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

Diagnostic impact of safety protocols for processing peritoneal washing specimens during the global pandemic of coronavirus disease 2019: A comparative study from 195 cytological samples

Background

The global pandemic of the coronavirus disease 2019 represents a major concern for health services worldwide, and has also induced major changes in cytopathology practice.

Aim

We aimed to verify the diagnostic performance of cytological evaluation under a new safety protocol during the pandemic compared to the standard pre‐pandemic procedure. We also aimed to assess how cytological diagnoses and sampling were impacted during the pandemic period compared to the pandemic‐free period in 2019.

Materials and methods

Cytological samples of peritoneal washings taken during the first 10 months of the pandemic emergency in Italy (March 11, 2020 to January 11, 2021) were compared to samples from the preceding 10‐month time frame (May 11, 2019 to March 10, 2020).

Results

One hundred ninety‐five specimens were analysed in the present study. We observed no noticeable differences in cytological diagnoses during the pandemic period compared to the pre‐pandemic period. The case numbers by diagnostic category for the pre‐pandemic vs pandemic periods, respectively, were as follows: non‐diagnostic, 0 vs 0 cases; negative for malignancy, 86 vs 52 cases; atypia of uncertain significance, 7 vs 1 cases; suspicious for malignancy, 0 vs 2 cases; malignant, 42 vs 4 cases.

Conclusion

While a consistent reduction in the number of cytological examinations has been observed during the COVID‐19 period, our institutional safety protocol for processing cytological samples did not affect the diagnostic reliability of peritoneal washing cytology.

Malignant pericardial effusion complicated by cardiac tamponade under atezolizumab

Immune-related adverse events including cardiac toxicity are increasingly described in patients receiving immune checkpoint inhibitors. We described a malignant pericardial effusion complicated by a cardiac tamponade in an advanced non-small cell lung cancer patient who had received five infusions of atezolizumab, a PDL-1 monoclonal antibody, in combination with cabozantinib. The definitive diagnosis was quickly made by cytology examination showing typical cell abnormalities and high fluorescence cell information provided by the hematology analyzer. The administration of atezolizumab and cabozantinib was temporarily discontinued due to cardiogenic hepatic failure following cardiac tamponade. After the re-initiation of the treatment, pericardial effusion relapsed. In this patient, the analysis of the pericardial fluid led to the final diagnosis of pericardial tumor progression. This was afterwards confirmed by the finding of proliferating intrapericardial tissue by computed tomography scan and ultrasound. This report emphasizes the value of cytology analysis performed in a hematology laboratory as an accurate and immediate tool for malignancy detection in pericardial effusions.

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.

Identification and characterization of effusion tumor cells (ETCs) from remnant pleural effusion specimens

BACKGROUND

Cancer is a leading cause of death worldwide, and patients may have advanced disease when diagnosed. Targeted therapies guided by molecular subtyping of cancer can benefit patients significantly. Pleural effusions are frequently observed in patients with metastatic cancer and are routinely removed for therapeutic purposes; however, effusion specimens have not been recognized as typical substrates for clinical molecular testing because of frequent low tumor cellularity.

METHODS

Excess remnant pleural effusion samples (N = 25) from 21 patients with and without suspected malignancy were collected at Stanford Health Care between December 2019 and November 2020. Samples were processed into ThinPrep slides and underwent novel effusion tumor cell (ETC) analysis. The ETC results were compared with the original clinical diagnoses for accuracy. A subset of confirmed ETCs was further isolated and processed for molecular profiling to identify cancer driver mutations. All samples were obtained with Institutional Review Board approval.

RESULTS

The authors established novel quantitative standards to identify ETCs and detected epithelial malignancy with 89.5% sensitivity and 100% specificity in the pleural effusion samples. Molecular profiling of confirmed ETCs (pools of 5 cells evaluated) revealed key pathogenic mutations consistent with clinical molecular findings.

CONCLUSIONS

In this study, the authors developed a novel ETC-testing assay that detected epithelial malignancies in pleural effusions with high sensitivity and specificity. Molecular profiling of 5 ETCs showed promising concordance with the clinical molecular findings. To promote cancer subtyping and guide treatment, this ETC-testing assay will need to be validated in larger patient cohorts to facilitate integration into cytologic workflow.

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.

Clinico-pathological significance of suspicious peritoneal cytology in endometrial cancer

BACKGROUND AND OBJECTIVES

Suspicious peritoneal cytology refers to the result of peritoneal cytology testing that is insufficient in either quality or quantity for a definitive diagnosis of malignancy. This study examined characteristics and survival outcomes related to suspicious peritoneal cytology in endometrial cancer.

METHODS

A population-based retrospective study by querying the National Cancer Institute's Surveillance, Epidemiology, and End Results Program was conducted. A total of 41,229 women with Stage I-III endometrial cancer who had peritoneal cytologic sampling at hysterectomy from 2010 to 2016 were examined. A Cox proportional hazard regression model and a competing risk analysis with Fine-Gray model were fitted to assess survival outcome related to suspicious peritoneal cytology.

RESULTS

Suspicious peritoneal cytology was seen in 702 (1.7%) cases. In multivariable models, suspicious peritoneal cytology was associated with increased risk of endometrial cancer mortality (subdistribution-hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.29-2.20, p < 0.001) and all-cause mortality (adjusted-HR: 1.55, 95% CI: 1.27-1.90, p < 0.001) compared with negative peritoneal cytology. Sensitivity analysis demonstrated that suspicious peritoneal cytology had discrete overall survival improvement compared with malignant peritoneal cytology in a propensity score weighting model (HR: 0.85, 95% CI: 0.72-0.99, p = 0.049).

CONCLUSION

Our study suggests that suspicious peritoneal cytology may be a prognostic factor for decreased survival in endometrial cancer.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Cytomorphology, Immunophenotype, and cytogenetic profile of leukemic serous effusions

BACKGROUND

Serous effusions (SE) in leukemic patients can be due to infections, therapy, volume overload, lymphatic obstruction or malignancy having implications on treatment and mortality. The objective of the present study is to highlight the spectrum of cytomorphology, immunophenotype, and cytogenetics in leukemic serous effusions (LSE).

MATERIALS

Present study is retrospective and descriptive. We reviewed all the SE, which were reported as suspicious or positive of leukemic infiltration from 2016 to 2019 for cytomorphological features. CSF and effusions involved by lymphomas were excluded. Cyto-diagnosis was compared with primary proven diagnosis (by ancillary techniques) and disconcordant cases were analyzed.

RESULTS

Out of total 9723 effusions, only 0.4% (n = 40) showed leukemic involvement and included nine cases of AML, three of B-ALL, 13 T-ALL, 2 MPAL, 6 CML, 5CLL, one each of chronic myelomonocytic leukemia and AML with myelodysplasia. The most common site of involvement was the pleural cavity (n = 30), followed by the peritoneal cavity (n = 7) and the pericardial cavity (n = 3). T -ALL (41.9%) was the most common leukemia involving pleural fluid followed by AML (23.3%). CML (42.8%) was the most common leukemia involving the ascitic fluid followed by B-ALL (28.6%). Accurate diagnosis was given on cytomorphology in 72.5% (29/40) cases and 15.0% (6/40) were reported as non-Hodgkin lymphoma.

CONCLUSION

Cytology is an effective tool available to make a diagnosis of LSE. Nuclear indentations in large atypical cells and cells with eosinophilic granular cytoplasm with sparse or abundant eosinophils in the background are an important clue in favor of leukemia over lymphoma.

A decade of change: Trends in the practice of cytopathology at a tertiary care cancer centre

OBJECTIVES

The practice of cytopathology has evolved over the past decade with a growing need for doing more with less tissue. Changes in clinical practice guidelines and evolving needs in tissue acquisition for diagnosis and treatment have affected various areas of cytopathology in different ways. In this study, we evaluated the changing trends in cytopathological practice at our institution over the past decade.

METHODS

We performed a retrospective review of our institutional database for cytopathology cases from calendar years 2009 (n = 28038) and 2019 (n = 31386) to evaluate the changing trends in practice.

RESULTS

The overall number of exfoliative cases decreased 10% over the past decade, primarily due to a 64% decrease in gynaecological Pap testing. However, the volume of serous body cavity and cerebrospinal fluids increased 125% and 44%, respectively. The overall volume of fine needle aspiration (FNA) cases increased 38% from 2009 to 2019. The number of FNA cases increased across most body sites, driven primarily by a 180% increase in endobronchial ultrasound-guided transbronchial needle aspiration cases. In contrast, breast FNA volume decreased 43%. Ancillary studies increased substantially over the past decade, including immunostains (476%) and molecular testing (250%).

CONCLUSIONS

The trends in our cytopathological practice showed an increased volume of cases, especially in non-gynaecological specimens. As expected, the number of FNA cases used for immunostains and molecular testing increased substantially, indicating an upward trend in ancillary studies in cytopathological practice.

Association Between Adjuvant Therapy and Survival in Stage II-III Endometrial Cancer: Influence of Malignant Peritoneal Cytology

OBJECTIVE

The aim of this study was to examine the survival effect of adjuvant therapy in stage II-III endometrial cancer based on peritoneal cytology results.

METHODS

The National Cancer Institute's Surveillance, Epidemiology, and End Results Program was retrospectively queried to examine 7467 women with stage II-III endometrial cancer who underwent hysterectomy, and with available peritoneal cytology results, from 2010 to 2016. A Cox proportional hazard regression model was fitted to assess the association between adjuvant therapy and all-cause mortality stratified by peritoneal cytology results.

RESULTS

Malignant peritoneal cytology was reported in 1662 (22.3%) women and was associated with non-endometrioid histology, higher tumor stage, and nodal metastasis (p < 0.05). In a propensity score-weighted model, malignant peritoneal cytology was associated with increased all-cause mortality compared with negative peritoneal cytology (hazard ratio 1.35, 95% confidence interval 1.23-1.48). Adjuvant therapy types varied based on histology and peritoneal cytology results. In non-endometrioid histology, the combination of chemotherapy and whole pelvic radiotherapy (WPRT) was associated with improved overall survival compared with chemotherapy or WPRT alone irrespective of the peritoneal cytology results (p < 0.05). The combination of chemotherapy and WPRT was also associated with improved overall survival in women with endometrioid histology and malignant peritoneal cytology (p = 0.026). Women with endometrioid histology and negative peritoneal cytology represented the most common subpopulation (46.5%), and overall survival was similar regardless of which of the three adjuvant therapy modalities was used (p = 0.319).

CONCLUSIONS

Malignant peritoneal cytology is prevalent and prognostic in stage II-III endometrial cancer. This study found that the surgeon's choice and benefit of adjuvant therapy for women with stage II-III endometrial cancer differed depending on the status of peritoneal cytology.

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.

Immunochemistry in the work-up of mesothelioma and its differential diagnosis and mimickers

The differential diagnosis in cellular effusions with cytological atypia often includes malignant mesothelioma (MM), reactive mesothelial proliferation, and malignancies of metastatic origin, particularly carcinomas. The International Reporting System for Serous Fluid recently established guidelines for reporting MM. In conjunction with the cytomorphologic evaluation, the role of immunochemistry (IC) was emphasized as a very useful tool in the workup of serous fluids, especially with the availability of novel markers. Utilizing a panel of markers, IC allows the characterization of the cells, whether mesothelial or not, and when mesothelial origin is established, IC can frequently assist in delineating its benign or malignant nature. IC can also confirm metastatic disease, allowing the identification of the primary origin in most cases. This review summarizes the current status of IC and its role in the diagnosis of MM and its differential diagnosis in serous fluids.

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.

Application of Indian Academy of Cytologists Guidelines for Reporting Serous Effusions: An Institutional Experience

Background:

Recently, the Indian Academy of Cytologists (IAC) has published the guidelines for interpretation and reporting of serous effusions. Till date, there are no studies on its applicability.

Aims:

The present study was carried out to assess the feasibility of applying the IAC reporting categories to effusions, determine the frequency, and provide an estimate of the risk of malignancy (ROM) for individual diagnostic categories.

Materials and Methods:

All cases of serous effusion fluids reported in the year 2019 were retrieved from the archives and reassigned as per the IAC diagnostic categories. The clinical and histopathological follow-up information was obtained wherever possible.

Results:

A total of 1340 effusion samples were received from 1085 patients. There were 561 (51.7%) males and 524 (48.3%) females. Majority were pleural (1066, 79.5%), followed by peritoneal (187, 14%) and pericardial (87, 6.5%) effusions. The age ranged from 7 months to 92 years. There were 35 (2.6%) samples in category 1 (non-diagnostic), 954 (71.2%) in category 2 (benign), 17 (1.3%) in category 3 (atypical), 59 (4.4%) in category 4 (suspicious for malignancy) and 275 (20.5%) in category 5 (malignant). The estimated ROM in serous effusion samples was 20% for category 1, 16.7% for category 2, 50% for category 3, 94.4% for category 4 and 100% for category 5.

Conclusions:

The categorization of serous effusion cytology samples as per the IAC diagnostic categories and as per the reporting format developed by the IAC is feasible and the management recommendations are mostly appropriate.

Peritoneal lavage cytology in the diagnosis of pelvic endometriosis

BACKGROUND

We aimed to assess the sensibility, specificity, and predictive values of cytology of the fluid sediment in patients with pelvic endometriosis diagnosed based on laparoscopic-guided biopsy.

METHODS

Between January 2017 and September 2018, 71 specimens of peritoneal fluid collected by laparoscopy were evaluated. Fifty-three patients were diagnosed laparoscopically and histologically with endometriosis, and 18 were considered controls (without suspicious endometriosis lesions). We calculated the sensitivity, specificity, the positive and negative predictive value, and the accuracy of endometrial-like cells (ELC) and hemosiderin-laden macrophages (HLM) in the fluid sediment.

RESULTS

Of the 50 patients with endometriosis, 32 (64%) had HLM, 9 (18%) had ELC, and 7 (14%) had both elements. Of the 18 patients without endometriosis, 3 (16%) had HLM, 2 (11%) had ELC, and 1 (5%) had both ELC and HLM. The sensitivity of the cytology of peritoneal fluid sediment for the diagnosis of endometriosis, based on the presence of ELC, was 18%, the specificity was 83%, the positive predictive value was 82%, the negative predictive value was 28.7%, and the accuracy was 36.8%. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy based on the presence of HLM were 64%, 83%, 91%, 45.5%, and 69.1%, respectively.

CONCLUSION

The study of peritoneal fluids obtained laparoscopically from women undergoing evaluation for endometriosis may identify patients with the disease.

Evaluation of pelvic washing specimens in patients with endometrial cancer: Cytomorphological features, diagnostic agreement, and pathologist experience

BACKGROUND

Pelvic washings for patients with endometrial cancer is recommended but not used for staging. The International System for Reporting Serous Fluid Cytology (TIS) has standardized diagnostic categories, but the criteria remain incomplete. The 3 primary goals of this study were to 1) investigate features that distinguish atypical/indeterminate from malignant specimens, 2) measure the level of agreement between chart and reviewer diagnoses, and 3) determine whether the number of years in practice had an effect on the diagnoses rendered.

METHODS

Pelvic washings and surgical pathology specimens for 52 patients with a chart diagnosis of atypical/indeterminate, suspicious, or malignant cytology and 52 age-matched controls with a negative chart diagnosis were included, reviewed blindly by 2 cytopathologists, and assigned a study diagnosis. Morphologic features were assessed. Agreement between original chart diagnoses and reviewer diagnoses were assessed as well as effect of years in practice.

RESULTS

The overall cellularity in cell block (CB) slides for the malignant category was significantly increased compared with the atypical/indeterminate category (P < .0001). In addition, the number of atypical groups in ThinPrep for malignant washings was significantly increased compared with the atypical category (P < .001) and the negative and suspicious categories (P < .0001) in the CB. Overall agreement between the original and adjudicated diagnoses was high (γ = 0.983). There was no significant difference between diagnoses rendered and years in practice.

CONCLUSION

The overall cellularity and number of atypical cells can be used to distinguish between malignant and atypical pelvic washing specimens. There is high reproducibility in the diagnostic categories and high agreement among pathologists, regardless of practice experience. These findings can help refine the criteria for TIS.

Current classification systems and standardized terminology in cytopathology

The history of classification systems and the search for a unified nomenclature in cytopathology spans several decades and expresses the preoccupation of all those involved to make cytopathology a reliable diagnostic tool and a trusted screening method. Early classification schemes, applicable to exfoliative and aspiration cytology, attempted to set some basic standards for how non-gynecological cytopathology findings should be reported. While useful in establishing some basic guidelines, these were not specific to the various fields of non-gynecologic cytopathology, often burdened with specific problems. Cytopathology has evolved tremendously in the last couple of decades, undoubtedly boosted by the emergence of various classification schemes that, more than ever, are based on evidence gathered by professionals across the globe. The benefit of classification systems and standardized nomenclature in cytopathology is to provide useful, clear, and clinically relevant information for clinicians and ultimately to provide the best patient care. Standardized reporting systems make cytopathology reports more meaningful and robust. It now became standard that these include by default elements, such as adequacy criteria, diagnostic groups, risk of malignancy (ROM), and recommendations for patient management. In this brief review, we attempted to summarize how these classification schemes emerged and how they are reshaping the landscape of diagnostic cytopathology.