Acta Cytologica最新文献

{"title":"The Cytopathology of Infectious Disease: A Review.","authors":"Pamela Michelow, Charlotte Sriruttan-Nel","doi":"10.1159/000553052","DOIUrl":"10.1159/000553052","url":null,"abstract":"<p><strong>Background: </strong>Infectious diseases continue to represent a major global burden, remaining among the leading causes of morbidity and mortality. Cytopathology is a valuable diagnostic tool across diverse healthcare settings, including both high-income and low- and middle-income countries for diagnosis of infection. Its cost-effectiveness and ability to provide rapid results make it particularly well suited for timely clinical decision-making, which can be critical and, in some cases, lifesaving in a patient with an infectious disease. While cytopathology often yields sufficient information for diagnosis, confirmatory ancillary techniques, such as microbiological studies, immunocytochemistry, and molecular assays, may be necessary in selected cases to establish a definitive diagnosis.</p><p><strong>Summary: </strong>The practicing cytopathologist and cytologist must be familiar with the cytomorphologic diagnosis of infection. This review article highlights the cytomorphologic features of infectious diseases that can be diagnosed cytologically, the utility of ancillary tests, and discusses both the advantages and limitations of cytopathology in this context.</p><p><strong>Key message: </strong>Careful and systematic attention to cytomorphologic features, including both the infectious agents and the characterisation of the host tissue response, together with clinicoradiologic correlation and the judicious application of ancillary diagnostic tests, is essential for achieving an accurate diagnosis of infection. Such an integrated approach minimises the risk of false-negative and false-positive interpretations, ensures specimens are appropriately classified within the correct cytologic reporting category, and facilitates informed decisions regarding the selection of ancillary investigations.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-19"},"PeriodicalIF":1.5,"publicationDate":"2026-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148256907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of a Storage Method for Peritoneal and Pleural Effusion Cytology Specimens for Long-Term Preservation of Antigenicity in Immunocytochemical Staining.","authors":"Dai Yamaguchi, Ken-Ichi Mukaisho, Naoko Taniura, Akiko Harada, Muneo Iwai, Machiko Tanimura, Yuji Hayashi, Suzuko Moritani, Ryoji Kushima","doi":"10.1159/000552980","DOIUrl":"10.1159/000552980","url":null,"abstract":"<p><strong>Introduction: </strong>Additional immunocytochemical staining is frequently required in routine cytodiagnosis to refine presumptive diagnoses. However, optimal conditions for preserving antigenicity in cytological specimens over time remain unclear. This study evaluated the effects of preparation method, storage temperature, and storage duration on antigen preservation in clinical cytology specimens and cultured malignant tumor cells.</p><p><strong>Methods: </strong>Residual sediments from 12 pleural or ascitic fluid cytology specimens were fixed in BD CytoRich Red for 1 h and processed using the SurePath liquid-based cytology method. Immunocytochemical staining performed immediately after preparation served as the baseline control. Specimens were stored as glass smears or in preservative fluid at 4°C or -20°C for 1 week, 1 month, or 3 months. Ki-67 and calretinin were used as primary antibodies. To reflect routine cytology practice, Papanicolaou-stained (Pap-stained) preparations were also included. Cultured malignant tumor cell lines (TCC-Meso-1, MCF-7, and KATO-III) were prepared as Pap-stained, coverslipped slides, and stored at room temperature.</p><p><strong>Results: </strong>In clinical glass smears, neither Ki-67 nor calretinin showed a significant decline compared with baseline across storage conditions. In preservative fluid, Ki-67 positivity differed from glass smears and was associated with storage temperature; 4°C storage resulted in significant reductions from 1 week onward. At -20°C, reductions were limited, although selected short-term comparisons with baseline reached statistical significance. In clinical Pap-stained preparations, Ki-67 showed a significant time-dependent decrease evident at 3 months, with a similar pattern observed for calretinin. In FDR-adjusted comparisons with the non-stored baseline, Pap-stained samples exhibited the greatest reductions in rate ratios, whereas most cooled non-Pap preparations retained relatively preserved immunopositivity. In cultured Pap-stained cell preparations, Ki-67 reductions were modest and tumor type-related, with no decrease observed in TCC-Meso-1 cells.</p><p><strong>Conclusion: </strong>Fixation followed by glass smear preparation and low-temperature storage (4°C or -20°C) allows relatively stable preservation of Ki-67 and calretinin immunoreactivity. Storage at -20°C may be preferable when longer preservation periods are required. In contrast, delayed immunocytochemical staining of Pap-stained specimens may result in tumor type-related variability in Ki-67 immunoreactivity and therefore should be interpreted with caution.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-12"},"PeriodicalIF":1.5,"publicationDate":"2026-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148222462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diagnostic Utility of Endoscopic Crush Cytology in Gastrointestinal Malignancies.","authors":"Dinesh Kumar Ambati, Pooja K Suresh, Rakshatha Nayak, Hema Kini, Jyoti R Kini, Sridevi H Basavaiah, Ranjita Devi Chongtham, Akhil Kocherlakota","doi":"10.1159/000552792","DOIUrl":"10.1159/000552792","url":null,"abstract":"<p><strong>Introduction: </strong>Gastrointestinal (GI) cancers represent one of the most pressing global public health challenges, accounting to nearly one-third of all cancer-related mortality worldwide. Cytological evaluation allows rapid interpretation and triaging of material. Crush cytology is an added asset to histology to maximize diagnostic accuracy and accelerate decision-making for the management of these lesions. This study aimed to assess the diagnostic utility of endoscopic crush cytology in GI tract lesions.</p><p><strong>Methods: </strong>A cross-sectional observational study was conducted on GI crush cytology samples received at department of pathology from January 2019 to December 2024. These cases were cytologically categorized across various GI sites as follows, negative for malignancy, atypical favors reactive, atypical suspicious for malignancy and positive for malignancy. The corresponding biopsy slides were reviewed and documented. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated.</p><p><strong>Results: </strong>During the study period, we reviewed 303 cases of GI crush cytology. The mean age at presentation was 60 years (age range: 17-90 years) with a male-to-female ratio of 2:1. These cases were categorized into lower GI with 151 (49.8%) cases and upper GI with 152 (50.2%) cases. The most common site of involvement was colorectal with 146 (48.2%) cases followed by gastric region with 58 (19.1%) cases and esophagus with 31 (10.2%) cases. Negative for malignancy accounts for 7 (2.3%) cases, atypical favors reactive accounts for 120 (39.6%) cases, atypical suspicious for malignancy accounts for 4 (1.3%) cases, and positive for malignancy accounts for 172 (56.8%) cases across the GI region. Histopathology correlation was available in 179 (59.1%) cases. The overall GI crush cytology sensitivity was 96.1%, specificity was 96.2%, PPV was 98.4%, NPV was 90.9% and the diagnostic accuracy was 96.1%. The Youden's index was 0.9222, and the p value was <0.001 (χ2).</p><p><strong>Conclusion: </strong>Crush cytology is a highly sensitive, specific, rapid, and cost-effective technique for diagnosing GI malignancies in endoscopically suspected malignant lesions. It is a valuable complement to histology, enhancing diagnostic accuracy and accelerating decision-making to manage these lesions. The present study highlights the significant diagnostic utility of crush cytology by demonstrating high sensitivity, specificity, and diagnostic accuracy, particularly in detecting adenocarcinomas and squamous cell carcinomas.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-15"},"PeriodicalIF":1.5,"publicationDate":"2026-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13395394/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148203704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Illuminating the Past to Understand the Present: The Life and Legacy of Ruth Moore Graham.","authors":"Joy M Hoang, Güliz A Barkan","doi":"10.1159/000552777","DOIUrl":"10.1159/000552777","url":null,"abstract":"","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-4"},"PeriodicalIF":1.5,"publicationDate":"2026-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148194321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrating Morphology and Molecular Biology: Artificial Intelligence-Driven Molecular Prediction in Pathology with a Focus on Cytology.","authors":"Diana Montezuma, Fernando C Schmitt","doi":"10.1159/000552799","DOIUrl":"10.1159/000552799","url":null,"abstract":"<p><strong>Background: </strong>Recent computational pathology research proposes using artificial intelligence (AI) to infer molecular features from routine haematoxylin-eosin images, aiming to reduce the cost and time associated with biomarker analysis.</p><p><strong>Summary: </strong>Herein, we explore advancements in predicting genetic mutations, molecular subtypes, microsatellite instability, tumour mutational burden, and spatial proteomics from histological and, specifically, cytological specimens. Despite some promising predictive performances, recent evidence also suggests that current models may rely on confounding clinicopathological features or \"shortcut learning\" rather than true biological signals, raising important questions about their consistency when applied to broader and more diverse patient cohorts. In cytology, the field is at an earlier stage, and although AI-based molecular triage is an appealing concept, further research is needed to determine whether the predictive performance observed in histology can be replicated in cytological specimens.</p><p><strong>Key messages: </strong>AI-based prediction of molecular features from histology shows promise but remains insufficient to replace established molecular testing. Current models may be influenced by shortcut learning and therefore require validation across broader cohorts. In cytology, AI-driven molecular prediction is still preliminary and warrants substantial further investigation.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-9"},"PeriodicalIF":1.5,"publicationDate":"2026-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148161323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Indeterminate Bethesda System Category (Bethesda Category III) Thyroid Nodules: Cytomorphologic Subclassification and Its Impact on Malignancy Risk.","authors":"Rinë Limani, Zgjim Limani, Shkelzen Reçica, Labinota Kondirolli, Etnik Bajraktari, Brikenë Blakaj Gashi, Drita Miftari Pazhari","doi":"10.1159/000552791","DOIUrl":"10.1159/000552791","url":null,"abstract":"<p><strong>Introduction: </strong>Bethesda category III thyroid cytology (atypia of undetermined significance [AUS]) represents a diagnostically diverse category with variable malignancy risk. Cytomorphologic subclassification may improve risk stratification.</p><p><strong>Methods: </strong>We performed a retrospective study of Bethesda category III thyroid nodules from a tertiary-care center. Cases were subclassified according to the predominant cytomorphologic atypia (architectural, nuclear, oncocytic, and cystic/inflammatory). Where available, cytologic findings were correlated with surgical histopathology. Malignancy rates were calculated for both definitively linked cytology-histology cases and all surgically treated nodules.</p><p><strong>Results: </strong>Of 1,872 thyroid fine-needle aspiration procedures performed between 2013 and 2022, 243 nodules (13.0%) were classified as Bethesda category III. Architectural atypia was the most common subtype (44.4%), followed by nuclear atypia (29.2%), cystic/inflammatory atypia (14.9%), and oncocytic atypia (11.5%). Surgical resection was performed in 186 cases, with definitive cytology-histology correlation established in 136. Malignancy was identified in 41.9% of definitively linked cases. Nuclear atypia demonstrated the highest malignancy rate (68.3%), significantly higher than architectural atypia (32.3%) (OR 4.52; 95% CI 1.94-10.54; p < 0.001). Papillary thyroid carcinoma was the predominant malignant diagnosis.</p><p><strong>Conclusion: </strong>Cytomorphologic subclassification of Bethesda category III (AUS) thyroid nodules identifies nuclear atypia as the strongest predictor of malignancy. Incorporation of cytomorphologic subclassification into routine reporting may improve risk stratification and clinical decision-making in Bethesda category III nodules. Malignancy rates varied substantially according to denominator definition, highlighting the impact of case selection on risk estimation.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-9"},"PeriodicalIF":1.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148142432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clinical Utility of Cytology with Ancillary Testing in the Management of Patients with Pancreaticobiliary Lesions.","authors":"Martha B Pitman, Barbara A Centeno, Michelle D Reid","doi":"10.1159/000552736","DOIUrl":"10.1159/000552736","url":null,"abstract":"<p><strong>Background: </strong>The cytological diagnosis of pancreaticobiliary (PB) lesions is fraught with challenges. Diagnostic specificity is high, but sensitivity suffers from a high threshold for a definitive diagnosis of malignancy. Ancillary testing using immunohistochemical stains, biochemical analysis, and genetic testing have greatly improved diagnostic accuracy of cytology and small biopsy samples of PB lesions.</p><p><strong>Summary: </strong>This review of the cytomorphology and helpful ancillary tests for the diagnosis of the commonly encountered PB lesions offers a practical approach for the practicing pathologist.</p><p><strong>Key messages: </strong>The differential diagnosis of pancreatic lesions is initially divided into two groups based on imaging: solid versus cystic. Solid masses are the most common lesion, and pancreatic ductal carcinoma is the most common malignancy. Although most cases of adenocarcinoma can be diagnosed on morphology alone, ancillary tests such as immunohistochemical stains of p53, SMAD4/DPC4, and p16 can add support for challenging cases. The clinical questions for the evaluation of a pancreatic cyst are twofold: is the cyst mucinous, and if so, is it high risk for malignancy? Biochemical and molecular testing are ancillary tests that help answer these questions. Bile duct strictures are evaluated with brushing cytology to assess for malignancy. Molecular analysis is an important ancillary test to assist in overcoming the low sensitivity of cytology given the high threshold for the cytological diagnosis of malignancy. A multimodal approach using clinical and imaging information, cytomorphology, and ancillary testing is the key to accurate diagnosis in all three scenarios.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-27"},"PeriodicalIF":1.5,"publicationDate":"2026-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148051842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of the World Health Organization Reporting System for Lung Cytopathology: Risk of Malignancy and Overall Survival in Fine-Needle Aspiration Biopsies.","authors":"Awab Abdalhai, Wen-Yu Hsiao, Qun Wang","doi":"10.1159/000552703","DOIUrl":"10.1159/000552703","url":null,"abstract":"<p><strong>Introduction: </strong>The World Health Organization (WHO) Reporting System for lung cytopathology provides a 5-tiered diagnostic framework. However, validation of the associated risk of malignancy (ROM) and clinical outcomes remains limited. This study evaluated the performance of the WHO reporting system by assessing ROM and overall survival (OS) in lung fine-needle aspiration biopsies (FNAB) specimens.</p><p><strong>Methods: </strong>A retrospective review of the institutional pathology database identified patients who underwent endobronchial ultrasound-guided transbronchial FNAB or transthoracic CT-guided FNAB for lung lesions between January 2015 and June 2022. All cases were recategorized according to the WHO reporting system. Absolute ROM was determined by histologic and/or clinical follow-up of at least 6 months and compared with published studies that used the WHO and other international reporting systems. OS rates were analyzed across diagnostic categories.</p><p><strong>Results: </strong>A total of 1,038 FNAB cases were included. The ROM for each WHO diagnostic category was as follows: insufficient/inadequate/nondiagnostic, 19%; benign, 9%; atypical, 33%; suspicious for malignancy, 84%; and malignant, 100%. These findings demonstrated overall concordance with prior studies, with comparatively lower ROMs in the insufficient/inadequate/nondiagnostic, benign, and atypical categories, and upper range ROMs in the suspicious for malignancy and malignant categories. Immunocytochemistry and molecular testing performed on available cell block materials supported tumor subtyping and therapeutic decision-making.</p><p><strong>Conclusions: </strong>Application of the WHO reporting system significantly improves stratification of ROM and OS across diagnostic categories in lung FNAB specimens. Inclusion of a benign category and reclassification of low-grade carcinomas as malignant enhance diagnostic precision and support optimized patient management.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-11"},"PeriodicalIF":1.5,"publicationDate":"2026-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148051815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benign Normal Tissue Mimicking Neoplastic Disorders: A Cytopathological Review.","authors":"Philippe Stephenson, María Luisa C Policarpio-Nicolas, Xiaoqi Lin, Guoping Cai, José A Jiménez-Heffernan","doi":"10.1159/000552739","DOIUrl":"10.1159/000552739","url":null,"abstract":"<p><strong>Background: </strong>Knowledge of normal morphology is an essential prerequisite for interpreting pathological changes. We are very familiar with normal tissue histology, which is already taught in medical schools. In contrast, information on the normal appearance of tissue in cytological specimens, particularly fine-needle aspiration biopsy (FNAB), is not widely available. A lack of familiarity with normal cytology is an easily avoidable source of diagnostic errors or difficulties. This is especially true during rapid on-site evaluation (ROSE), where misinterpretation of normality can lead to the procedure being finished prematurely. In addition, there are tissues whose normal cytomorphology is rarely seen and with which pathologists and cytotechnicians are largely unfamiliar. In addition to its significant practical utility, normal cytomorphology constitutes an important independent field of knowledge within the realm of diagnostic cytopathology.</p><p><strong>Summary: </strong>A review has been conducted of situations in which cytological normality can lead to diagnostic confusion. The review discusses the most well-known and frequent potential errors, such as those related to the bronchial, duodenal, and gastric mucosa (echoendoscopic FNAB), mesothelium, liver, pancreas, bone marrow, cerebellum, etc. In addition, we have emphasized the more complex cases, even if they are rare. Among these are the spleen, kidney, neural ganglia, seminal vesicle, testis, and pineal gland.</p><p><strong>Key messages: </strong>There are several reasons why understanding normal cytomorphology is becoming increasingly important. During the sampling of small tumors, the needle frequently penetrates the surrounding parenchyma, aspirating normal tissue cells. FNAB of deep and technically complex lesions increases the likelihood of contamination from surrounding tissues. In addition, the emergence of new approaches such as echoendoscopy involves examining tissues that were rarely seen before. If we add this to the speed required during ROSE, the need for an in-depth understanding of normal cytomorphology becomes obvious. Given the wide variety of tissues, a general analysis is not possible; it must be conducted on an individual basis. In any case, cytomorphology of normal tissues is typically striking and characteristic, which facilitates their recognition. This review aimed to assist by presenting common and uncommon normal morphology and key points for specific recognition.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-13"},"PeriodicalIF":1.5,"publicationDate":"2026-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148004155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Real-World Impact of the 2023 Bethesda System on Thyroid Fine-Needle Aspiration Category Distribution: A Multiphase Longitudinal Study from Algeria.","authors":"Abderrahmane Yahia Cherif, Manel Boudouaya","doi":"10.1159/000552737","DOIUrl":"10.1159/000552737","url":null,"abstract":"<p><strong>Introduction: </strong>The third edition of the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC, 2023) introduced refinements in the criteria for indeterminate thyroid lesions. Observed temporal shifts in cytological categories may reflect both classification changes and evolving technical and interpretive practices. This study evaluated the relative contributions of these factors in a real-world hospital setting.</p><p><strong>Methods: </strong>We conducted a retrospective study of 731 ultrasound-guided thyroid fine-needle aspiration specimens at a public referral center in western Algeria across four periods: 2017, 2021, 2024, and 2025. Cases from 2017 to 2021 were reported using TBSRTC 2017, while 2024-2025 cases used TBSRTC 2023. Category distributions were compared using chi-square and two-proportion z-tests (p < 0.05).</p><p><strong>Results: </strong>Overall category distribution differed significantly over time (χ2 = 61.0, p < 0.0001). Nondiagnostic (category I) rates declined from 20.5% in 2017 to 7.8% in 2021 (p < 0.001), reflecting technical improvements, and remained stable thereafter (11.7-12.3%). AUS/FLUS (category III) rates were stable (4.9-7.1%; p > 0.3). Category IV (FN/SFN) transiently increased in 2021 (20.4%) before stabilizing post-2023 implementation (3.1-5.1%; p < 0.0001 for 2021 vs. 2024). Categories V-VI remained consistently low (≤4.9% and ≤0.4%, respectively) without evidence of systematic under-calling.</p><p><strong>Conclusion: </strong>Temporal variations in thyroid cytology reflected the combined effects of technical maturation, institutional adaptation, and classification updates rather than TBSRTC 2023 alone. Multiphase longitudinal analyses are critical to separate these influences when evaluating revised reporting systems, particularly in resource-limited settings. Implementation of structured protocols - including case validation training sets, double reading periods for indeterminate categories, and ROSE adoption is recommended to minimize transitional variability during adoption of revised classification systems.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-8"},"PeriodicalIF":1.5,"publicationDate":"2026-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148004128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}