Leonie Wheeldon

Background: This invited review for the special issue is a celebration of the continued growth of knowledge in the field of serous fluid cytopathology. Summary: The review begins by addressing the value of cytological examination of the fluid samples in conjunction with clinical, radiological and biochemical data interpreted by the treating physician. It then covers the advances in cytopreparatory techniques with special reference to existing and emerging ancillary techniques available to obtain maximal diagnostic, prognostic & therapeutic information for the practice of precision medicine. The concept of mesothelioma as a cytological diagnosis has been made possible in recent years through clinical research and advocacy by experts and this has added value to serous fluid samples especially when this is the only sampling method available for a patient. Advances in the recommended repertoire of immunostains and a standardised approach through the use of diagnostic categories has been made possible by the International system for reporting serous fluid cytopathology. The reporting system has found application to other types of fluid samples, most recently, cerebrospinal fluid cytology which will be included in the forthcoming edition of the terminology system and is introduced in this special issue. Key messages. The review charts a journey commemorating important landmarks in our current understanding of serous fluids in diagnostic cytopathology.

Objective: The aim of this study was to evaluate the concordance of in‐house epidermal growth factor receptor ( EGFR ) mutation testing using the Biocartis Idylla (Idylla) platform compared with next‐generation sequencing (NGS) for formalin‐fixed, paraffin‐embedded (FFPE) and liquid based cytology (LBC) samples. A secondary objective was to investigate the role of rapid on‐site evaluation (ROSE) in optimising sample adequacy, ensuring sufficient material is collected to facilitate comprehensive molecular testing in cases of lung adenocarcinoma. Methods: This retrospective study used data collected on patients between November 2022 and September 2024, a total of 180 samples, in which EGFR mutations were tested for using MiSEQ Next generation sequencing (NGS) platform or the Idylla Console. The source of the data was from the Royal Cornwall Histopathology Department. Results: Among 180 samples tested, 14 (7.78%) expressed various EGFR mutations by either NGS and/or the Idylla platform. Concordance was observed in 12 of the 14 cases (86%). However, NGS identified 2 mutations in which Idylla was unable to identify. Whilst Idylla was able to identify one EGFR Exon 21 L858R mutation in a sample in which NGS was unable to test due to insufficient material. LBC samples consistently demonstrated a higher sample quality for testing. With significantly lower CQ values on average 20.94 compared to 22.28 than that of FFPE samples ( p = 0.00151 3.s.f). Conclusions: The Idylla Console demonstrates high concordance with NGS and effectively complements molecular diagnostics in resource and time‐constrained settings. 5.5% of cases tested using the NGS resulted in insufficient or failed testing suggesting a need for multi‐platform testing. LBC samples, particularly with the utilisation of ROSE, enhance testing quality and efficiency, offering a robust alternative to FFPE samples.

ObjectiveRapid On-Site Evaluation (ROSE) of fine needle aspirations (FNA) is widely accepted as best practice, resulting in better outcomes and delivery of care for patients. However, it is not always practical for cytology laboratories to release staff. To increase the availability of ROSE, this study aimed to robustly test the effectiveness of Telecytology ROSE (TCROSE) utilising a clinical imaging assistant (CIA) to prepare the samples and operate the microscope.MethodsThe study was divided into 3 phases. Phase 1, equipment testing, validation and in-house training for the CIA and the Consultant Biomedical Scientist (CBMS) performing TCROSE. Phase 2, Verifying TCROSE on the same site as the cytology laboratory and phase 3, TCROSE utilising a clinic at a peripheral site away from the cytology laboratory.Results78/80 (97% sensitivity, 95% accuracy) of TCROSE cases matched the final report for assessment of adequacy and sufficient sampling, demonstrating 94% reliability with a 95% confidence value. An appropriately trained CIA effectively prepared the samples and operated the microscope for remote interpretation. The samples were triaged effectively, and biopsy requests were appropriate to reduce the need for repeat procedures and delays in treatment. This approach received positive feedback from patients.ConclusionTCROSE utilising a CIA provides a highly effective alternative to conventional ROSE, minimising the resources required from cytopathology services and improving patient care and access to best practice. This study supports the validity of trained CIAs for a more involved role in the ultrasound-guided FNA service. TCROSE utilising a CIA provides a highly effective alternative to conventional ROSE, minimising the resource required from cytopathology services and improving patient care and access to best practice.image

The study aimed to demonstrate rapid and effective molecular testing on liquid-based cytology (LBC) samples for EGFR, KRAS and BRAF mutations using the Biocartis Idylla™. Rapid on-site evaluation (ROSE) LBC samples for patients with non-small cell lung carcinoma (NSCLC) or pancreatic ductal adenocarcinoma (PDAC) were tested for EGFR, KRAS and BRAF mutations based on the relevance to tumour subtype. The quantification values (Cq values) and mutation detection status were compared between LBC samples and routine formalin-fixed paraffin-embedded (FFPE) clot samples. ROSE LBC samples (n = 54) showed a higher yield of well-preserved tumour and wild type (WT) DNA, demonstrated by lower quantification cycles, no false positives or false negatives, and a higher sensitivity for low allele frequency mutations when compared with FFPE clot samples. The Biocartis Idylla™ provides highly sensitive, reliable and rapid testing for LBC samples for the detection of EFGR and KRAS mutations. BRAF mutations were not detected in the participant cohort; however, all LBC WT BRAF results correlated with the results from the FFPE clot samples. Access to rapid molecular testing using LBC samples can detect the most frequent driver mutations closer to the time of diagnosis, enabling the selection of the most effective first-line targeted therapy sooner, reducing delays or side effects from suboptimal treatments, patient anxiety and costs to healthcare systems, whilst improving patient outcomes.

No standardised, comprehensive approach to Rapid On‐Site Evaluation (ROSE) of cytology samples currently exists. Recent meta‐analysis indicates variation in the effectiveness of ROSE [1], however, reviews commonly omit the details of how ROSE is conducted. This review demonstrates the clinical effectiveness of Single Slide Assessment (SSA) for ROSE of cytology samples, providing a highly effective, standardised methodology, maximising cell yield and the diagnostic potential of samples obtained via Endobronchial or Endoscopic ultrasound (EBUS/EUS). Advances in molecular testing and immunotherapy now allow patients to access sophisticated, targeted cancer treatments and consequently, obtaining diagnostic material alone is no longer sufficient. SSA uses specific criteria, based on the morphological presentation, to ensure sufficient amounts of material are obtained through one procedure, allowing for all the molecular profiling and tumour expression testing required to provide the patient and clinicians with the optimal treatment options. 450 EUS/EBUS procedures were conducted with ROSE SSA performed by a biomedical scientist (BMS) between 2010 and 2017. In 97% of cases, ROSE SSA matched the final report (inadequate vs adequate – benign material vs malignancy). In 200/208 cases (96%) ROSE SSA provided sufficient material for immunocytochemistry and in 92% (85/92) of cases, ROSE SSA provided sufficient material for additional molecular testing / tumour profiling. The median number of needle passes was three. ROSE SSA streamlines diagnostic pathways; minimising risk of complications to patients, reducing cost and delays to treatment associated with repeat or more invasive procedures. Using SSA, sufficient material for a comprehensive diagnosis can be obtained in one procedure.