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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cytologic Histotyping of Gynecologic Malignancies in Peritoneal Fluids Is Reliable When Compared to Its Corresponding Surgical Specimen

BACKGROUND

Cytologic examination of peritoneal fluid (PTFL) often represents the first and only pathologic specimen available to guide management of gynecologic malignancies (GMs). This study examines the cytohistologic correlation between histotyping of GM in PTFL and its corresponding surgical specimen (SS).

METHODS

The study retrospectively identified positive PTFL with a GM between 2017 and 2022. Cytologic specimens (CSs) that were obtained after or concurrently with its diagnostic SS (biopsy/resection) were excluded. Root cause analysis of discordant cases was performed by reviewing morphology, specimen characteristics, and immunophenotype of CS.

RESULTS

GM affected 55.8% (502/899) of malignant PTFL, of which 15.7% (79)/22.3% (112) was the only/initial diagnostic sample, respectively. Compared to SS, when a subtype was rendered on CS (91.9%), the concordance rate is 91.2% (almost perfect agreement, K = 0.842). Factors contributing to incorrect/inadequate subtyping include specimen limitations (low volume and/or cellularity), cytopathologist preference, and insufficient immunophenotyping. In seven patients (1.4%), the CS was able to render a more definitive diagnosis than its preceding nondiagnostic SS due to the paucity of lesional cells.

CONCLUSION

When compared to SS, histotyping of GM in PTFL is reliable and, at times, can be more definitive than its surgical counterpart. In some cases, subtyping is limited by extrinsic factors (i.e., specimen limitations). In other cases, the responsible cytopathologist prefers not to subtype despite supportive morphologic and immunohistochemical features. This highlights an opportunity for improvement in the diagnosis/subtyping of GM in PTFL, which may be the initial or only diagnostic specimen prior to patient treatment.

Applicability of the International Cytopathology Reporting System of Serous Fluids in a Brazilian City

INTRODUCTION

The International Academy of Cytology and the American Society of Cytopathology developed the International System of Serous Fluid Cytopathology (TIS) to standardize cytological reports. Effusions in pleural, peritoneal, and pericardial cavities are valuable sources of information for medical diagnosis, especially in oncological scenarios. The TIS classification is divided into five categories: nondiagnostic (ND), negative for malignancy (NFM), atypia of uncertain significance (AUS), suspected malignancy (SFM), and malignant (MAL). It facilitates global communication between specialists, aiming for future clinical management guidelines based on malignancy risk assessment.

METHODS

This quantitative analytical and retrospective study evaluated serous fluids (pleural, pericardial, and peritoneal) sent to the Instituto de Patologia de Araçatuba (IPAT), São Paulo, Brazil, from public and private hospitals between January 2017 and December 2022. Epidemiological and clinical data were collected from institutional files, including biopsies and immunohistochemical results.

RESULTS

The study included 719 patients with 763 serous fluid samples (pericardial, pleural, and peritoneal) analyzed over 6 years. The majority of samples were from pleural effusions (n = 438; 57.4%), followed by peritoneal (n = 293; 38.4%) and pericardial effusions (n = 32; 4.2%). Samples were classified using the International Serous Fluid Cytopathology System (TIS), revealing the following distribution: ND (0.41%), NFM (70.30%), AUS (0.95%), SFM (11.90%), and MAL (16.44%). The risk of malignancy calculated for each category was ND 66.67%, NFM 23.39%, AUS 28.57%, SFM 48.28%, and MAL 84.17%.

CONCLUSION

The ROM was out of the interval proposed by the TIS in all categories. These findings suggest the applicability of TIS even outside of the cancer center environment, although the presented ROM frequencies were out of the recommended range.

Diagnostic accuracy of International System for Reporting Serous Fluid Cytopathology: A systematic review and meta-analysis in malignancy diagnosis

This study conducts the first meta-analysis to assess the aggregated risk of malignancy associated with each category of the International System for Reporting Serous Fluid Cytopathology (ISRSFC) for reporting serous effusion cytology, while also evaluating diagnostic accuracy. PubMed/MEDLINE and Embase were systematically searched using the keywords "(pleural, peritoneal, and pericardial effusions) AND (serous effusion cytology) OR (International System for Reporting Serous Fluid Cytopathology)". Articles underwent risk of bias assessment using the QUADAS-2 tool. After excluding inadequate samples, a meta-analysis determined sensitivity and specificity for different cutoff points, including "atypical considered positive," "suspicious of malignancy considered positive," and "malignant considered positive." Summary receiver operating characteristic curves assessed diagnostic accuracy, and the diagnostic odds ratio was pooled. Sixteen retrospective cross-sectional studies, totaling 19,128 cases, were included. Sensitivity and specificity for the "atypical and higher risk categories" considered positive were 77% (95% confidence interval [CI], 68%-84%) and 95% (95% CI, 93%-97%) respectively. For the "suspicious for malignancy and higher risk categories" considered positive, sensitivity and specificity were 57% (95% CI, 49%-65%) and 100% (95% CI, 99%-100%) respectively. Sensitivity and specificity for the "malignant" category considered positive for malignancy were 70% (95% CI, 60%-77%) and 99% (95% CI, 98%-99%), respectively. The pooled area under the curve ranged from 85% to 89.5% for each cutoff. This meta-analysis underscores the ISRSFC's accuracy in reporting serous fluid cytology. It emphasizes the diagnostic importance of the "suspicious" and "malignant" categories in identifying malignancy, and the role of the "benign" category in ruling out malignancy.

Risk of Malignancy in Effusions according to the International System for Serous Fluid Cytopathology: A Review

INTRODUCTION

The International Serous Fluid Cytopathology Reporting System (TIS) was developed to standardize communication among health professionals reporting analyses of serous fluid samples. The categories include non-diagnosis (ND), negative for malignancy (NFM), atypia of undetermined significance (AUS), suspected malignancy (SFM), and malignant (MAL). Each category was characterized by a risk of malignancy (ROM).

METHODS

We performed a literature review to analyze studies related to TIS using several sources, including PubMed, followed by a search of relevant cytopathology journal websites (American Cancer Society, Diagnostic Cytopathology, Journal of the American Society of Cytopathology, and Acta Cytologica and Cytopathology). The search included articles published between January 2020 and December 2023, using the terms "international AND serous fluid system."

RESULTS

We identified 257 articles, of which 20 addressed the inclusion and exclusion criteria. The overall ROMs for each category were 23.55% for ND, 16.46% for NFM, 50.78% for AUS, 91.34% for SFM, and 98.21% for MAL.

CONCLUSION

Considering the TIS-recommended ROM rates, the ND category was between the suggested intervals, while the SFM category rate was bigger than expected. The other categories (NFM, AUS, and MAL) were below expected values. SFM and MAL had a stronger association with MAL results. New studies are needed to determine each category's ROM rate from TIS accurately.

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

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

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

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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