Papanicolaou Society Research Articles

Papanicolaou Society of Cytopathology System vs World Health Organization of Reporting System for Pancreaticobiliary Cytopathology‐Comparison of Risk of Malignancy and Diagnostic Predictive Values: A 3 Year Retrospective Study in India

Papanicolaou Society of Cytopathology System vs World Health Organization of Reporting System for Pancreaticobiliary Cytopathology‐Comparison of Risk of Malignancy and Diagnostic Predictive Values: A 3 Year Retrospective Study in India

Are we ready to bridge classification systems? A comprehensive review of different reporting systems in thyroid cytology.

The evaluation of thyroid lesions is common in the daily practice of cytology. While the majority of thyroid nodules are benign, in recent decades, there has been increased detection of small and well-differentiated thyroid cancers. Combining ultrasound evaluation with fine-needle aspiration cytology (FNAC) is extremely useful in the management of thyroid nodules. Furthermore, the adoption of specific terminology, introduced by different thyroid reporting systems, has helped effectively communicate thyroid FNAC diagnoses in a clear and understandable way. In 1996, the Papanicolaou Society thyroid cytological classification was introduced. This was followed in 2005 by the first Japanese and then in 2007 by the Bethesda System for Reporting Thyroid Cytopathology, which subsequently underwent two revisions. Other international thyroid terminology classifications include the British, Italian, Australasian and other Japanese cytology systems. This review covers similarities and differences among these cytology classification systems and highlights key points that unify these varied approaches to reporting thyroid FNAC diagnoses.

Risk of malignancy and overall survival associated with the diagnostic categories in the World Health Organization Reporting System for Pancreaticobiliary Cytopathology.

The World Health Organization (WHO) classification system revised the Papanicolaou Society of Cytopathology (PSC) system for reporting pancreaticobiliary cytopathology. To better stratify intraductal and/or cystic neoplasms by cytologic grade, the neoplastic, other category was replaced by two new categories: pancreaticobiliary neoplasm, low-risk/grade (PaN-Low) and pancreaticobiliary neoplasm, high-risk/grade (PaN-High). Low-grade malignancies were placed in the malignant category, and benign neoplasms were placed in the benign/negative for malignancy category. An institutional pathology database search identified patients who underwent endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for pancreatic lesions from January 2015 to April 2022. The absolute risk of malignancy (ROM) was determined by histologic and/or clinical follow-up of at least 6 months, and overall survival rates were calculated across diagnostic categories, comparing the WHO and PSC systems. In total, 1012 cases were reviewed and recategorized. The ROM for the WHO system was 8.3% for insufficient/inadequate/nondiagnostic, 3.2% for benign/negative for malignancy, 24.6% for atypical, 9.1% for PaN-Low, 46.7% for PaN-High, 75% for suspicious for malignancy, and 100% for malignant. Comparatively, the ROM for the PSC system was 7.4% for nondiagnostic, 3.0% for negative for malignancy, 23.1% for atypical, 0% for neoplastic, benign, 7.3% for neoplastic, other, 75% for suspicious for malignancy, and 100% for malignant. The WHO system demonstrated superior stratification for overall survival. The WHO system significantly improves the stratification of ROM and overall survival across diagnostic categories by introducing the PaN-Low and PaN-High categories and reassigning low-grade malignancies to the malignant category. Analyzing EUS-FNA samples with the WHO system provides critical insights for guiding clinical management.

The Papanicolaou Society of Cytopathology System for Reporting Respiratory Cytology: To Establish Efficacy and Ease to Use in Routine Cytology Practice

Background: Various pulmonary cytology techniques have been established, representing morphological diversity and ranging from non-invasive to minimally invasive. However, there is currently no widely accepted classification system for respiratory cytology. In 2016, the Papanicolaou Society of Cytopathology (PSC) proposed a six-tiered category system for the cytological sample obtained from the respiratory tract. The diagnostic efficacy of such a category system can help in the early diagnosis of lung cancer patients, thereby reducing mortality and morbidity. Aim: The aim of this study was to determine the diagnostic accuracy and utility of PSC guidelines for reporting respiratory cytology specimens in comparison to histopathology. Materials and Methods: This study was conducted over 6 months, from September 2023 to February 2024, on a prospective basis. Out of a total of 165 samples analyzed, 147 (89%) were bronchoalveolar lavage samples, 09 (05%) were bronchial brushings, 03 (02%) were bronchial washings, and 06 (04%) were endobronchial ultrasound-guided transbronchial fine-needle aspiration. These cytological specimens were processed and categorized according to the PSC reporting system for respiratory cytology, as non-diagnostic, benign, atypical, neoplastic (benign/undetermined malignant potential), suspicious of malignancy, and malignant. In all cases, the histopathological correlation with corresponding transbronchial or endobronchial lung biopsy was done. Results: Our study found that 4% of the cases were non-diagnostic, 80% were benign, 13% were atypical, 2% were suspicious for malignancy, and 1% were malignant. When compared with the histological diagnosis, the sensitivity was 53.13%, the specificity was 93.23%, and the overall accuracy was 85.45%. Conclusion: The PSC reporting system for respiratory cytology can easily standardize reporting patterns to enhance communication between cytopathologists and clinicians, ultimately improving patient care.

Reproducibility assessment of WHO reporting system for pancreaticobiliary cytopathology: A single institution experience.

The World Health Organization (WHO) reporting system for pancreaticobiliary cytopathology was released to internationalize the reporting, assisting in correct diagnosis and patient treatment with significant revisions from the previous Papanicolaou Society of Cytopathology (PSC) system. The "neoplastic: benign" and "neoplastic: other" categories have mostly been superseded by two new ones: "pancreatic neoplasia-low-grade" (PaN-low) and "pancreatic neoplasia-high-grade" (PaN-high), which classify intermediate neoplastic lesions based on cytological atypia. We aim to assess the reproducibility and risk of malignancy (ROM) for reporting pancreaticobiliary cytopathology by the WHO system in comparison with the PSC system. A retrospective study by reviewing archival slides sent for pancreaticobiliary cytological evaluation from June 2021 to June 2023, by two pathologists blinded to each other's findings. Absolute ROM was determined by histopathology/cell block study/clinical follow-up (minimum 6 months)/overtly malignant imaging/metastasis. A total of 332 cases from 329 patients met the inclusion criteria, comprising pancreatic, gallbladder, and biliary lesions. The median patient age was 54 years (range, 14-86 years). The overall sensitivity of the test is 74.9% specificity is 93.2%, positive predictive value of 96.8%, negative predictive value of 57.6%, and a diagnostic accuracy of 81.8%. The absolute ROM for each site in all categories was comparable with that of the published data from the WHO system. Our study highlights the reliability of the WHO system for guiding clinical decision-making and patient management in the context of pancreaticobiliary. However, continual efforts among pathologists are essential to maintain consistent accuracy in cytological interpretations.

The World Health Organization Reporting System for Pancreaticobiliary Cytopathology: Overview and Summary.

The recently published WHO Reporting System for Pancreaticobiliary Cytopathology (World Health Organization [WHO] System) is an international approach to the standardized reporting of pancreaticobiliary cytopathology, updating the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology (PSC System). Significant changes were made to the categorization of benign neoplasms, intraductal neoplasms, mucinous cystic neoplasms, and malignant neoplasms considered low grade. Benign neoplasms, such as serous cystadenoma, categorized as Neoplastic: benign in the PSC system, are categorized as Benign/negative for malignancy in the WHO system. Pancreatic neuroendocrine tumor, solid-pseudopapillary neoplasm, and gastrointestinal stromal tumor, categorized as Neoplastic: other in the PSC system, are categorized as Malignant in the WHO System in accord with their classification in the 5th edition WHO Classification of Digestive System Tumours (2019). The two new categories of Pancreaticobiliary Neoplasm Low-risk/grade and Pancreaticobiliary Neoplasm High-risk/grade are mostly limited to intraductal neoplasms and mucinous cystic neoplasms. Low-risk/grade lesions are mucinous cysts, with or without low-grade epithelial atypia. High-risk/grade lesions contain neoplastic epithelium with high-grade epithelial atypia. Correlation with clinical, imaging, and ancillary studies remains a key tenet. The sections for each entity are written to highlight key cytopathological features and cytopathological differential diagnoses with the pathologist working in low resource setting in mind. Each section also includes the most pertinent ancillary studies useful for the differential diagnosis. Sample reports are provided for each category. Finally, the book provides a separate section with risk of malignancy and management recommendations for each category to facilitate decision-making for clinicians.

Second opinion for pulmonary and pleural cytology is valuable for patient care

IntroductionThoracic cytology can be challenging due to limited procured material or overlapping morphology between benign and malignant entities. In such cases, expert consultation might be sought. This study aimed to characterize all pulmonary and pleural cytology consult cases submitted to our practice and provide recommendations on approaching difficult cases. Materials and MethodsAll thoracic (pulmonary and pleural) cytology cases submitted for expert consultation to the University of Michigan (MLabs) from 2013 to mid-2022 were reviewed. Cases where cytology was only part of a hematopathology or surgical pathology consult were excluded. Patient demographics, specimen location, procedure performed, referring diagnosis, and our diagnoses were recorded for each case. Diagnoses were categorized according to the Papanicolaou Society of Cytopathology recommendations for pulmonary and effusion cytology. Discordant diagnoses were stratified as major or minor. Data was analyzed using Chi-Square analysis and logistic models. ResultsWe received 784 thoracic cytology consult cases, including 530 exfoliative samples and 307 fine needle aspirations (FNAs). The most common anatomic locations sampled were the bronchial wall (n=194, 23%), lung nodule (n=322, 38%), and pleura (n=296, 35%). 413 cases had a diagnostic discrepancy (48.3%), with 274 (66%) minor and 139 (34%) major discrepancies. By location, pleural effusion specimens had the highest probability of a discrepant diagnosis (p=0.003). By specimen type, FNA samples were significantly more likely to have a discrepant diagnosis (p=0.06). ConclusionNearly half of the thoracic cytology cases submitted for expert second opinion had diagnostic discrepancies. Consequently, consulting a tertiary medical care center with cytopathology expertise for challenging thoracic cytology diagnoses is beneficial.

The current state of digital cytology and artificial intelligence (AI): global survey results from the American Society of Cytopathology Digital Cytology Task Force

The integration of whole slide imaging (WSI) and artificial intelligence (AI) with digital cytology has been growing gradually. Therefore, there is a need to evaluate the current state of digital cytology. This study aimed to determine the current landscape of digital cytology via a survey conducted as part of the American Society of Cytopathology (ASC) Digital Cytology White Paper Task Force. A survey with 43 questions pertaining to the current practices and experiences of WSI and AI in both surgical pathology and cytology was created. The survey was sent to members of the ASC, the International Academy of Cytology (IAC), and the Papanicolaou Society of Cytopathology (PSC). Responses were recorded and analyzed. In total, 327 individuals participated in the survey, spanning a diverse array of practice settings, roles, and experiences around the globe. The majority of responses indicated there was routine scanning of surgical pathology slides (n = 134; 61%) with fewer respondents scanning cytology slides (n = 150; 46%). The primary challenge for surgical WSI is the need for faster scanning and cost minimization, whereas image quality is the top issue for cytology WSI. AI tools are not widely utilized, with only 16% of participants using AI for surgical pathology samples and 13% for cytology practice. Utilization of digital pathology is limited in cytology laboratories as compared to surgical pathology. However, as more laboratories are willing to implement digital cytology in the near future, the establishment of practical clinical guidelines is needed.

Reporting Pancreatic FNAC using the Papanicolaou System: Still a Diagnostic Challenge.

The Papanicolaou Society of Cytopathology System for reporting Pancreaticobiliary Cytology (PSCPC) is a reliable method to classify pancreatic fine needle aspiration cytology (FNAC) smears. However, it is not without practical problems which can diminish the diagnostic accuracy of the cytological diagnosis. To determine the diagnostic pitfalls while reporting cytomorphology of pancreatic lesions according to PSCPC on correlating FNAC findings with histopathology. Retrospective analysis of pancreatic FNAC smears received in the Department of Pathology of our tertiary care institute over a period of 2 years was done. The cytological diagnoses were classified according to the Papanicolaou Society of Cytopathology system of reporting pancreaticobiliary cytology and correlated with histopathology. The reasons of cyto-histological discordance were analyzed. Out of 50 cases in which both FNAC and biopsy of pancreatic lesions were done, 34 cases were positive/malignant (Category VI), eight cases were suspicious for malignancy (Category V), three cases were neoplastic (Category IV), two cases were atypical (Category III), two cases were negative for malignancy (Category II), and one case was non-diagnostic (Category I). Out of 50 cases, histopathology was non-diagnostic due to inadequate material in six cases. The cytological diagnoses were compared with histopathology in the remaining 44 cases. Categories III, IV V, and VI were considered as positive for neoplastic pathology. The sensitivity of FNAC to predict neoplastic pathology was 97.5%, while the specificity was 25%. The positive predictive value was 92.9%. Two cases reported as atypical (Category III) turned out to be adenocarcinoma on histopathology. One case reported as neuroendocrine tumor and two cases reported as adenocarcinoma on cytology displayed features of chronic pancreatitis on histology. One case reported as neoplastic mucinous cyst (Category IV) turned out to be adenocarcinoma on histology (limited concordance). The cytopathologist needs to be wary of the potential pitfalls to improve the diagnostic accuracy of FNACs.

The World Health Organization Reporting System for Pancreaticobiliary Cytopathology.

The World Health Organization (WHO) Reporting System for Pancreaticobiliary Cytopathology (WHO System) is the product of a joint venture between the World Health Organization, the International Academy of Cytology, and the International Agency for Research on Cancer. The WHO System revises the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology (PSC System) and replaces the 6-tiered system with a 7-tiered system. To explain the WHO System and the differences with the PSC System. The WHO System and the PSC System of Reporting Pancreaticobiliary Cytopathology. The diagnostic categories of the WHO System are "Insufficient/Inadequate/Nondiagnostic"; "Benign (Negative for Malignancy"'; "Atypical"; "Pancreaticobiliary Neoplasm, Low Risk/Low Grade (PaN-Low)"; "Pancreatic Neoplasm, High Risk/High Grade (PaN-High)"; "Suspicious for Malignancy"; and "Malignant." In the WHO System, the "benign" category includes both nonneoplastic and neoplastic lesions, so the "Neoplastic: Benign" category of the PSC system has been eliminated. Low-grade malignancies, pancreatic neuroendocrine tumors (PanNETs), and solid-pseudopapillary neoplasm (SPN) classified as "Neoplastic: Other" in the PSC System are classified as "Malignant" in the WHO System, leaving in the "Neoplasm" category intraductal lesions, which are divided into 2 new diagnostic categories: "Pancreaticobiliary Neoplasm (PaN)-Low Risk/Grade" and "PaN-High Risk/Grade." As with the PSC System, the WHO System advocates close correlation with imaging and encourages incorporation of ancillary testing into the final diagnosis, such as biochemical (carcinoembryonic antigen [CEA] and amylase) and molecular testing. The WHO System includes risk of malignancy per category, and reporting and diagnostic management options that recognize the variations in resources of low- and middle-income countries.

Comparison of risk of malignancy and predictive value of diagnostic categories defined by Papanicolaou Society of Cytopathology system and WHO reporting system for pancreaticobiliary cytopathology in solid pancreatic lesions.

The standardized diagnostic categories defined by the World Health Organization (WHO) reporting system support the interdisciplinary interpretation of cytological findings in the management of pancreatic cancer. To compare this classification to the Papanicolaou Society of Cytopathology (PSC) system in terms of predictive value and risk of malignancy (ROM) in solid pancreatic lesions. Retrospective cohort study. All consecutive patients with solid pancreatic lesions who underwent endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) sampling at the University of Szeged from 2014 to 2021 were retrospectively enrolled. The predictive value and ROM of cytological findings were determined with comparison to histologic outcome and/or clinical follow-up. A total of 521 EUS-FNAs were performed with a malignancy rate of 81.76%. In both classification systems, the absolute ROM of "non-diagnostic," "negative for malignancy," "atypical," "suspicious for malignancy," and "malignant" categories were 48.2%, 2.3%, 78.1%, 100.0%, and 99.4%, respectively. Despite the heterogeneous nature of the "neoplastic: other" category of the PSC system, the absolute ROM for solid lesions was 100%. Pancreatic neoplasm: high-risk/grade category including only two endosonographically solid cases of high-grade intraductal papillary mucinous neoplasms showed 100% ROM. There were no differences between PSC and WHO systems in sensitivity, specificity, and negative and positive predictive values: excluding the "atypical" category, these were 99.7%, 95.6%, 97.7%, and 99.5%, respectively. The "atypical" category considered benign resulted in a higher decrease in validity and negative predictive value, compared to "atypical" considered true malignant (93.6% vs 97.7% and 65.8% vs 97.7%). For solid pancreatic lesions, the WHO system was identical to the PSC system in terms of ROM and predictive values.

The WHO system versus the Papanicolaou society of cytopathology system for reporting pancreaticobiliary cytology for risk stratification-which is better?

Recently, the World Health Organization (WHO) has proposed a reporting system for pancreaticobiliary cytopathology. We applied this classification for pancreatic lesion samples by fine needle aspiration (FNA) and compared the results to the previous classification of the Papanicolaou Society of Cytopathology (PSC) system for risk stratification. The computerized database was searched for all pancreatic endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) and transabdominal ultrasound-guided FNA (TUS-FNA) samples from 2016 to 2020 and cases were reassigned as per the PSC and the WHO diagnostic categories. Cases with follow-up, clinicoradiological, and/or histopathology were included in the study. The risk of malignancy (ROM) was calculated across all diagnostic categories based on clinical data, imaging data, and histopathology wherever available. There were a total of 625 pancreatic FNA. In 230 cases, follow-up information was available which included 116 EUS and 114 TUS-FNA samples. The ROM for PSC categories I-VI was 40%, 19.7%, 28.6%, 57.1%, 94.7%, and 97.9% and for the WHO categories (I-VII), it was 60%, 21.3%, and 35.7%, not representative, not applicable, 94.7% and 94.9%. The overall sensitivity and specificity of PSC was 68.2% and 96.2% when categories V and VI were taken as positive and 78.9% and 93.3% for WHO when categories VI and VII were taken as positive. Pancreatic FNA samples reported as per the WHO system showed better sensitivity as compared to the PSC system resulting in better risk stratification and consequently better patient management. The overall high specificity and moderate sensitivity reaffirm the utility of FNA in pancreatic lesions.

Grading pancreatic adenocarcinomas on fine needle aspiration cytology. The outstanding issues.

The three-tier grading scheme described in "The Papanicolaou Society of Cytopathology (PSC) System for reporting Pancreaticobiliary Cytopathology" (TPSCRPBC) which remained unchanged following the WHO Reporting System for Pancreaticobiliary Cytopathology (WRPBC) was evaluated on pancreatic adenocarcinomas (PACs) reported on endoscopic ultrasound-guided fine needle aspiration cytology (EUS-FNAC). The Papanicolaou and May Grunwald Giemsa-stained smears from 116 cases of PACs were graded using the three-tier grading scheme laid down by TPSCRPBC/WRPBC. Cases exhibiting multiple grades were assigned primary, secondary and tertiary grades. Each case was assigned a grade score, either by adding the primary and secondary grades, by adding the primary and tertiary grades when the tertiary grade was 3 or by doubling the grade when only one grade existed. Necrosis was estimated semi-quantitatively. The inter-observer reproducibility in grading was evaluated using Kappa and Kendall's tau-c. Correlations between the various grades, the stage of the tumour and the amount of necrosis were assessed using Spearman rho and Kendall's tau-b. 31.89% of cases showed one grade, and 68.11% showed at least two grades. 16.38% showed three grades. The two commonest grade scores were 3 and 5. The inter-observer reproducibility for grading and grade scoring was satisfactory. A positive correlation was noted between the grades and the amount of necrosis. No significant correlation was found between the grades, grade scores and the stage of the tumours. The TPSCRPBC/WRPBC grading scheme can be suitably applied to PACs with good inter-observer reproducibility. Cases often show multiple grades in the same tumour.

Risk of malignancy assessment of the different cytologic categories in respiratory cytology samples according to the new guidelines of the Papanicolaou Society of Cytopathology.

Cytology is extremely important for diagnosis of lung carcinoma and the Papanicolaou Society of Cytopathology (PSC) had proposed a new classification system for respiratory cytology for better communication between physicians and better patient management. The objective of this study is to analyze our samples in accordance with this classification and to evaluate the diagnostic accuracy of various cytologic techniques and to assess the risk of malignancy. Eight hundred and twenty respiratory cytology specimens (FNA, BAL, washing, brushing, sputum) collected between 2019 and 2022 were classified according to the PSC system and the risk of malignancy was assessed for each category using follow-up surgical samples. Sensitivity, specificity, and accuracy rates were determined based on a categorial approach, according to a similar study. The data of 820 respiratory cytology specimens from 576 patients were analyzed. 2.6% of these were non-diagnostic, 64.1% were NM, 5% were AC, 0.4% were N-B-LG, 4% were SM and 23.9% were ML. The risk of malignancy for each diagnostic category were: 42.8% for non-diagnostic, 31.2% for NM, 43.9% for AC, 87.9% for SM, 94.3% for ML. Sensitivity and specificity was calculated using only the malignant cases considered as positive tests and was 45.57% and 97.34% respectively. Our results correlated with the PSC system, and it was considered useful in clinical practice. However, more studies should be performed to evaluate the usefulness of this system. The ROMs of each category and the impact of different techniques should be further studied.

Evaluation of the diagnostic efficacy of liquid-based cytology obtained via percutaneous ultrasound-guided fine-needle aspiration for pancreatic masses: a large tertiary center's 8-year experience.

There were limited data on the diagnostic efficacy of liquid-based cytology (LBC) for pancreatic tissues acquired by percutaneous ultrasound-guided fine-needle aspiration (US-FNA). This study aimed to evaluate the diagnostic value of LBC acquired via percutaneous US-FNA for pancreatic tumors compared with LBC combined with smear cytology (SC). A retrospective database search (January 2014 and February 2022) was performed for patients who underwent percutaneous US-FNA with both LBC and SC. Clinical and pathological data were collected from 298 patients; eventually, 251 cases met the inclusion criteria. Diagnostic accuracy, sensitivity (SEN), specificity (SPE), positive predictive value (PPV) and negative predictive value (NPV) were compared. Rapid on-site evaluation (ROSE) was not available in all cases. Based on the pancreaticobiliary cytology guidelines published by the Papanicolaou Society of Cytopathology, 224 (89.2%), 13 (5.2%) and 14 (5.6%) cases were diagnosed as malignant, pre-malignant and benign lesions, respectively. The diagnostic accuracy of the LBC + SC (88.5%) was better than that of LBC (87.3%) but without statistical significance (P = 0.125). The SEN, SPE, PPV and NPV were 87.5%, 85.2%, 98.0% and 45.1%, respectively, in the LBC group and 88.8%, 85.2%, 98.0% and 47.9%, respectively, in the LBC + SC group. According to univariate and multivariate analyses, there were no factors have significant association with the diagnostic sensitivity of LBC. LBC obtained via percutaneous US-FNA provides good diagnostic value for pancreatic lesions and there was no significant difference between the diagnostic accuracy of LBC and LBC + SC when ROSE was unavailable.

Pancreaticobiliary Cytology Practice in 2021: Results of a College of American Pathologists Survey.

The College of American Pathologists (CAP) surveys provide national benchmarks of pathology practice. To investigate pancreaticobiliary cytology practice in domestic and international laboratories in 2021. We analyzed data from the CAP Pancreaticobiliary Cytology Practice Supplemental Questionnaire that was distributed to laboratories participating in the 2021 CAP Nongynecologic Cytopathology Education Program. Ninety-three percent (567 of 612) of respondent laboratories routinely evaluated pancreaticobiliary cytology specimens. Biliary brushing (85%) was the most common pancreaticobiliary cytology specimen evaluated, followed by pancreatic fine-needle aspiration (79%). The most used sampling methods reported by 235 laboratories were 22-gauge needle for fine-needle aspiration (62%) and SharkCore needle for fine-needle biopsy (27%). Cell block was the most used slide preparation method (76%), followed by liquid-based cytology (59%) for pancreatic cystic lesions. Up to 95% (303 of 320) of laboratories performed rapid on-site evaluation (ROSE) on pancreatic solid lesions, while 56% (180 of 320) performed ROSE for cystic lesions. Thirty-six percent (193 of 530) of laboratories used the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology in 2021. Among all institution types, significant differences in specimen volume, specimen type, ROSE practice, and case sign-out were identified. Additionally, significant differences in specimen type, slide preparation, and ROSE practice were found. This is the first survey from the CAP to investigate pancreaticobiliary cytology practice. The findings reveal significant differences among institution types and between domestic and international laboratories. These data provide a baseline for future studies in a variety of practice settings.

Risk Factors and Interpretation of Inconclusive Endoscopic Ultrasound-Guided Fine Needle Aspiration Cytology in the Diagnosis of Solid Pancreatic Lesions.

The inconclusive cytological findings of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) remain a major clinical challenge and often lead to treatment delays. Patients who had undergone EUS-FNA sampling for solid pancreas lesions between 2014 and 2021 were retrospectively enrolled. The "atypical" and "non-diagnostic" categories of the Papanicolaou Society of Cytopathology System were considered inconclusive and the "negative for malignancy" category of malignancy was suspected clinically. We determined the frequency and predictors of inconclusive cytological finding. A total of 473 first EUS-FNA samples were included, of which 108 cases (22.83%) were inconclusive. Significant increases in the odds of inconclusive cytological findings were observed for lesions with a benign final diagnosis (OR 11.20; 95% CI 6.56-19.54, p < 0.001) as well as with the use of 25 G FNA needles (OR 2.12; 95% CI 1.09-4.01, p = 0.023) compared to 22 G needles. Furthermore, the use of a single EUS-FNA technique compared to the combined use of slow-pull and standard suction techniques (OR 1.70; 95% CI 1.06-2.70, p = 0.027) and less than three punctures per procedure led to an elevation in the risk of inconclusive cytology (OR 2.49; 95% CI 1.49-4.14, p < 0.001). Risk reduction in inconclusive cytology findings was observed in lesions between 2-4 cm (OR 0.40; 95% CI 0.23-0.68, p = 0.001) and >4 cm (OR 0.16; 95% CI 0.08-0.31, p < 0.001) compared to lesions ≤2 cm. The more than two punctures per EUS-FNA sampling with larger-diameter needle (19 G or 22 G) using the slow-pull and standard suction techniques in combination may decrease the probability of inconclusive cytological findings.

The World Health Organization classification of pancreaticobiliary cytopathology stratifies risk of malignancy and outcome for endoscopic ultrasound-guided fine-needle aspiration of the pancreas.

The World Health Organization (WHO) has recently published a classification for reporting pancreaticobiliary cytopathology with differences compared to the Papanicolaou Society of Cytopathology (PSC) classification. Retrospective data were collected from pancreatic endoscopic ultrasound-guided fine-needle aspirations from 2014 to 2017 at a pancreatic cancer center. Absolute risk of malignancy (AROM), relative risk (to benign), performance characteristics, and overall survival were calculated for the entire cohort with comparison of cysts and solid lesions. In total, 2562 cases were included: 16% cyst (n=411) and 84% solid (n=2151). The histologic confirmation rate was 43% (n=1101) and the median follow-up (for benign) was 56months. For WHO I-VII, overall AROM (%) was 23, 22, 62, 13, 65, 97, and 100; cyst AROM was 7, 0, 19, 13, 38, 78, and 100; and solid AROM was 50, 29, 70, 15, 100, 99, and 100. For PSC I-VI, overall AROM (%) was 23, 29, 64, 0 (IVa), 60 (IVb), 97, and 100; cyst AROM was 7, 0, 19, 0, 21, 78, and 100; and solid AROM was 50, 35, 73, 0, 92, 99, and 100. The difference in relative risk for a cyst (vs. solid) overall was 0.38 for WHO and 0.26 for PSC. WHO and PSC categories showed stratification for the probability of overall survival. Cystic versus solid lesion type can dramatically affect AROM, particularly for nondiagnostic (I), benign (II), atypical (III), and WHO V categories. WHO IV conveys a similarly low AROM for cystic and solid types. Both classifications stratify the probability of overall survival, including the newly introduced categories WHO IV and WHO V.

A brief review of the WHO reporting system for pancreaticobiliary cytopathology.

The World Health Organization (WHO), the International Academy of Cytology, and the International Agency for Research on Cancer have developed an approach to standardized reporting of pancreaticobiliary cytopathology. The WHO Reporting System for Pancreaticobiliary Cytopathology (WHO System) revises the Papanicolaou Society of Cytopathology (PSC) System for Reporting Pancreaticobiliary Cytology published in 2015 and replaces the 6 PSC categories with 7 categories: "Insufficient/Inadequate/Nondiagnostic"; "Benign/Negative for malignancy"; "Atypical"; "Pancreaticobiliary neoplasm, low risk/grade (PaN-low)"; "Pancreatic neoplasm, high risk/grade (PaN-High)"; "Suspicious for malignancy"; and "Malignant". In the PSC system, there is a single category for "Neoplastic" lesions that includes 2 groups, 1 for benign neoplasms and 1 named "Neoplastic-other", dominated by premalignant intraductal neoplasms primarily intraductal papillary mucinous neoplasms and low-grade malignant neoplasms (pancreatic neuroendocrine tumors (PanNET) and solid pseudopapillary neoplasms (SPN). In the WHO System, benign neoplasms with virtually no risk of malignancy are included in the "Benign" category and low-grade malignancies (PanNET and SPN) are included in the "Malignant" category, as per the 5th edition of the WHO Classification of Digestive System Tumors, while the non-invasive pre-malignant lesions of the ducts are divided by the cytomorphological grade of the epithelium into PaN-low and PaN-high with distinctly different risks of malignancy. Within each category, key diagnostic cytopathologic features and the ancillary studies for diagnostic and prognostic evaluation, as well as the implications of diagnosis for patient care and management, are outlined. Reporting and diagnostic management options recognize the variations in the availability of diagnostic and prognostic ancillary testing modalities in low- and middle-income countries.

Diagnostic features of low- and high-grade mucinous neoplasms in pancreatic cyst FNA cytology.

Pancreatic cyst cytology evaluates for neoplastic mucin and epithelial grade. This study describes cytological features of low- and high-grade mucinous neoplasms (MNs) using gastrointestinal contaminants for comparison. Histologically confirmed pancreatic cystic neoplasms were reviewed by a panel of cytopathologists to identify which, among 26 selected cytologic features, correlate significantly with low- and high-grade MN. A test for greater than or equal to four of eight high-grade features (three-dimensional architecture, high nuclear:cytoplasmic ratio, moderate nuclear membrane abnormalities, loss of nuclear polarity, hyperchromasia, >4:1 nuclear size variation in one cluster, karyorrhexis, and necrosis) was assessed for identifying a high-grade neoplasms. Additional characteristics of the cohort such as cyst fluid carcinoembryonic antigen results, molecular testing, Papanicolaou Society of Cytopathology classification, and select high-risk clinical features are described. Endoscopic ultrasound fine-needle aspirations from 134 MN and 17 serous cystadenomas containing gastrointestinal contaminants were included. The MN consisted of 112 (84%) intraductal papillary MNs (low-grade=69, 62%; high-grade=24, 21%; and invasive=19, 17%) and mucinous cystic neoplasms (low-grade=20, 90%; high-grade=2, 10%). Half had greater than five clusters of epithelium for analysis. Compared with gastrointestinal contaminants, mucin from MN was thick and colloid-like (40% vs. 6%, p < .01), covered >20% of the smear area (32% vs. none, p < .01), and contained histiocytes (46% vs. 18%, p=.04). Greater than or equal to four of eight select high-grade features was present in 36% of high-grade MN with sensitivity 37% and 98% specificity. Colloid-like features, >20% of smear, and histiocytes correlated with MN. Testing for greater than or equal to four high-grade features had low sensitivity and high specificity for high-grade MN.