Dyspnoea can progress to orthopnoea (with no rales on lung auscultation) accompanied by weakness, fatigue, tachycardia and oliguria. In tamponade caused by acute pericarditis, the patient can experience fever and typical chest pain increasing on inspiration and radiating to the trapezius ridge. Generally, cardiac tamponade is a clinical diagnosis that can be confirmed using various imaging modalities, principally echocardiography. Cardiac tamponade is preferably resolved by echocardiography-guided pericardiocentesis. In patients who have recently undergone cardiac surgery and in those with neoplastic infiltration, effusive-constrictive pericarditis, or loculated effusions, fluoroscopic guidance can increase the feasibility and safety of the procedure. Surgical management is indicated in patients with aortic dissection, chest trauma, bleeding or purulent infection that cannot be controlled percutaneously. After pericardiocentesis or pericardiotomy, NSAIDs and colchicine can be considered to prevent recurrence and effusive-constrictive pericarditis.

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.

Cytohistologic immunohistochemical correlation of epithelial tubo-ovarian neoplasms: Can cell blocks substitute for tissue?

BACKGROUND

Cytologic specimens often represent the initial diagnostic material for tubo-ovarian neoplasms resulting from therapeutic paracentesis for patients presenting with high-volume ascites. However, subtyping and immunohistochemical (IHC) characterization, which have implications in preoperative management and downstream ancillary testing, are not routinely performed in many institutions. This study aims to perform cytohistologic correlation of commonly used IHC stains to establish their reliability in peritoneal fluids/washing specimens.

METHODS

A retrospective search of the laboratory information systems was performed to identify peritoneal fluid/washing specimens involved by borderline or malignant epithelial tubo-ovarian neoplasms and concurrent/subsequent surgical resection specimens. Cell blocks and tissue were stained for PAX8, WT-1, p53, p16, Napsin-A, estrogen receptor, and progesterone receptor, and staining between cytological and surgical specimens was compared.

RESULTS

A total of 56 case pairs were included, with the following final diagnoses on histological examination: 37 high-grade serous carcinomas, eight clear cell carcinomas, one endometrioid adenocarcinoma, two low-grade serous carcinomas, and eight serous borderline tumors. There was perfect cytohistologic correlation for PAX8 (Lin's concordance correlation coefficient [LINCCC] = 1.00) and WT-1 (LINCCC = 1.00), substantial/good correlation for p53 (LINCCC = 0.96), p16 (LINCCC = 0.93), napsin-A (LINCCC = 0.91) and ER (LINCCC = 0.77), and moderate correlation for PR (LINCCC = 0.54).

CONCLUSIONS

Immunohistochemical correlation between peritoneal fluid and surgical resection specimens for tubo-ovarian neoplasms is high. Common subtypes of tubo-ovarian carcinomas can be reliably distinguished on fluids using IHC.

Pleural metastasis from pulmonary primary signet-ring squamous cell carcinoma. Case report and literature review

Signet-ring cells are morphologically defined by the presence of a large intracytoplasmic vacuole that compresses and displaces the nucleus to the periphery. In most cases, these cells are associated with adenocarcinomas of various locations, and with non-epithelial neoplasms. To date, less than 20 cases of squamous cell carcinoma with signet-ring morphology have been described, mainly located on the skin. We present the case of a 73-year-old male with pleural effusion and a left lower lobe mass. The cytological study of the pleural effusion allowed the diagnosis of metastasis of squamous cell carcinoma, signet-ring cell variant. The treatment of lung cancer in advanced stages requires a precise diagnosis that allows the best therapy to be offered to the patient, depending on the clinical stage and the positivity of the biomarkers, among others. Our patient died 18 months after the initial diagnosis.

Deep Learning-Based Classification and Targeted Gene Alteration Prediction from Pleural Effusion Cell Block Whole-Slide Images

Cytopathological examination is one of the main examinations for pleural effusion, and especially for many patients with advanced cancer, pleural effusion is the only accessible specimen for establishing a pathological diagnosis. The lack of cytopathologists and the high cost of gene detection present opportunities for the application of deep learning. In this retrospective analysis, data representing 1321 consecutive cases of pleural effusion were collected. We trained and evaluated our deep learning model based on several tasks, including the diagnosis of benign and malignant pleural effusion, the identification of the primary location of common metastatic cancer from pleural effusion, and the prediction of genetic alterations associated with targeted therapy. We achieved good results in identifying benign and malignant pleural effusions (0.932 AUC (area under the ROC curve)) and the primary location of common metastatic cancer (0.910 AUC). In addition, we analyzed ten genes related to targeted therapy in specimens and used them to train the model regarding four alteration statuses, which also yielded reasonable results (0.869 AUC for ALK fusion, 0.804 AUC for KRAS mutation, 0.644 AUC for EGFR mutation and 0.774 AUC for NONE alteration). Our research shows the feasibility and benefits of deep learning to assist in cytopathological diagnosis in clinical settings.

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

INTRODUCTION

We sought to assess the utility of the International System for Serous Fluid Cytopathology (TIS) in the context of our department's routine practice.

MATERIALS AND METHODS

We examined 1028 archived effusion cytology (pleural, peritoneal, and pericardial) cases from 2018 to 2019, and re-classified them along the international system into the following diagnostic categories: nondiagnostic (ND), negative for malignancy (NFM), atypia cells of undetermined significance (AUS), suspicious for malignancy (SFM), and malignant (MAL).

RESULTS

The full distribution of the cases examined was as follows: ND 2.0%; NFM 66.1%; AUS 6.0%; SFM 4.7%; MAL 21.2%. Overall risk of malignancy for each category was calculated as: ND 30.0%; NFM 18.0%; AUS 61.9%; SFM 100%; MAL 94.4%. The overall performance attributes of TIS were as follows: sensitivity 57.1%; specificity 98.3%; positive predictive value 94.4%; negative predictive value 82.0%; diagnostic accuracy 84.5%.

CONCLUSIONS

The new classification was simple and intuitive to use and our results appear to fall within the expected ranges of the new guidelines, with risk of malignancy and accuracy comparable to similar studies. The availability of a cell block allowed for refinement of the diagnosis in a majority of cases with equivocal cytology, though this was dependent on the cell yield.

The utility of claudin‐4 versus MOC‐31 and Ber‐EP4 in the diagnosis of metastatic carcinoma in cytology specimens

BACKGROUND

Claudin-4 is a sensitive and specific marker for carcinoma in effusion cytology. The authors examined the diagnostic use of claudin-4 versus MOC-31 and Ber-EP4 by comparing their sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in differentiating carcinoma from mesothelioma and benign/mesothelial hyperplasia in effusion specimens.

METHODS

This retrospective study comprised a cohort of 229 cytology specimens, including 211 effusion fluid and 18 fine-needle aspiration specimens. Cytologic categories included 134 carcinoma, 28 mesothelioma, 46 indefinite (suspicious and atypical), and 21 benign. Cell block sections were stained for claudin-4 and compared with those previously stained for MOC-31 and Ber-EP4. Indefinite cases were further reclassified based on clinical and pathologic findings into benign (26 cases), mesothelioma (11 cases), and carcinoma (nine cases).

RESULTS

None of the mesotheliomas (0/39) or benign effusions (0/47) were positive for claudin-4, whereas 134 of the 143 carcinoma specimens were positive. Compared to MOC-31 and Ber-EP4, claudin-4 had the highest specificity and PPV (100% for each), followed by Ber-EP4. Claudin-4 showed high sensitivity (93.7%), albeit lower than MOC-31. MOC-31 had the lowest specificity and PPV but the highest sensitivity and NPV. Ber-EP4 had the lowest sensitivity (91.6%).

CONCLUSIONS

Claudin-4 can be used as a single marker for carcinoma with high sensitivity and superior specificity compared with MOC-31 and Ber-EP4. Mesothelial lineage can be ruled out when claudin-4 is positive. In equivocal cytology samples with few scattered cells of interest, a panel of claudin-4 and Ber-EP4 results in the highest combined sensitivity and specificity.

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.

Suspicious Positive Peritoneal Cytology (Class III) in Endometrial Cancer Does Not Affect Prognosis

Positive peritoneal cytology is a poor prognostic factor in patients with advanced endometrial cancer. Suspicious positive peritoneal cytology (class III) is commonly encountered in clinical practice. However, no standard treatment protocol exists for its management. Here, we investigated a possible relationship between suspicious positive peritoneal cytology, disease stage, risk factors, and endometrial cancer prognosis. We included patients diagnosed with endometrial cancer who underwent total hysterectomy and peritoneal cytology at the University of Tokyo Hospital between 2008 and 2022. Overall, 670 patients were included in the analyses; both demographic and clinical data of the patients were collected. The proportion of patients with lymph node metastasis was significantly different between peritoneal cytology groups, showing lymph node metastasis to be more extensive in patients with positive or suspicious positive peritoneal cytology than in patients with negative peritoneal cytology (p < 0.05). Thirty-nine patients had suspicious positive peritoneal cytology. Omental resection and biopsy were performed in 16 cases. No case of omental metastasis was found. Among patients with suspected ascites cytology, no patient experienced symptom recurrence or death. Therefore, monitoring lymph node metastasis in suspicious positive cases is essential. Moreover, a change of treatment method based on the finding of suspected positive peritoneal cytology is not necessary.

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.

Malignant peritoneal cytology in endometrial cancer: a contemporary review

INTRODUCTION

: In endometrial cancer, malignant peritoneal cytology (MPC) refers to the presence of tumor cells in the peritoneal cytologic specimen obtained at hysterectomy. MPC was once a component of uterine cancer staging criteria, but it is no longer included in the current revision. Multiple societies and organizations, however, continue to recommend peritoneal cytologic testing at the time of hysterectomy for endometrial cancer.

AREAS COVERED

This contemporary review provides a clinical summary of recent studies evaluating MPC, including risk factors and prognosis. Compared to prior studies showing a lack of impact on oncologic outcome, recent studies have larger sample sizes, use stricter inclusion criteria, and perform histology/cancer stage-specific analyses to balance risk factors and provide explicit interpretations for oncologic outcomes related to MPC. These newer data provide evidence that MPC does have a prognostic impact.

EXPERT OPINION

Three key domains related to MPC are followings: First, recognition of MPC as a prognostic factor for endometrial cancer irrespective to stage (early and advanced) and histology (endometrioid and non-endometrioid) is necessary. Second, peritoneal cytologic testing at the beginning of each staging surgery is recommended. Last, incorporation of peritoneal cytology status in adjuvant treatment algorithms is useful and merits further development.

Collection and processing of effusion fluids for cytopathologic evaluation

Accumulation of fluid in serous cavities as effusions may have to be drained for therapeutic and diagnostic indications. As compared to many other procedures, the technicality of paracentesis procedures is relatively easy. As a result, effusion fluids comprise a significant proportion of specimens in most of the laboratories, including those in community settings.

Because of relative complexities in the cytopathologic evaluation of effusion fluids, application of appropriately standardized protocol is critical for achieving optimum results by applying standardized steps from handling of specimens during the initial stages of collection to the final interpretation phase. Understanding various limitations and challenges during collection and processing phases by all the personnel involved, including clinicians, pathologists, and technologists is critical for optimum diagnostic yield.

This review highlights various cytopreparatory techniques applicable to effusion cytology in one place. It is organized by projecting the details predominantly in the form of different tables and figures including summary of the recommended protocols with reagents and stains used. Also included is a sample of cytopathology report based on the approach discussed in this series.

Serous fluid: Reactive conditions

This chapter highlights the steps that would help to analyze any fluid. It highlights importance of knowing gross analysis of fluid along with biochemical information. These parameters along with clinical information are very important in arriving at a differential diagnosis. Morphologic appearances in the fluid can often become challenging and occasionally reactive conditions can reveal changes that may mimic malignancies. This chapter provides not only a framework of approach to assessment of fluid cytology but also shows how to distinguish some of the challenging reactive conditions from the diagnosis of carcinoma. The chapter also utilizes two cases to demonstrate approach to reactive conditions. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Cytopathologic Diagnosis of Serous Fluids.

Adequacy in pleural effusion: What is the minimum volume required for detection of malignant cells?

BACKGROUND

Adequacy criteria of pleural fluid volume for optimal reporting are contentious, and very little literature is available to date. This problem has not been addressed in the novel International System for Reporting Serous Fluid Cytology.

MATERIALS AND METHODS

A retrospective analysis was performed on 939 pleural fluid samples. Five volume bins were created: 0-9.9 ml, 10-19.9 ml, 20-34.9 ml, 35-69.9 ml, and > 70 ml and included 203, 222, 314, 174, and 26 samples, respectively. Volume bins were compared across various categories using a Chi-square test. A malignancy fraction was used to assess diagnostic accuracy. Descriptive statistics for categorical variables were done with median and interquartile range. A ROC curve was constructed to find if pleural fluid volume can be used to detect malignancy. A cut-off volume was found which can detect malignancy with optimum sensitivity.

RESULTS

The area under the Receiver Operating Characteristic curve showed that 55% of the time, the pleural volume can detect malignancy correctly. From the coordinates of the curve it was found that for a sensitivity of 81% and specificity of 40%, a cut-off volume of 13.5 ml of pleural fluid is sufficient to detect malignancy.

CONCLUSIONS

We recommend 13.5 ml as the minimum volume cut-off for a satisfactory pleural effusion cytology report. Below this volume, the false-negative rates increase, and the specimen may be deemed as limited for a conclusive diagnosis. As the volume rises above this threshold volume, the false negativity rate decreases but does not significantly improve malignant cells' detection.

Primary and metastatic peritoneal surface malignancies

Peritoneal surface malignancies comprise a heterogeneous group of primary tumours, including peritoneal mesothelioma, and peritoneal metastases of other tumours, including ovarian, gastric, colorectal, appendicular or pancreatic cancers. The pathophysiology of peritoneal malignancy is complex and not fully understood. The two main hypotheses are the transformation of mesothelial cells (peritoneal primary tumour) and shedding of cells from a primary tumour with implantation of cells in the peritoneal cavity (peritoneal metastasis). Diagnosis is challenging and often requires modern imaging and interventional techniques, including surgical exploration. In the past decade, new treatments and multimodal strategies helped to improve patient survival and quality of life and the premise that peritoneal malignancies are fatal diseases has been dismissed as management strategies, including complete cytoreductive surgery embedded in perioperative systemic chemotherapy, can provide cure in selected patients. Furthermore, intraperitoneal chemotherapy has become an important part of combination treatments. Improving locoregional treatment delivery to enhance penetration to tumour nodules and reduce systemic uptake is one of the most active research areas. The current main challenges involve not only offering the best treatment option and developing intraperitoneal therapies that are equivalent to current systemic therapies but also defining the optimal treatment sequence according to primary tumour, disease extent and patient preferences. New imaging modalities, less invasive surgery, nanomedicines and targeted therapies are the basis for a new era of intraperitoneal therapy and are beginning to show encouraging outcomes.

Clinico-cytopathologic analysis of 574 Pericardial Effusion Specimens: Application of the international system for reporting serous fluid cytopathology (ISRSFC) and long-term clinical follow-up

INTRODUCTION

A pericardial effusion (PE) has a variable etiology and the primary role is diagnosis of metastatic malignancy. We analyzed the PE cytology in a large cohort in accordance with the international system for reporting serous fluid cytopathology (ISRSFC) and evaluated the long-term patient outcomes.

METHODS

PE specimens from 2010 to 2014 with an available clinical history, cytologic data, and pericardial biopsy results were collected.

RESULTS

A total of 574 PE specimens were obtained from 486 patients, representing 1.5% (574/38,589) of all body fluid specimens. Three hundred and eighty-two (66.6%) cases were "negative," 54 (9.4%) cases were "atypia of undetermined significance," 10 (1.7%) cases were "suspicious for malignancy," and 128 (22.3%) cases were "malignancy". The most common origin for malignant PE was the lung (82.1%), in both men (70.5%) and women (50.6%). Breast cancer (20%) in women and gastric cancer (4.9%) in men were the second most common malignant PE, respectively. The mean interval from the occurrence of malignant PE to death was 10.06 months (range; 0-116.03 months, median 3.5 months), and the 1-year survival rate was 16.7%. In addition, the 1-year survival rates after malignant PE onset were 0% for gastric cancer, 13.9% for lung cancer, 19.8% for breast cancer, and 21.1% for the other cancers (p = 0.011).

CONCLUSION

Our present study is the first to our knowledge to classify the pericardial fluid from 574 cases in accordance with the recently published ISRSFC, and to present the long-term outcomes of patients with malignant PE at the same time. Moreover, we report for the first time that it is gastric and not lung cancer patients that have the poorest prognosis after the occurrence of malignant PE.

Leptomeningeal Carcinomatosis: A Call for Optimizing Diagnostic Sensitivity by the Hematology Laboratory

In the cerebrospinal fluid (CSF), the demonstration of malignant cells by cytological examination is currently the gold standard for the diagnosis of leptomeningeal carcinomatosis (LC). However, a positive cytology is observed in only 50–60% of patients with LC and highly dependent on pre-analytical factors. The hematology laboratory could provide an immediate and accurate diagnosis, but diagnostic sensitivity is not always optimized once the sample is received. We hereby report a 49-year-old woman with a 3-year grade III invasive ductal carcinoma who was admitted to the emergency department due to headaches, nausea, and vomiting. The CSF revealed pleocytosis with suspicious high fluorescent cells on the hematology analyzer concomitantly with biochemical alterations. Cytomorphological examination confirmed tumor cells, thus diagnosing a leptomeningeal metastasis of her breast cancer. The patient was eventually transferred to palliative care. Cytological examination is a valuable tool for a rapid diagnosis of LC if diagnostic performance is optimized. In addition to repeated CSF collections with a sufficient volume (5–10 mL), this could be reached by processing the CSF as soon as possible, taking into account the fluorescence information from the analyzer, proceeding systematically to microscopic examination even with normal CSF white blood cell count, and providing quality improvement of the staff to identify malignant cells.

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.

State-of-the-art cytology of pleural fluid, focusing on the diagnosis of mesothelioma

Mesothelioma has always been a challenging diagnosis to render in body cavity cytology samples. This review is a timely update on pleural fluid cytology and ancillary studies that should be considered in the diagnosis of mesothelial proliferations, specifically mesotheliomas. Information about new diagnostic approaches and ancillary studies in mesothelioma was obtained from the peer-reviewed literature and the authors' experiences. Although the morphological diagnosis of mesothelioma is fraught with numerous challenges given the overlap with other diagnostic entities, there are a variety of immunohistochemical and fluorescence in situ hybridization studies available to help in determining mesothelial origin and in distinguishing malignant proliferations from the more common benign or reactive mesothelial proliferations. Although ancillary studies can be helpful, there are important pitfalls to be aware of when interpreting these cases, and this review highlights some of the challenges that require caution.

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.