A minimum fluid volume of 75 mL is needed to ensure adequacy in a pleural effusion: a retrospective analysis of 2540 cases

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.

Exploratory pilot study to characterize the immune landscapes of malignant pleural effusions and their corresponding primary tumors from patients with breast carcinoma and lung adenocarcinoma

INTRODUCTION

Malignant pleural effusion (MPE) is a frequent complication of advanced malignancies. In this pilot study, we characterized the immune landscapes of MPEs, compared them to their primary tumor (PT) samples from breast carcinoma (BC) and lung adenocarcinoma (LADC), and tested the utility of multiplexed image technology in cytological samples.

MATERIALS AND METHODS

We evaluated the immune contexture of 6 BC and 5 LADC MPEs and their PTs using 3 multiplex immunofluorescence panels. We explored the associations between sample characteristics and pleural effusion-free survival.

RESULTS

No MPE samples had positive programmed death-ligand 1 expression in malignant cells, although 3 of 11 PTs has positive programmed death-ligand 1 expression (more than 1% expression in malignant cells). Overall, in LADC samples, cluster of differentiation 3 (CD3)+ T cells and CD3+CD8+ cytotoxic T cells predominated (median percentages for MPEs versus PTs: 45.6% versus 40.7% and 4.7% versus 6.6%, respectively) compared with BC. CD68+ macrophages predominated in the BC samples (medians for MPEs 61.2% versus PTs for 57.1%) but not in the LADC samples. Generally in PTs, CD3+CD8+ forkhead box P3+ T cells and the median distances from the malignant cells to CD3+CD8+Ki67+ and CD3+ programmed cell death protein 1 + T cells correlated to earlier MPE after PT diagnosis.

CONCLUSIONS

The immune cell phenotypes in the MPEs and PTs were similar within each cancer type but different between BC versus LADC. An MPE analysis can potentially be used as a substitute for a PT analysis, but an expanded study of this topic is essential.

Second opinion for pulmonary and pleural cytology is valuable for patient care

INTRODUCTION

Thoracic cytology can be challenging due to limited procured material or overlapping morphology between benign and malignant entities. In such cases, expert consultation might be sought. This study aimed to characterize all pulmonary and pleural cytology consult cases submitted to our practice and provide recommendations on approaching difficult cases.

MATERIALS AND METHODS

All thoracic (pulmonary and pleural) cytology cases submitted for expert consultation to the University of Michigan (MLabs) from 2013 to mid-2022 were reviewed. Cases where cytology was only part of a hematopathology or surgical pathology consult were excluded. Patient demographics, specimen location, procedure performed, referring diagnosis, and our diagnoses were recorded for each case. Diagnoses were categorized according to the Papanicolaou Society of Cytopathology recommendations for pulmonary and effusion cytology. Discordant diagnoses were stratified as major or minor. Data was analyzed using chi-square analysis and logistic models.

RESULTS

We received 784 thoracic cytology consult cases, including 530 exfoliative samples and 307 fine-needle aspirations. The most common anatomic locations sampled were the bronchial wall (n = 194, 23%), lung nodule (n = 322, 38%), and pleura (n = 296, 35%). 413 cases had a diagnostic discrepancy (48.3%), with 274 (66%) minor and 139 (34%) major discrepancies. By location, pleural effusion specimens had the highest probability of a discrepant diagnosis (P = 0.003). By specimen type, fine-needle aspiration samples were significantly more likely to have a discrepant diagnosis (P = 0.06).

CONCLUSION

Nearly half of the thoracic cytology cases submitted for expert second opinion had diagnostic discrepancies. Consequently, consulting a tertiary medical care center with cytopathology expertise for challenging thoracic cytology diagnoses is beneficial.

Optimal Volume Assessment for Serous Fluid Cytology

OBJECTIVE

This study aimed to investigate the optimal volume of serous fluid needed for accurate diagnosis using The International System for Reporting Serous Fluid Cytopathology (TIS), as well as to provide information on the distribution of serous effusion cases in the TIS categories (ND: non-diagnostic, NFM: negative for malignancy, AUS: atypia of undetermined significance, SFM: suspicious for malignancy, MAL: malignant) and relevant epidemiological data.

METHODS

A retrospective analysis of 2340 serous effusion cases (pleural, peritoneal, and pericardial) from two hospitals between 2018 and 2020 was conducted. TIS categories were assigned to each case, and for 1181 cases, these were correlated with the volume of the analyzed fluid.

RESULTS

Our study found statistically significant differences in volume distributions between certain TIS categories. Statistically lower volumes were observed in NFM compared to MAL, in UNCERTAIN (ND, AUS, SFM) compared to both MAL and NFM, and in NOT MAL (ND, NFM, AUS, SFM) compared to MAL. However, these differences were not substantial enough to hold any clinical relevance.

CONCLUSIONS

This study suggests that while fluid volume may slightly influence the TIS category, it does not impact the diagnostic accuracy of serous effusion cytology. Therefore, the ideal serous effusion specimen volume can be defined solely by practical parameters.

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.

Malignant pleural effusion: current understanding and therapeutic approach

Malignant pleural effusion (MPE) is a common complication of thoracic and extrathoracic malignancies and is associated with high mortality and elevated costs to healthcare systems. Over the last decades the understanding of pathophysiology mechanisms, diagnostic techniques and optimal treatment intervention in MPE have been greatly advanced by recent high-quality research, leading to an ever less invasive diagnostic approach and more personalized management. Despite a number of management options, including talc pleurodesis, indwelling pleural catheters and combinations of the two, treatment for MPE remains symptom directed and centered around drainage strategy. In the next future, because of a better understanding of underlying tumor biology together with more sensitive molecular diagnostic techniques, it is likely that combined diagnostic and therapeutic procedures allowing near total outpatient management of MPE will become popular. This article provides a review of the current advances, new discoveries and future directions in the pathophysiology, diagnosis and management of MPE.

Malignant pleural disease

Malignant pleural disease represents a growing healthcare burden. Malignant pleural effusion affects approximately 1 million people globally per year, causes disabling breathlessness and indicates a shortened life expectancy. Timely diagnosis is imperative to relieve symptoms and optimise quality of life, and should give consideration to individual patient factors. This review aims to provide an overview of epidemiology, pathogenesis and suggested diagnostic pathways in malignant pleural disease, to outline management options for malignant pleural effusion and malignant pleural mesothelioma, highlighting the need for a holistic approach, and to discuss potential challenges including non-expandable lung and septated effusions.

Optimal fluid volume for detecting malignancy in serous effusions: a single institution experience

INTRODUCTION

Detection of malignant cells in serous fluids is an indicator of advanced stage of malignancy and is critical in clinical management decisions and prompt treatment initiation. The minimum volume which is ideal for detecting malignancy in serous fluid is not well established. In this study, we aim to identify optimal volume that will be ideal for adequate cytopathological diagnosis.

MATERIALS AND METHODS

A total of 1597 samples of serous fluids from 1134 patients were included in the study. Samples were diagnosed based on International System for Reporting Serous Fluid Cytopathology (ISRSFC). Clinicopathologic results from different diagnostic groups were compared and statistically analyzed.

RESULTS

Pleural fluids comprised 890 (55.7%) specimens, followed by 456 (28.6%) peritoneal, 128 (8%) ascites, and 123 (7.7%) pericardial fluid specimens. The majority were negative for malignancy (1138, 71.3%), followed by malignant (376, 23.5%), atypical (59, 3.7%), and suspicious for malignancy (24, 1.5%). Malignancy was identified in sample with volumes from 5 mL to 5000 mL. Rate of detection of malignant cells increased significantly with higher sample volumes. For malignancy detection the optimal volume for overall serous fluid is 70 mL. Pericardial fluid is an exception, with lower mean volume and significantly lower proportion of cases with malignant diagnosis.

CONCLUSIONS

Our study indicates that higher fluid volumes have a higher rate of malignancy detection and a low false-negative rate. We recommend a minimum of 70 mL of serous fluid for optimal cytopathologic examination and malignancy detection. Pericardial fluid is an exception, with lower mean volume and thus lower requirement.

The international system for reporting serous fluid cytopathology: The initial project survey

OBJECTIVE

An international panel in the field of body fluid cytology, supported by the International Academy of Cytology and the American Society of Cytopathology, conducted a survey to identify opinions and explore existing practice patterns regarding body fluid cytopathology.

METHODS

The study group, formed during the 2018 European Congress of Cytology in Madrid, generated a survey of 54 questions related to the practice and taxonomy of body fluid cytology. The survey was available online from 28 August 2018 until 10 December 2018. Participants were invited through the websites and listserves of the professional societies.

RESULTS

The survey collected 593 international participant responses. Questions pertained to practice patterns and diagnostic language. Information was collected regarding credentials, work setting, work volume (4-10,000 samples) and years in practice (0-60 years). The responses revealed variations in diagnostic practice and sample management. Direct smears and ThinPrep® preparations are the most popular methods, followed by Cytospin® and SurePath®. Most (70%) respondents perform ancillary studies on their material, with over 50% preferring a cell block preparation. Approximately 32% indicated that they are capable of performing genetic studies on the samples. Nearly 78% of participants would accept a two-stage cytology report, with a preliminary assessment followed by a final diagnosis that accounts for ancillary studies to generate a more precise cytological interpretation. Approximately one-third (36%) never report adequacy on body fluid samples. Most (78%) report a general category result (negative, atypical, suspicious, or positive) and 22% provide a detailed surgical pathology type report. Most (73.6%) participants believe that both Papanicolaou stains and a modified Giemsa stain (eg Diff Quik) should be standard preparations for all serous fluid cytology.

CONCLUSIONS

The results of the survey demonstrated strong support for the development of a unified system for reporting body fluid cytopathology among respondents.

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.

Malignant Pleural Effusions: Updates in Diagnosis and Management

Malignant pleural effusions remain a significant clinical problem resulting in greater than 125,000 hospitalizations per year and leading to over 5 billion dollars in healthcare utilization costs. Not only are health care expenditures related to malignant pleural effusion significant, but malignant pleural effusions also often result in significant patient discomfort and distress, largely at the end of life. Advances in management over the past several years have provided patients with greater autonomy as they are able to provide self-aid at home either alone or with family assistance. Additionally, practice changes have allowed for fewer interventions allowing patients to spend more time out of the clinic or inpatient wards.

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.

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.

[Cytopathology and molecular diagnostics of non-small cell lung cancer (NSCLC)]

Cytological specimens from endobronchial aspirates and pleural effusions are frequently used materials in the diagnostics of non-small cell lung cancer (NSCLC). In the same way as histological samples from endobronchial and transbronchial biopsy material or computed tomography (CT)-guided needle biopsies, cytological specimens are eminently suitable for molecular and immunohistological biomarker diagnostics of NSCLC, provided optimal techniques and clear diagnostic algorithms are employed. This article presents the typical processing techniques and a scheme for biomarker analytics and discusses an optimal approach for comprehensive diagnostics of NSCLC. When cytological specimens are processed and used in this way, the analytics are equivalent to those from histopathological specimens. For a detailed and advanced description of cytological and molecular techniques on cytological specimens the reader is referred to our own review articles.

Malignant pleural disease: a pragmatic guide to diagnosis

PURPOSE OF REVIEW

The diagnosis of malignant pleural disease is important in the care of patients with cancer. However, a one-size-fits-all approach to diagnosis may lead to delays in care as the sensitivity of each biopsy modality varies and can be dependent on the tumor type. We review current literature on pleural biopsy techniques and propose a diagnostic algorithm for suspected malignant pleural disease.

RECENT FINDINGS

Recent literature has shown that the sensitivity of pleural fluid cytology varies based on tumor type resulting in a limited value of repeated thoracenteses in many cases. Furthermore, the ability to test for molecular biomarkers on pleural fluid samples has contributed to the recommendations to send large volumes of pleural fluid for analysis. Studies have also supported the consideration of medical thoracoscopy earlier in the diagnostic work-up of malignant pleural disease.

SUMMARY

The decision to repeat a diagnostic thoracentesis when suspecting malignant pleural effusions should take into account the primary tumor type. Open pleural biopsy with medical thoracoscopy has been shown to be a relatively safe diagnostic modality with high sensitivity and should be considered in patients with a nondiagnostic thoracentesis.

Reassessing the optimal volume for malignancy detection in serous fluid cytology

BACKGROUND

The international system for reporting serous fluid cytopathology (TIS) recommends submitting at least 50-75 mL of serous fluid to decrease false-negative results. However, prior studies did not agree on specific volume requirements or consensus adequacy criteria. Our study aims to assess whether fluid volume affects the adequacy rate and to assess the minimum volume necessary for optimal adequacy in pleural and peritoneal fluids.

METHODS

A total of 8530 serous fluid cytology cases were identified in the laboratory information system. Differences in mean fluid volume received in the laboratory were compared using an ANOVA Games-Howell test based on TIS category. The percentage of malignant diagnoses across the volume ranges of 0 to 5 mL, 5 to 10 mL, 10 to 25 mL, 25 to 50 mL, 50 to 75 mL, 75 to 100 mL, 100 to 150 mL, 150 to 250 mL, 250 to 500 mL, 500 to 2000 mL was compared in pleural and peritoneal fluids using a chi-square test, and a SiZer analysis was performed.

RESULTS

Mean fluid volume in inadequate, atypical, and negative cases was significantly lower compared to positive cases. A SiZer analysis showed a positive relationship between the malignancy fraction of pleural and peritoneal fluids and fluid volume. The percentage of malignant diagnoses in pleural and peritoneal fluid samples increased significantly up to a volume range of 75-100 mL.

CONCLUSIONS

There is a significant relationship between fluid volume, adequacy and detection of malignancy in serous effusion cytopathology. The malignancy fraction increases with larger fluid volumes but at least 75-100 mL of fluid should be submitted for optimal diagnosis of malignancy in pleural and peritoneal fluids.

Diagnosis and Management of Malignant Pleural Effusion: A Decade in Review

Malignant pleural effusion (MPE) is a common complication of thoracic and extrathoracic malignancies and is associated with high mortality. Treatment is mainly palliative, with symptomatic management achieved via effusion drainage and pleurodesis. Pleurodesis may be hastened by administering a sclerosing agent through a thoracostomy tube, thoracoscopy, or an indwelling pleural catheter (IPC). Over the last decade, several randomized controlled studies shaped the current management of MPE in favor of an outpatient-based approach with a notable increase in IPC usage. Patient preferences remain essential in choosing optimal therapy, especially when the lung is expandable. In this article, we reviewed the last 10 to 15 years of MPE literature with a particular focus on the diagnosis and evolving management.

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.

[Cytology of body cavity fluids - established methods and new developments]

BACKGROUND

Body cavity fluids are among the most frequently examined samples in cytology. Cytomorphology is supplemented by additive testing. An international system of terminology and classification has been recently presented.

OBJECTIVES

Cytopreparation and staining techniques as well as some exemplary morphological patterns are presented. "The International System for Serous Fluid Cytopathology" (TIS) is briefly presented.

MATERIALS AND METHODS

Pleural effusion, pericardial effusion, and ascites: special technical issues, immunocytochemistry, molecular diagnostics, and reporting system issues are discussed.

RESULTS

Body cavity fluids are important samples that provide significant information. Additive testing is established for routine use. The form and structure of reports is widely divergent in practical use.

DISCUSSION

A reporting system for serous fluid cytopathology that is easily applied and recognized internationally is highly desirable. TIS is a valuable approach to this goal.

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.

Adequacy of pleural fluid cytology for comprehensive molecular analysis of lung adenocarcinoma: Experience of a large health-care system

Objectives:

Pleural fluid evaluation is an effective modality for identifying actionable genetic mutations to guide therapy in lung carcinoma. Clinicians requesting molecular studies often send large volumes of fluid to be processed that is not possible or cost effective and is hence not standard of practice in most cytopathology laboratories. We wanted to establish the characteristics of an adequate specimen that would yield reliable results with current molecular testing platforms.

Material and Methods:

A review of 500 malignant pleural effusions, from pulmonary and non-pulmonary sources, was undertaken over a 4-year period. Of these 44 cases (from 42 patients) that were positive for primary lung adenocarcinoma were included in the study. Molecular analysis was performed on 42 specimens. A complete next generation sequencing (NGS) panel was performed on 36 specimens. Individual testing for estimated glomerular filtration rate, KRAS, anaplastic lymphoma kinase, and ROS1 was performed on six specimens. The number of malignant cells and proportion of tumor to non-tumor nucleated cells (T: NT) on cell blocks was recorded as <20%, 20–50% and >50%.

Results:

The minimum volume on which a complete NGS panel could be performed was 20 ml with cell count of 1000 and T: NT proportion of 20–50%. The minimum number of tumor cells required for successful molecular analysis for T: NT proportion of <20%, 20–50%, and >50% was 300, 250, and 170 cells, respectively.

Conclusion:

We concluded that tumor cell proportion, rather than specimen volume, is of prime importance for determining the efficacy of pleural fluid for molecular studies. Evaluation of both absolute and relative numbers of tumor cells is critical for assessing the adequacy and predicting successful yield for molecular analysis.

Application of the Indian academy of cytologists recommendations for reporting serous fluid cytopathology in routine reporting of ascitic fluid specimen and assessment of the risk of malignancy

Background:

A five-tiered reporting system for effusion fluid cytology has been published by the Indian Academy of Cytologists (IAC). Only a single study has evaluated the applicability of this system in routine reporting.

Aims:

We intend to evaluate the practical utility of this system in routine reporting of ascitic fluid cytology.

Materials And Methods:

Nine hundred and sixty-one cases of ascitic fluid cytology were included in this study. The clinical, radiological, cytomorphological, and follow-up data of these cases were reviewed. All cases were recategorized according to the proposed IAC system, and the risk of malignancy (ROM) for each category was estimated.

Results:

Age of the patients ranged from 1 to 92 years, and fluid volume ranged from 10 ml to 3 l. The number of cases included in each category and their respective ROM were as follows: category 1: 41, 21.42%; category 2: 805, 14.9%; category 3: 5, 33.3%; category 4: 31, 90%; and category 5:79, 96.4%.

Conclusions:

The new IAC guidelines for the serous fluid is representative, informative, and could be easily applied at our institutional level. We used the recommended diagnostic categories for reclassifying the ascitic fluid samples based on their cytosmear findings and conclude that the system has enormous utility at each level starting from the collection of fluid samples till the delivery of the report.

How much is enough: investigation of pleural fluid cytology findings related to sample volume

INTRODUCTION

Cytologic evaluation of pleural effusion samples plays an invaluable role in patient care. Despite this, only a few robust studies have investigated the optimal specimen volume for cytologic evaluation. It is not unusual for our laboratory to receive low-volume pleural effusion samples. Thus, as a part of ongoing quality assurance studies, we examined the performance of low-volume samples.

MATERIALS AND METHODS

All pleural effusion samples received during a 1-year period from January 1, 2020 to December 31, 2020 were reviewed. The case data collected included the clinical indications, diagnostic categorization, cell block performance, and adequacy notations. Follow-up data were also collected. The cases were placed into low-volume (≤10 mL, 11-25 mL, and 26-50 mL) and higher volume (>50 mL) groups for analysis.

RESULTS

A total of 226 samples were included in the present study. Of the 226 samples, 89 had a volume of ≤50 mL, including 32 with a very low volume of ≤10 mL. Significantly fewer positive cases were diagnosed in the ≤10-mL group relative to the >50-mL group (6.3% versus 27.7%) with significantly fewer cell blocks performed (15.6% versus 57.7%). However, only 7 of the ≤10 mL cases (21.9%) had been performed to rule out malignancy, significantly less than that for the >50 mL group (81 of 137; 59.1%). Additionally, none of the very-low-volume cases had an upgraded follow-up effusion sample.

CONCLUSIONS

The exact role of the sample volume is not entirely clear as there are many factors are at play beyond volume itself. Although larger specimen volumes might be more optimal for a number of reasons, malignancy can be diagnosed at even low sample volumes. Thus, there is value to examining all samples regardless of the volume received. Insertion of an adequacy comment might be prudent for low-volume cases, especially those with a high clinical concern for malignancy.

Modern day management of a unilateral pleural effusion

Over 50 systemic conditions may affect the pleura and, thus, unilateral pleural effusions may present for a variety of reasons. Investigating the cause is essential to providing appropriate management. Various pleural interventions are available in current practice, but have varying diagnostic sensitivity. It is, therefore, vital to consider the intervention with the highest diagnostic yield appropriate to the particular clinical situation. The diagnostic pathway in unilateral pleural effusion is increasingly outpatient based, avoiding hospitalisation, which is particularly relevant with the recent COVID-19 pandemic.

Technical aspects of the use of cytopathological specimens for diagnosis and predictive testing in malignant epithelial neoplasms of the lung

Lung cancer is a leading cause of cancer mortality worldwide but recent years have seen a rapidly rising proportion of cases of advanced non-small cell carcinoma amenable to increasingly targeted therapy, initially based on the differential response to systemic treatment of tumours of squamous or glandular differentiation. In two-thirds of the cases, where patients present with advanced disease, both primary pathological diagnosis and biomarker testing is based on small biopsies and cytopathological specimens. The framework of this article is an overview of the technical aspect of each stage of the specimen pathway with emphasis on maximising potential for success when using small cytology samples. It brings together the current literature addressing pre-analytical and analytical aspects of specimen acquisition, performing rapid onsite evaluation, and undertaking diagnostic and predictive testing using immunocytochemistry and molecular platforms. The advantages and drawbacks of performing analysis on cell block and non-cell block specimen preparations is discussed.

Cytologic Investigations for the Diagnosis of Malignant Pleural Effusion in Non-small Cell Lung Cancer: State-of-the-art Review for Pulmonologists

Lung cancer is the current leading cause of cancer-related deaths worldwide, and malignant pleural effusion, an indicator of the advanced stage of this disease, portends a poor prognosis. Thus, making an accurate diagnosis of malignant pleural effusion is of paramount importance. During the past decade, the prognosis of patients with advanced non-small cell lung cancer has improved substantially, especially in those treated with targeted therapy and immunotherapy. The use of pleural fluid cytology should not only provide diagnoses but also aid in the selection of targeted therapies, especially when obtaining a histologic specimen is too difficult. In this evidence-based review, we address the importance of pleural fluid cytology in non-small cell lung cancer patients, from making the diagnosis to making treatment-related decisions when only pleural fluid is available.

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.

The value of cytology in distinguishing malignant mesothelioma: An institutional experience of 210 cases reclassified according to the International System for Reporting Serous Fluid Cytopathology (ISRSFC)

OBJECTIVE

Malignant mesothelioma (MM) is usually diagnosed by histological examination of tissue samples; however, effusion cytology offers an opportunity to identify a strong possibility for mesothelioma diagnosis at an early stage. We conducted a retrospective analysis of cytological specimens from a large series of histologically proven MM diagnosed over 19 years. The cases were reviewed and reclassified according to the International System for Reporting Serous Fluid Cytopathology (ISRSFC).

METHODS

A total of 450 cases were identified. Cytological analysis was present in 210 patients (164 pleural and 46 peritoneal effusions). All cases were reviewed and reclassified according to the proposed ISRSFC scheme. A comparison among the cytomorphological features was made throughout the different diagnostic categories.

RESULTS

The 210 cases were histologically diagnosed as follows: 192 (91.4%) cases had an epithelioid type and 18 (8.6%) had a sarcomatoid subtype of MM. The cytological cases were reclassified as follows: 2 (0.9%) as non-diagnostic (ND), 81 (38.6%) as negative for malignancy (NFM), 4 (1.9%) as atypia of undetermined significance (AUS), 11 (5.2%) as suspicious for malignancy (SFM), 112 (53.4%) as malignant (MAL). Sarcomatoid cells in the MAL category were characterised cytomorphologically by more pronounced discohesion. In comparison with the epithelioid subtype, the tumour cells appeared solitary with moderate or marked nuclear pleomorphism, and irregular chromatin.

CONCLUSIONS

It is important to recognise the cytological characteristics of this aggressive entity to suggest an early and precise possible diagnosis. Morphological features, coupled with clinico-radiological data may help the clinicians in adequately managing the patients.

The International System for Reporting Serous Fluid Cytopathology: How to Incorporate Molecular Data in Cytopathology Reports

Serous effusion cytology is widely employed in the initial evaluation of the etiology of effusions with a high diagnostic sensitivity. To standardize practices, The International System for Reporting Serous Fluid Cytology (TIS) was developed following best international practices, the most up-to-date literature, and expert consensus. In the context of this system, ancillary techniques play an important role. Besides defining basic principles in laboratory specimen handling, adequacy criteria, and a standardized reporting terminology with five diagnostic categories, TIS provides an actionable framework for using immunohistochemical and molecular testing in effusion samples, namely, in atypical, suspicious of malignant samples. For diagnostic purposes, these tests may be employed to distinguish between a primary and secondary neoplasm, to confirm a diagnosis of malignant mesothelioma vs. reactive mesothelial hyperplasia, and to correctly classify and determine the primary location of a metastasis. Theranostic molecular tests may also be used for these samples to evaluate potential therapeutic targets. Pathologists play a central role in guiding this process by determining adequacy and selecting appropriate ancillary tests. The activity in this area of research should increase in the near future as new therapeutic targets are discovered and new drugs enter the clinical practice.

Serous fluid cytopathology: Past, present, and future

Serous fluids/effusions are common cytology samples that reflect a wide range of diseases and lend themselves to a multitude of investigations that include microscopy, chemical analysis, cell count, cultures, and analysis for biomarkers and immunomarkers. In recent years, effusions have also served as a liquid biopsy that can be interrogated by molecular tests for thoranostic and prognostic markers and selection of targeted therapy. The recently published International Reporting System for Serous Fluid Cytopathology (IRSSF) provides a standardized reporting terminology with well- defined diagnostic criteria. This editorial provides a global review of the progress in the work-up of effusions and a summary of the IRSSF book and its most significant contributions. The editorial also includes a summary of the diagnostic categories including their definition and the significant relevant information.

Diagnostic mesothelioma biomarkers in effusion cytology

Malignant mesothelioma is a rare malignancy with a poor prognosis whose development is related to asbestos fiber exposure. An increasing role of genetic predisposition has been recognized recently. Pleural biopsy is the gold standard for diagnosis, in which the identification of pleural invasion by atypical mesothelial cell is a major criterion. Pleural effusion is usually the first sign of disease; therefore, a cytological specimen is often the initial or the only specimen available for diagnosis. Given that reactive mesothelial cells may show marked atypia, the diagnosis of mesothelioma on cytomorphology alone is challenging. Accordingly, cell block preparation is encouraged, as it permits immunohistochemical staining. Traditional markers of mesothelioma such as glucose transporter 1 (GLUT1) and insulin-like growth factor 2 mRNA-binding protein 3 (IMP3) are informative, but difficult to interpret when reactive proliferations aberrantly stain positive. BRCA1-associated protein 1 (BAP1) nuclear staining loss is highly specific for mesothelioma, but sensitivity is low in sarcomatoid tumors. Cyclin-dependent kinase inhibitor 2A (CDKN2A)/p16 homozygous deletion, assessed by fluorescence in situ hybridization, is more specific for mesothelioma with better sensitivity, even in the sarcomatoid variant. The surrogate marker methylthioadenosine phosphorylase (MTAP) has been found to demonstrate excellent diagnostic correlation with p16. The purpose of this review is to provide an essential appraisal of the literature regarding the diagnostic value of many of these emerging biomarkers for malignant mesothelioma in effusion cytology.

Diagnostics in Pleural Disease

Pleural disease diagnostics represent a sprawling topic that has enjoyed a renaissance in recent years from humble beginnings. Whilst pleural patients are heterogeneous as a population and in the aetiology of the disease with which they present, we provide an overview of the typical diagnostic approach. Pleural fluid analysis is the cornerstone of the diagnostic pathway; however, it has many shortcomings. Strong cases have been made for more invasive upfront investigations, including image-guided biopsies or local anaesthetic thoracoscopy, in selected populations. Imaging can guide the diagnostic process as well as act as a vehicle to facilitate therapies, and this is never truer than with the recent advances in thoracic ultrasound.

Root cause analysis of indeterminate diagnoses in serous fluids cytopathology

INTRODUCTION

The International System for Reporting Serous Fluid Cytopathology proposed five diagnostic categories: Nondiagnostic (ND), Negative for Malignancy (NFM), Atypia of Undetermined Significance (AUS), Suspicious for Malignancy (SFM) and Malignant (MAL) (Primary or Metastatic). The indeterminate (AUS/SFM) categories are challenging for management. The goal of this study is to reveal the root causes contributing to indeterminate diagnoses (ID).

MATERIALS AND METHODS

We searched our archives between 1 January 2017 and 30 June 2019, and performed a root cause analysis (RCA) using the "5 whys" method to determine the contributing factors of ID.

RESULTS

Nine hundred eleven specimens were evaluated and diagnosed: ND (9, 1%), NFM (667, 73.2%), AUS (51, 5.6%), SFM (27, 3%) and MAL (157, 17.2%). More than one factor contributed to 38/78 ID. Low volume (<50 cc), and low cellularity were identified in 31 and 51 cases, respectively. Three cases were simply deferred to concurrent biopsy. Eleven cases were called atypical, favor reactive mesothelium despite confirmatory IHC. Atypical lymphoid population was reported in seven cases. Cellblocks (CB) were low in cellularity despite volume >1000 mL in 13 cases. Two mesotheliomas were underdiagnosed as suspicious.

CONCLUSIONS

Low cellularity and low volume were the most common contributing factors, highlighting the importance of adequate sample collection. Adequate volume specimens with low cellularity may benefit from a close inspection and a second CB. Some IDs can be switched to NFM or MAL with careful consideration of clinical, radiologic findings and ancillary testing, and concurrent surgical pathology correlation when available.

Contemporary Approach to the Diagnosis of Malignant Pleural Effusion

Advanced malignancy is a prevalent cause of exudative pleural effusion. The management of malignant pleural effusion (MPE) has been the subject of several recent randomized controlled trials and excellent reviews. Less attention has been focused on another controversial and challenging aspect of MPE: establishing the diagnosis. Before selecting the optimal management strategy, the presence of an MPE must first be correctly identified with an emphasis on minimizing invasiveness and discomfort in a patient with late-stage cancer. The aim of the present review is to summarize the current knowledge about MPE diagnostics and to propose an algorithm for the diagnosis of MPE in established or suspected malignancy.

Suspicious for Malignancy Diagnoses on Pleural Effusion Cytology

OBJECTIVES

A definitive diagnosis of malignancy may not be possible in pleural effusions. We report our experience with the diagnosis of suspicious for malignancy (SFM) in pleural effusion.

METHODS

A search for pleural effusions diagnosed as SFM (2008-2018) was performed. Patient records and pathology reports were reviewed. Specimens were subdivided into groups depending on volume (<75, 75-400, >400 mL). Diagnoses of malignant pleural effusion (MPE) served as controls.

RESULTS

We identified 90 patients, with a mean age of 60.6 years. Diagnoses included suspicious for involvement by carcinoma/adenocarcinoma in 64.4%, leukemia/lymphoma in 15.6%, melanoma in 2.2%, sarcoma in 3.3%, germ cell tumor in 1.1%, and not otherwise specified in 13.3%. Immunostains were performed in 47.8% and considered inconclusive in 24%. Average sample volume was 419 mL. There was a statistically significant difference between the SFM vs MPE groups for volumes greater than 75 mL (P = .001, χ 2 test), with SFM having increased proportion of volumes  greater than 400 mL, compared with the MPE group. There was no statistically significant difference in mean overall survival when the groups were compared (P = .49).

CONCLUSIONS

Samples with low cellularity, scant cell blocks, and inconclusive immunostains may contribute to a suspicious category diagnosis in pleural effusions.

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

INTRODUCTION

Effusions can develop inside serous cavities in several pathologic states, both neoplastic and non-neoplastic. They are easy to drain and can provide useful diagnostic information. However, the reported diagnostic efficacy of these specimens has not been uniform across different laboratories. To standardize practices, the international system for reporting serous fluid cytology (TIS) was developed in accordance with the best international practices, the most up-to-date reported data, and expert consensus.

RESULTS

TIS has set the basic principles for laboratory handling of serous effusion specimens, defined the adequacy criteria, and set a standardized reporting terminology with well-defined criteria for each diagnostic category. These include nondiagnostic, negative for malignancy, atypia of undetermined significance, suspicious for malignancy, and malignant. Each can provide useful inherent information for appropriate clinical management and follow-up, with a defined expected diagnostic category incidence and risk of malignancy.

CONCLUSIONS

TIS applies to serous fluids collected from the pleura, peritoneal, and pericardial cavities. Using TIS, indeterminate categories are presented as either preliminary or as options of last resource. TIS has emphasized the role of ancillary tests in arriving at the correct interpretation within each category. It also has emphasized the importance of a malignant diagnosis as a definitive diagnosis, comparable to histologic examinations. Because of the well-documented outcomes in the adoption of uniform cytology terminology for other organ systems, we recommend the use of the upcoming TIS and believe its use will be paramount to improving the diagnostic yield in this area of cytology.

Collection and Handling of Thoracic Small Biopsy and Cytology Specimens for Ancillary Studies: Guideline From the College of American Pathologists in Collaboration With the American College of Chest Physicians, Association for Molecular Pathology, American Society of Cytopathology, American Thoracic Society, Pulmonary Pathology Society, Papanicolaou Society of Cytopathology, Society of Interventional Radiology, and Society of Thoracic Radiology

CONTEXT.—

The need for appropriate specimen use for ancillary testing has become more commonplace in the practice of pathology. This, coupled with improvements in technology, often provides less invasive methods of testing, but presents new challenges to appropriate specimen collection and handling of these small specimens, including thoracic small biopsy and cytology samples.

OBJECTIVE.—

To develop a clinical practice guideline including recommendations on how to obtain, handle, and process thoracic small biopsy and cytology tissue specimens for diagnostic testing and ancillary studies.

METHODS.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. Core needle biopsy, touch preparation, fine-needle aspiration, and effusion specimens with thoracic diseases including malignancy, granulomatous process/sarcoidosis, and infection (eg, tuberculosis) were deemed within scope. Ancillary studies included immunohistochemistry and immunocytochemistry, fluorescence in situ hybridization, mutational analysis, flow cytometry, cytogenetics, and microbiologic studies routinely performed in the clinical pathology laboratory. The use of rapid on-site evaluation was also covered.

RESULTS.—

Sixteen guideline statements were developed to assist clinicians and pathologists in collecting and processing thoracic small biopsy and cytology tissue samples.

CONCLUSIONS.—

Based on the systematic review and expert panel consensus, thoracic small specimens can be handled and processed to perform downstream testing (eg, molecular markers, immunohistochemical biomarkers), core needle and fine-needle techniques can provide appropriate cytologic and histologic specimens for ancillary studies, and rapid on-site cytologic evaluation remains helpful in appropriate triage, handling, and processing of specimens.

Diagnosis and categorization of malignant effusions: A 6-year review from a single academic institution

BACKGROUND

Cytologic detection of malignant cells in pleural, peritoneal, or pericardial effusion most likely indicates advanced stage of malignant disease. There are a few studies updating the categorization of malignant effusions.

METHODS

The electronic pathology database was searched to identify consecutive cases of malignant effusion during a 6-year period. Patient age and gender, origins of known malignancy, and cytologic diagnoses were recorded and summarized.

RESULTS

A total of 1059 specimens included 561 (53%) pleural, 441 (41.6%) peritoneal, and 57 (5.4%) pericardial fluids. Most of the pleural (516, 92.0%), peritoneal (418, 94.8%), and pericardial (53, 93.0%) specimens were derived from patients with a single known malignancy. More common origins involving pleural fluid were lung (152, 27.1%) followed by breast (103, 18.4%) and gastrointestinal tract (76, 13.5%). The most common etiology for women and men was breast (102, 30.8%) and lung (67, 36.2%), respectively. More common origins involving peritoneal fluid were gastrointestinal (158, 35.8%) and gynecologic (156, 35.4%) tracts, and breast (46, 10.4%). The most common etiology for women and men was Mullerian (156, 55.5%) and gastrointestinal tract (94, 68.6%), respectively. Most common origins involving the pericardial fluid were breast (20, 37.7%) and lung (17, 29.8%). Breast and lung were the most common etiology for women (20, 57.1%) and men (8, 44.4%), respectively.

CONCLUSIONS

Breast and lung remain to be the most common origin of both malignant pleural and pericardial effusion for women and men, respectively. The most common origin involving peritoneal effusion is Mullerian for women and gastrointestinal tract for men.

Proceedings of the American Society of Cytopathology Companion Session at the 2019 United States and Canadian Academy of Pathology Meeting Part 1: towards an International System for Reporting Serous Fluid Cytopathology

INTRODUCTION

The International System for the Reporting of Serous Fluid Cytopathology was initiated to provide a common language for cytopathology reports on body fluids.

MATERIALS AND METHODS

The International Academy of Cytology and the American Society of Cytopathology collaborated to provide evidence-based and expert-driven terminology for reporting serous fluids. Lead editors were selected and expert authors invited to form working groups for the diagnostic categories and special sections.

RESULTS

Preliminary results of the collaboration include the 6 diagnostic terminology categories: non-diagnostic, negative for malignancy, atypia of undetermined significance, suspicious for malignancy, malignant-primary, and malignant-metastatic. Four special sections on ancillary testing, peritoneal washings, cytotechnical aspects, and quality assurance will appear in the final text. Initial results of an international survey indicate strong support for a uniform terminology for reporting serous fluids.

CONCLUSIONS

This article outlines the initial findings of the collaboration as presented to the United States and Canadian Academy of Pathology at the 2019 annual meeting at the National Harbor, MD.

Determination of the optimal volume of ascitic fluid for the precise diagnosis of malignant ascites

BACKGROUND/AIMS

The aim of this study was to determine the optimal volume of peritoneal effusion required to diagnose malignant ascites.

PATIENTS AND METHODS

The authors recruited 123 patients with shifting dullness and obtained 123 peritoneocentesis fluid samples. The samples were divided into seven aliquots of 10, 50, 100, 150, 200, 250, and 300 mL for cytopathological examination. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated for each aliquot.

RESULTS

The sensitivity for the diagnosis of malignant ascites gradually increased as the sample volume increased and reached a constant value at a volume of 200 mL. The sensitivity and NPV for the 10-, 100-, and 150-mL volumes were significantly different from those for the 200-mL sample. However, the sensitivity and NPV for the 250- and 300-mL volumes were not significantly different. The sensitivity for the diagnosis of malignant ascites is closely related to the volume of peritoneal fluid that is extracted by peritoneocentesis.

CONCLUSION

We suggest a volume of 200 mL as the optimal minimum volume to confirm malignant ascites in patients with shifting dullness.

A 2-year retrospective study on pleural effusions: A cancer centre experience

BACKGROUND

Cytopathological examination of pleural effusions is a fast and minimally invasive method for verification of the presence of neoplastic cells. We report our 2-year experience using a categorised diagnostic system and reporting risks of malignancy (ROMs) for each defined category.

METHODS

Cytological reports of patients between November 2016 and October 2018 were collected, with results primarily classified into a five-tiered classification scheme. Immunohistochemistry markers used in cytology and their results were also recorded. Final agreement to histology and overall test performance was calculated for cases with available concomitant (up to 3 months) pleural biopsies.

RESULTS

A total of 519 samples from 385 patients were collected, being 29 (5.6%) classified as non-diagnostic, 291 (56%) as negative, 28 (5.4%) as atypical, 30 (5.8%) as suspicious and 141 (27.2%) as positive. Most requested markers were calretinin, TTF1, Ber-EP4 and Gata-3, being conclusive in 45 (76.3%) cases. Total cyto-histological agreement was achieved in 49 (80.3%) specimens, with an overall sensitivity and specificity of 69.4% and 93.3%, respectively. Positive predictive value was 96.2% and negative predictive value was of 56%. ROM for each diagnostic category was 50% for non-diagnostic, 44% for negative, 50% for atypical, 83.3% for suspicious and 96.2% for positive.

CONCLUSIONS

Our 2-year retrospective study has shown a high specificity and positive predictive value for pleural cytology. The use of a five-tiered system has also shown to be highly effective, with a concordantly progressive higher ROM for the assigned diagnostic categories.

ERS/EACTS statement on the management of malignant pleural effusions

Malignant pleural effusions (MPE) are a common pathology, treated by respiratory physicians and thoracic surgeons alike. In recent years, several well-designed randomized clinical trials have been published that have changed the landscape of MPE management. The European Respiratory Society (ERS) and the European Association for Cardio-Thoracic Surgery (EACTS) established a multidisciplinary collaboration of clinicians with expertise in the management of MPE with the aim of producing a comprehensive review of the scientific literature. Six areas of interest were identified, including the optimum management of symptomatic MPE, management of trapped lung in MPE, management of loculated MPE, prognostic factors in MPE, whether there is a role for oncological therapies prior to intervention for MPE and whether a histological diagnosis is always required in MPE. The literature revealed that talc pleurodesis and indwelling pleural catheters effectively manage the symptoms of MPE. There was limited evidence regarding the management of trapped lung or loculated MPE. The LENT score was identified as a validated tool for predicting survival in MPE, with Brims' prognostic score demonstrating utility in mesothelioma prognostication. There was no evidence to support the use of oncological therapies as an alternative to MPE drainage, and the literature supported the use of tissue biopsy as the gold standard for diagnosis and treatment planning.Management options for malignant pleural effusions have advanced over the past decade, with high-quality randomized trial evidence informing practice in many areas. However, uncertainties remain and further research is required http://ow.ly/rNt730jOxOS.

Baseline predictors of negative and incomplete pleural cytology in patients with suspected pleural malignancy - Data supporting 'Direct to LAT' in selected groups

OBJECTIVES

Negative effusion cytology is more common in certain forms of Malignant Pleural Effusion (MPE) and results in pathway delay. Local Anaesthetic Thoracoscopy (LAT) is extremely sensitive and safe but cannot be offered to all. A stratified pathway, including 'Direct to LAT' in selected cases could enhance patient experience but requires reliable baseline predictors of unhelpful cytology, including both negative (no malignant cells) and incomplete results (malignant cells identified but predictive markers failed), since pleural biopsies will be required in the latter for optimal management. This retrospective analysis of a prospective multi-centre study, sought to identify baseline features for pathway rationalization.

MATERIALS AND METHODS

363/638 (57%) of patients recruited to the DIAPHRAGM study (ISRCTN10079972) were included. Prospective data, including final diagnoses, asbestos exposure and fluid cytology results were supplemented by retrospective Computed Tomography (CT) and predictive marker reports. Independent predictors of negative and incomplete cytology were determined by multivariable logistic regression. Contingency tables were used to assess diagnostic value of cytology in associated phenotypes.

RESULTS

238/363 (66%) patients were diagnosed with MPE (18 tumour types). Fluid cytology was negative in 151/238 (63%) and independently associated with asbestos-exposure (Odds Ratio (OR) 5.34) and a malignant CT (OR 2.25). When both features were recorded the sensitivity and negative predictive value of fluid cytology were 19% (95% CI 11-30%) and 9% (95% CI 4-20%)), respectively. Cytology was incomplete in 34/238 (14%), i.e. 47% of positive cytology cases) but was not associated with any baseline feature. ORs for incomplete cytology in Ovarian, Breast, Renal and Lung Cancer were 83, 22, 21 and 9, respectively.

CONCLUSION

Negative cytology is extremely likely in patients with asbestos exposure and a malignant CT report. A 'Direct-to-LAT' approach may be appropriate in this setting. No baseline predictors of incomplete cytology were identified.

Label-free microfluidic chip for the identification of mesothelial cell clusters in pleural effusion

The detection of tumor cells and clusters in pleural effusion assists in the diagnosis of lung cancer. The proportion of tumor cells and clusters to the total number of cells in each patient varies substantially due to individual differences and the severity of the disease. The identification of one tumor cell or cluster from a large number of pleural effusions is the main challenge for hydrothorax tumor cell detection techniques. In the present study, by using A549 lung cancer and Met-5A mesothelial cell lines, a label-free microfluidic chip based on cell cluster size was designed. By setting the parameters of the chip, individual cells and clusters were able to enter different microfluidic channels. Subsequent to non-specific staining, the recovered components were stained using acridine orange (AO). A charge-coupled device camera was used to captured images of the cell, and the features of these cells were analyzed in their R and G channels using Matlab software to establish the characteristics and finally differentiate between the tumor and non-tumor cell or clusters. According to the results, when inlet A and B were under a velocity of 10 and 8.5 ml/h, respectively, the tumor cell clusters were successfully collected through microfluidic channels III–V, with a recovery rate of ~80%. Subsequent to staining with AO, the feature values in the R and G channels were identified, and initial differentiation was achieved. The present study combined the microfluidic chip, which is based on cluster size, with a computer identification method for pleural effusion. The successful differentiation of tumor cell clusters from non-tumor clusters provides the basis for the identification of tumor clusters in hydrothorax.

Comparative Analysis of Flow Cytometry and Cytomorphology for Neuroblastoma Cell Detection in Effusion and Bone Marrow Specimens

Background：Neuroblastoma (NB) frequently metastasizes to the bone marrow (BM), pleural and peritoneal cavities. The detection of NB cells in the BM and effusion specimens is important in clinical staging. Objective: The aim of this study was to compare the ability of flow cytometry (FCM) and cytomorphology (CM) in detecting NB cells. Materials and methods：From 21 patients with suspected NB metastasis, BM and effusion specimens were analyzed by FCM and CM. Results：A total of 16 effusion (76.2%) and 9 BM (42.9%) specimens were classified by FCM as positive for malignancy. CM revealed 12 (57.1%) and 9 (42.9%) positive effusion and BM specimens, respectively. There were three effusions detected by CM but not by FCM. There was no significant differences between FCM and CM in the detection of NB cells in effusions (p = 0.344). Conclusions：FCM can be used as an adjunct to CM for the detection of NB cells in effusion specimens.

Management of cytological material, pre-analytical procedures and bio-banking in effusion cytopathology

Serous effusion fluid is one of the most commonly encountered specimens in routine cytopathology practice. It provides invaluable information about the patient and the clinical status; but to get the most of it, specimen handling and processing must be carried out properly. Cytomorphology is the basis of a successful analysis which should complemented by ancillary tests when needed. A wide spectrum of ancillary techniques - ranging from immunocytochemistry and flow cytometry to different assays of molecular pathology - can be applied to serous effusions. This article describes the acquisition and management of serous effusion fluids, methods for preservation and transportation, different techniques of cytopreparation, application of immunocytochemistry, flow cytometry, and fluorescence in-situ hybridization (FISH), as well as DNA extraction for polymerase chain reaction (PCR) and next generation sequencing (NGS). Principles of bio-banking of effusion samples are also discussed which is getting more important in correlation with the developments in personalized medicine.