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

The International System for Serous Fluid Cytopathology (TIS) survey in preparation for TIS 2.0

INTRODUCTION

The International System for Serous Fluid Cytopathology (TIS) has gained acceptance and has led to literature validating original concepts and suggesting refinements. In preparation for the second edition of TIS, editors generated a survey to solicit experience with and opinions about TIS.

MATERIALS AND METHODS

An online survey available from March 8 to June 15, 2024, included 56 questions, offered in 7 languages, related to the practice of serous fluid cytopathology.

RESULTS

A total of 598 respondents accessed the survey. Information was collected regarding certification, work setting, work volume and years in practice. In the respondent group, 78% (401 of 513) were pathologists, 18% (92 of 513) cytologists of cytotechnologists, 2% (10 of 513) trainees, and 2% (10 of 513) medical scientists. A total of 23% of participants came from academia. Also, 59% of respondents were (280 of 474) from Asia, 17% Europe, 12% North America, and 10% South America. In all, 61% (287 of 474) have adopted TIS. Over 50% issue a preliminary report awaiting ancillary test results. Another 20% issue such a report depending on circumstance. The most frequent request for refinement of criteria centered around Atypia of Uncertain Significance (AUS). Only small numbers of participants provided data on diagnostic category percentage and risk of malignancy (ROM); however, those that did reported a decrease in nondiagnostic and atypical results with corresponding decreases in ROM for those categories. Variable use of cytochemical and immunocytochemical stains for resolving mesothelial proliferations was reported. Respondents indicated a desire for incorporation of recommendations on clinical management and extension of TIS into body fluid types beyond pleural, pericardial, and peritoneal.

CONCLUSIONS

This survey examines acceptance of TIS and advice for future directions.

Pericardial effusion cytology: malignancy rates, patterns of metastasis, comparison with pericardial window, and genomic correlates

INTRODUCTION

Cytologic evaluation of pericardial fluid is essential for diagnosing malignant pericardial effusions secondary to metastatic disease and for guiding appropriate clinical management; however, large cohort and up-to-date studies on malignancy rates and distribution of primary tumor sites is lacking.

MATERIALS AND METHODS

A retrospective analysis of pericardial fluid specimens from 2 large academic medical centers over a 10-year period was conducted. Clinical and specimen characteristics were correlated with cytologic diagnoses, and compared with surgical pathology pericardial specimens when available. In addition, genomic testing results were examined in a subset of malignant cases.

RESULTS

A total of 1667 pericardial fluid specimens were evaluated, with 15.3% diagnosed as malignant. Lung cancer (50.6%) was by far the most common primary tumor causing malignant pericardial effusions, followed by breast (13.0%), hematolymphoid (12.6%), and gastrointestinal (6.1%) cancers. A subset of patients with paired cytology and surgical pathology pericardial specimens showed concordance in 84.2% of cases, with discordant cases more frequently presenting with a positive cytology but negative surgical pathology result. Genomic analysis of a subset of malignant pericardial effusions revealed the most frequently mutated genes to be TP53, KRAS, CDKN2A/B, and PIK3CA, with a larger proportion of high tumor mutational burden (≥10 muts/Mb) in pericardial fluid samples compared to primary or metastatic sites.

CONCLUSIONS

While lung cancer is the most frequent cause of a cytology-confirmed malignant pericardial effusion, familiarity with relative frequencies of metastases from other sites can be particularly helpful, especially in the diagnostic work-up of an occult malignant pericardial effusion.

Impact of serous fluid volume on next-generation sequencing: a significant step forward for optimization of serous fluid sample collection

INTRODUCTION

Current literature lacks data regarding the influence of serous fluid volume (SFV) on next-generation sequencing (NGS) performed on malignant cases. In this study, we highlight the impact of SFV and other parameters influencing the outcome of NGS analysis.

MATERIALS AND METHODS

We evaluated 827 samples of serous fluids from 607 patients. Of these, 72 samples underwent NGS analysis. Effusion volume, tumor cellularity, DNA, and RNA quality metrics, as well as clinicopathologic and molecular data were evaluated. Pleural fluid accounted for 56.3% of the fluid samples collected. The most common primary tumor site was gastrointestinal/pancreatobiliary, adenocarcinoma was the most common histologic type. Overall mean volume was 293 mL. The mean Qubit DNA of the 72 effusion samples that underwent NGS analysis was 14.3 ng/μL and mean Qubit RNA was 28.2 ng/μL. The mean Qubit DNA concentration increases in SFV up to 100 mL only.

RESULTS

No correlation exists between SFV and mean tumor cellularity. In addition, 74.6% (50 of 67) of sequenced samples showed oncogenic drivers; KRAS was the most common driver followed by EGFR. Three cases displayed ALK fusions, and 1 case displayed NTRK1 fusion. The DNA yield is higher in SFV of 100 mL as a cutoff. Beyond 100 mL, there is no impact of SFV on DNA yield. SFV does not impact RNA yield and mean tumor cellularity. Effusion samples should be submitted for molecular testing despite low tumor cellularity.

CONCLUSIONS

Our results as a pilot study are important in optimization of SFV for both diagnosis as well as NGS analysis for improving management.

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.

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.