A comparative study of breast lesions using the IAC Yokohama System for reporting breast cytopathology against histopathological biopsy

The International Academy of Cytology (IAC) Yokohama System has developed a standardized system of reporting breast cytology. The current study aimed to apply the newly proposed YOKOHAMA classification system along with American College of Radiology Breast Imaging Reporting and Data system (ACR-BI-RADS) scoring to breast fine-needle aspiration cytology (FNAC) cases from the department archives and to assess the risk of malignancy (ROM) for each category. All breast FNACs done between January 20017 and June 2023 were reclassified according to the proposed IAC Yokohama reporting system. Histopathological correlation of the IAC Yokohama system and BI-RADS was done wherever available. A three-category approach was followed based on benign versus malignant, and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated using histopathology as the gold standard. A total of 2130 breast FNACs were performed, of which 469 had a histopathological correlation and 892 had a BI-RADS correlation. The ROM for insufficient, benign, atypical, suspicious, and malignant categories were 29.16%, 3.28%, 28.57%, 100%, and 92.18%, respectively. Maximum specificity (96.8%) was observed when only malignant (cat A) and when both suspicious and malignant cases (Cat B) were taken as positive test results. Highest sensitivity (92.7%) was achieved when atypical, suspicious, and malignant cases were taken as positive test results (Cat C) and highest diagnostic accuracy (94.8%) was seen in category B. The sensitivity, specificity, PPV, NPV, and diagnostic accuracy of BI-ADS were 78.67%, 92%, 85.5%, 87.8%, and 87%, respectively. FNAC and imaging are the key modalities for diagnosing breast lesions. The IAC Yokohama system along with ACR-BI-RADS provides a simple yet useful approach for effectively categorizing the different breast lesions, which is useful for patient management and risk stratification.

Introduction: Breast cancer affects 2.1 million women each year and is the most common cancer among females, followed by lung, colorectum, uterus, and cervix. Breast cancer accounted for 6,26,679 (6.6%) deaths in 2018. Breast cancer incidence is on the rise in every part of the globe, including developed countries. Fine Needle Aspiration Cytology (FNAC) shows high sensitivity, specificity, and accuracy in evaluation of breast lesions. FNAC is part of the triple test and is the gold standard for assessment. The new reporting system for breast FNAC, proposed by the International Academy of Cytology (IAC) Yokohama Breast Cytopathology System, has standardised the reporting system to categorise breast lesions and as unmasked the diagnostic dilemma faced by reporting cytopathologist. Aim: The study aimed to categorise the samples according to IAC Yokohama Breast Cytopathology System and assess the Risk of Malignancy (ROM) for each category and increase the diagnostic yield of breast FNAC. Materials and Methods: A retrospective cohort study included 1,467 breast FNAC cases, which were retrieved and reclassified based on the newly proposed IAC Yokohama System into five categories during January 2017-December 2018 in Kidwai Memorial Institute of Oncology (KMIO), Bangalore. Histopathology correlation was done, and the Risk of Malignancy (ROM) was assessed whenever possible. The study results were analysed using Microsoft excel 2007, sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV), and accuracy ratios were calculated using the MedCalc diagnostic test evaluation calculator, keeping histologic diagnosis as the gold standard. Results: Re-categorisation of 1,467 cases was done according to the Yokohama breast cytopathology system as insufficient material, benign, atypical, suspicious for malignancy, and malignant. The histopathology diagnosis was available in 1,069 cases. The respective ROM for each category was, 7.6% for category 1 (Insufficient), 15.26% for category 2 (Benign), 65.38% for category 3 (Atypical), 83.33% for category 4 (Suspicious) and 99.18% for category 5 (Malignant). Considering malignant cases as positive, sensitivity-86.75%, specificity-97.32%, PPV-99.19%, NPV-66.06% and accuracy of 88.96% was deduced. Conclusion: It is recommended to incorporate the IAC Yokohama system to categorise breast cytopathology with uniform terminologies. This will help diagnose breast lesions more consistently and accurately, which in turn helps the clinician manage the disease and predict the ROM and the patient outcome.

Breast cancer is the most prevalent cancer among women worldwide. In developing countries, fine needle aspiration cytology (FNAC) is commonly used for screening to reduce mortality rates. The International Academy of Cytology has established the Yokohama system to enhance diagnostic clarity and communication between pathologists and clinicians. A triple test approach, incorporating clinical evaluation, imaging, and FNAC, can further improve patient care for breast lesions and may enhance the Yokohama System's effectiveness. A prospective study about breast FNAC was done over a period of one year, from October 2022 to September 2023. The study involved patients with breast lesion referred for FNAC in the department of Pathology. The FNAC results were further classified using the Yokohama system for reporting breast cytopathology, 2016. The cytological findings were correlated with available histopathological results. In the study of 104 cases, 60 (57.7%) of whom had available histopathology results, breast lesions were categorized using the Yokohama system as: 7.7% insufficient, 47.1% benign, 26.9% atypical, 2.9% suspicious of malignancy, and 15.4% malignant. The risk of malignancy varied by category: 0% for category 1, 3.2% for category 2, 47% for category 3, and 100% for categories 4 and 5. The maximum sensitivity was 94.7% when considering atypical, suspicious, and malignant cases as positive. The highest specificity was 97.56% for malignant cases alone, while the best diagnostic accuracy was 83.3% when both malignant and suspicious cases were counted as positive. The Yokohama system effectively classified borderline lesions, facilitating early detection and improved management options. By integrating FNAC with standardized reporting, healthcare providers can make informed decisions, enhancing the diagnosis and treatment of breast lesions.

Standardized reporting of breast FNAC using the International Academy of Cytology Yokohama system and its comparison with histopathology: a cross-sectional study

Background: Worldwide breast malignancy is the major cause for mortality among women. Screening and early detection are crucial. Grey zones of uncertainty in cytomorphological differentiation of benign from malignant lesions can be overcome by Yokohama system of classification. Aims and Objectives: The objectives of this study are as follows: (1) To categorize Breast fine needle aspiration cytology (FNAC) samples according to the international academy of cytology (IAC) Yokohama system. (2) To assess the diagnostic accuracy, sensitivity, specificity, and risk of malignancy (ROM) for each category. Materials and Methods: A retrospective study of 144 breast FNAC cases with histopathological diagnosis was done based on Yokohama System from January 2018 to December 2020. ROM in each category was calculated. The study results were analyzed for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) considering histological diagnosis as the gold standard. Results: Recategorization of 144 cases with histopathological diagnosis was done according to Yokohama system as insufficient material, benign, atypical, suspicious for malignancy, and malignant. The respective ROM for each category was, 7.6% for Category-1 (Insufficient), 15.26% for Category-2 (Benign), 65.38% for Category-3 (Atypical), 83.33% for Category-4 (Suspicious), and 99.18% for Category-5 (Malignant). Considering malignant cases as positive, sensitivity – 86.75%, specificity – 97.32%, PPV – 99.19%, NPV – 66.06%, and accuracy of 88.96% were deduced. Conclusion: Incorporation of IAC Yokohama system to categorize breast cytopathology using uniform terminologies provides diagnostic clarity, consistency, and accuracy in reporting, which in turn helps the clinician to predict the ROM and patient outcome.

Background: Worldwide breast malignancy is the major cause for mortality among women. Screening and early detection are crucial. Grey zones of uncertainty in cytomorphological differentiation of benign from malignant lesions can be overcome by Yokohama system of classification. Aims and Objectives: The objectives of this study are as follows: (1) To categorize Breast fine needle aspiration cytology (FNAC) samples according to the international academy of cytology (IAC) Yokohama system. (2) To assess the diagnostic accuracy, sensitivity, specificity, and risk of malignancy (ROM) for each category. Materials and Methods: A retrospective study of 144 breast FNAC cases with histopathological diagnosis was done based on Yokohama System from January 2018 to December 2020. ROM in each category was calculated. The study results were analyzed for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) considering histological diagnosis as the gold standard. Results: Recategorization of 144 cases with histopathological diagnosis was done according to Yokohama system as insufficient material, benign, atypical, suspicious for malignancy, and malignant. The respective ROM for each category was, 7.6% for Category-1 (Insufficient), 15.26% for Category-2 (Benign), 65.38% for Category-3 (Atypical), 83.33% for Category-4 (Suspicious), and 99.18% for Category-5 (Malignant). Considering malignant cases as positive, sensitivity – 86.75%, specificity – 97.32%, PPV – 99.19%, NPV – 66.06%, and accuracy of 88.96% were deduced. Conclusion: Incorporation of IAC Yokohama system to categorize breast cytopathology using uniform terminologies provides diagnostic clarity, consistency, and accuracy in reporting, which in turn helps the clinician to predict the ROM and patient outcome.

Background: The International Academy of Cytology (IAC). Yokohama System has created a standardized method of describing breast cytology by grouping them into five categories: inadequate, benign, atypical, suspicious, and malignant. To validate the likelihood of cancer in the various categories, several investigations have been undertaken at various institutions as a mandate. Aim: The main objective of the research is to identify the accuracy of fine-needle aspiration cytology (FNAC) for breast lumps by the Yokohama system for reporting and its correlation with histopathology. Methodology: The present study was a retrospective research performed over 8 months. Fine-needle aspiration cytology (FANCs) for breast lumps are performed by the Yokohama system. Whenever accessible, histopathological diagnoses were also retrieved. Statistical Analysis Used: Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were estimated using a histological diagnosis as the gold standard concerning each of the five categories. Results: Out of 200 cases, 106 had histopathological concordance. Five categories: insufficient, benign, atypical, suspicious, and malignant of the IAC Yokohama system were 1.00%, 62.50%, 4.50%, 1.50%, and 30.50%, Category 1 (1%), Category 2 (62.5%), Category 3 (4.5%), Category 4 (1.5%), and Category 5 (30.5%). When malignant, suspicious, and unusual cases were taken into account as positive test findings, the highest level of sensitivity (90.60%) was attained. The maximum specificity (100%) was seen when only malignant patients were taken into account as positive test findings, but the highest diagnostic accuracy (96.22%) was shown when the malignant and suspect categories were taken into account as positive test results. Conclusion: FNAC using the Yokohama system for reporting is an accurate diagnostic tool for breast lumps. The system provides a standardized framework for reporting FNAC findings, and studies have reported high sensitivity and specificity rates for diagnosing breast lumps using FNAC. Therefore, FNAC can be used in conjunction with histomorphology to ensure accurate diagnosis and appropriate management of breast lumps.

Introduction: Breast cancer is rapidly emerging as the leading cause of cancer in Indian women. Cytopathology and histopathology services are required to tackle this growing burden. The use of International Academy of Cytology (IAC) Yokohama Reporting System of breast cytology by classifying them into five categories insufficient, benign, atypical, suspicious and malignant. (IAC) Yokohama Reporting System offers structured protocols, are expected to improve breast cytopathology reporting. Objective : The main objectives of our study were to classify breast fine needle aspirates according to the IAC Yokohama system and assess the risk of malignancy, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Methodology: All breast FNAs done in the above period were retrieved and classified into five categories according to the Yokohama system. Histopathological diagnosis was also retrieved wherever available. Results: The new “International Academy of Cytology (IAC) Yokohama system” was used to categorize 205 patients into five categories based on the cytologic diagnosis. That C1: insucient material (7.8%), C2: benign (64.3%), C3: atypical (7.3%), C4: suspicious of malignancy (7.8%), and C5: malignant (12.6%). Risk of malignancy (ROM) was calculated which was 100% in Yokohama category I, IV and V. In category II ROM was 00% and in category III ROM was 55.5%. FNAC correlation with histopathology was significant (P Value=<0.01 & Chi square value 40.7). Conclusion: The IAC Yokohama system is an excellent system for accurately diagnosing breast fine needle aspirate. Keywords: Histopathology, International Academy of Cytology Yokohama System, Fine­ Needle Aspiration Biopsy Cytopathology

Fine Needle Aspiration Biopsy (FNAB) of the breast is a widely used diagnostic tool for detecting breast lesions, offering high sensitivity and positive predictive value. The International Academy of Cytology (IAC) established the Yokohama System in 2016 to standardise reporting of breast FNAB. To categorise FNAB samples according to the IAC Yokohama System, assess the ROM for each category and evaluate the sensitivity, specificity and predictive values for malignancy diagnosis. This prospective observational study involved predominantly younger adults with the majority presenting with a palpable breast mass. FNAB samples were collected, stained and examined microscopically. Categories were assigned according to the Yokohama System, and the results were compared with histopathological examination (HPE). Diagnostic metrics and ROM were calculated using statistical analysis. The study included 428 patients, with malignant cases comprising 49.5% of the samples, benign cases 43.5%, atypical cases 4.2%, suspicious for malignancy cases 1.9% and insufficient material 0.9%. The risk of malignancy (ROM) was 100% for malignant, 87.5% for suspicious for malignancy, 22.2% for atypical, 2.15% for benign and 25% for the insufficient category. Sensitivity, specificity and accuracy varied across groups, with group A, group B and group C showing accuracy at 92.99%, 97.66% and 95.3%, respectively. The IAC Yokohama System effectively categorises breast FNAB samples, provides accurate diagnostic metrics for malignancy and aids clinical decision-making, particularly in resource-limited settings.

Background and Objective: The International Academy of Cytology (IAC) Yokohama system for reporting breast fine-needle aspiration biopsy (FNAB) cytopathology has been proposed to standardize breast FNAB reporting. The aim of this study was to categorize breast FNAB cases performed by palpation without radiological guidance according to the IAC system, establish the risk of malignancy (ROM) for the categories and assess the system’s utility, pitfalls, and implications in low-resource/financial constraint settings. Methods: A retrospective analysis of palpation-guided FNAB of breast lesions performed without radiological guidance between January 2016 and December 2019 was carried out and was correlated with follow-up biopsies wherever available. A total of 1,089 cases were recategorized using the IAC Yokohama system. Histopathology follow-up was available for 400 cases. The data were analysed for ROM, positive predictive value (PPV), and negative predictive value (NPV). Results and Discussion: Out of 1,089 cases, 4.3% (n = 47) cases were categorized as insufficient, 82% (n = 893) as benign, 2.8% (n = 31) as atypical, 2.7% (n = 29) as suspicious of malignancy, and 8.2% (n = 89) as malignant. Some 400 cases had a follow-up biopsy, based on which, the ROM for the categories were 33.3%, 0.4%, 37.5%, 96%, and 100%. The NPV for the benign category was 99.6%. The PPV of the malignant category was 100%, that of combined suspicious of malignancy and malignant categories was 99%, and of combined atypical, suspicious of malignancy, and malignant was 90.6%. Conclusion: The IAC Yokohama system is useful in standardizing the reporting of cytopathology of breast lesions. FNAB with radiological guidance is ideal but in cases of finance/resource constraints, FNAB by palpation alone is satisfactory if the test result is in the benign, suspicious of malignancy, or malignant categories, which constitute 91.5% of the cases in this study. A repeat ultrasound-guided FNAB and/or core needle biopsy should be recommended for cases in the insufficient/inadequate or atypical categories.

BackgroundFine-needle aspiration cytology (FNAC) of the breast is a well-established technique that aids in the preoperative identification and differentiation between nonneoplastic and neoplastic breast lesions. Breast lesions can be efficiently categorized into different cytological groups using the International Academy of Cytology (IAC) Yokohama System. The aim of this study was to classify breast lesions based on the proposed Yokohama system of reporting breast cytology and identify the need for a unified system of reporting breast lesions.Materials and methodsThis retrospective descriptive study was performed in the Department of Pathology, Government Medical College, Datia, M.P. from January 2019 to June 2023. A total of 762 FNAC slides reported during this period were retrieved, re-examined and reclassified according to the IAC Yokohama System. Histopathological diagnoses were also retrieved and correlated with the cytological findings wherever available.ResultsIn the present study, a total of 762 smears of breast fine needle aspirations were included and categorized using the IAC Yokohama System. There were 3.8% cases (29/762) in the C1 category (insufficient), 71.6% cases (545/762) in the C2 category (benign), 6.3% cases (48/762) in the C3 category (atypical), 3.1% cases (24/762) in the C4 category (suspicious for malignancy) and 15.2% (116/762) cases in the C5 category (malignant).ConclusionFNAC is a reliable diagnostic technique for the evaluation and management of breast lesions prior to surgery. Implementing the IAC Yokohama System for reporting breast cytopathology enhances the accuracy of diagnosing breast lesions, reduces missed diagnoses, and offers reliable estimates of risk of malignancy. Adopting the Yokohama system is a crucial first step in boosting the overall effectiveness of breast cytology reporting among clinicians and pathologists, which will ultimately lead to improved communication and patient care.

The International Academy of Cytology (IAC) gathered together a group of cytopathologists expert in breast cytology who, working with clinicians expert in breast diagnostics and management, have developed the IAC Yokohama System for Reporting Breast Fine-Needle Aspiration Biopsy (FNAB) Cytology. The project was initiated with the first cytopathology group meeting in Yokohama at the 2016 International Congress of Cytology. This IAC Yokohama System defines five categories for reporting breast cytology, each with a clear descriptive term for the category, a definition, a risk of malignancy (ROM) and a suggested management algorithm. The key diagnostic cytopathology features of each of the lesions within each category will be presented more fully in a subsequent atlas. The System emphasizes that the crucial requirements for diagnostic breast FNAB cytology are a high standard for the performance of the FNAB and for the making of direct smears, and well-trained experienced cytopathologists to interpret the material. The performance indicators of breast FNAB, including specificity and sensitivity, negative predictive value, positive predictive value and ROM stated in this article have been derived from the recent literature. The current practice of breast FNAB has evolved with the increasing use of ultrasound guidance and rapid on-site evaluation. Two recent publications have shown a range of ROM for the insufficient/inadequate category of 2.6–4.8%, benign 1.4–2.3%, atypical 13–15.7%, suspicious of malignancy 84.6–97.1%, and malignant 99.0–100%. The management algorithm in the System provides options because there are variations in the management of breast lesions using FNAB and core-needle biopsy in those countries utilizing the “triple test” of clinical, imaging, and FNAB assessment, and also variations in the availability of CNB and imaging in low- and middle-income countries. The System will stimulate further discussion and research, particularly in the cytological diagnostic features of specific lesions within each category and in management recommendations. This will lead to continuing improvements in the care of patients with breast lesions and possible modifications to the IAC Yokohama System.

The International Academy of Cytology (IAC) gathered together a group of cytopathologists expert in breast cytology who, working with clinicians expert in breast diagnostics and management, have developed the IAC Yokohama System for Reporting Breast Fine-Needle Aspiration Biopsy (FNAB) Cytology. The project was initiated with the first cytopathology group meeting in Yokohama at the 2016 International Congress of Cytology. This IAC Yokohama System defines five categories for reporting breast cytology, each with a clear descriptive term for the category, a definition, a risk of malignancy (ROM) and a suggested management algorithm. The key diagnostic cytopathology features of each of the lesions within each category will be presented more fully in a subsequent atlas. The System emphasizes that the crucial requirements for diagnostic breast FNAB cytology are a high standard for the performance of the FNAB and for the making of direct smears, and well-trained experienced cytopathologists to interpret the material. The performance indicators of breast FNAB, including specificity and sensitivity, negative predictive value, positive predictive value and ROM stated in this article have been derived from the recent literature. The current practice of breast FNAB has evolved with the increasing use of ultrasound guidance and rapid on-site evaluation. Two recent publications have shown a range of ROM for the insufficient/inadequate category of 2.6–4.8%, benign 1.4–2.3%, atypical 13–15.7%, suspicious of malignancy 84.6–97.1%, and malignant 99.0–100%. The management algorithm in the System provides options because there are variations in the management of breast lesions using FNAB and core-needle biopsy in those countries utilizing the “triple test” of clinical, imaging, and FNAB assessment, and also variations in the availability of CNB and imaging in low- and middle-income countries. The System will stimulate further discussion and research, particularly in the cytological diagnostic features of specific lesions within each category and in management recommendations. This will lead to continuing improvements in the care of patients with breast lesions and possible modifications to the IAC Yokohama System.

BackgroundThe International Academy of Cytology (I.A.C.) Yokohama System to report breast cytopathology can effectively categorize breast diseases into different cytological groups. Fine needle aspiration (FNAC) from the lesions in the breast has been regarded as a major method of diagnosing breast cancer, particularly in rural settings. The major purpose of this study was to validate the diagnostic accuracy of breast FNA utilizing the IAC Yokohama system in future endurances. Histopathological examination is considered the gold standard for diagnosing benign as well as malignant breast lesions and is compared with FNA results.Material and methodsResearch on patients getting a core-needle, incisional, or excisional biopsy of breast lesions between January 1st, 2021, and December 31st, 2021, was conducted at a tertiary care center in central India. 216 breast FNAs were recorded utilizing the IAC Yokohama system, and the most appropriate category was assigned for every case and correlated with histopathology to evaluate the effectiveness of IAC system.ResultsThe new "International Academy of Cytology (IAC) Yokohama system" was used to categorize 216 patients into five categories based on the cytologic diagnosis.Those were C1: insufficient material (8.7%), C2: benign (65.7%), C3: atypical (1.8%), C4: suspicious of malignancy (2.7%), and C5: malignant (20.8%). FNACs were associated with ancillary testing and histological diagnosis to examine diagnostic accuracy. The overall Specificity, sensitivity, negative predictive value, positive predictive value, and accuracy were calculated with the risk of malignancy.ConclusionWith high specificity and sensitivity for each type of situation, for all tumors, and for each analyzed BI-RADS category, the IAC Yokohama system provides excellent accuracy for breast FNA .

Fine-needle aspiration cytology (FNAC) remains widely used for the evaluation of palpable breast lesions, particularly in resource-limited settings, though histopathology is the gold standard. The International Academy of Cytology (IAC) Yokohama System provides a standardized five-tier reporting framework with defined risk of malignancy (ROM). This study aimed to evaluate its diagnostic performance, reproducibility, and applicability in a tertiary care setting. A total of 548 breast FNACs from 533 patients were reclassified both prospectively and retrospectively according to the IAC Yokohama categories. Histological correlation was available in 228 cases. Interobserver agreement was assessed among two senior cytopathologists and one junior pathologist using unweighted and weighted kappa statistics. Diagnostic performance was calculated against histology using three definitions of test positivity (Cat-5 only; Cat-4 & 5; Cat-3-5). A total of 548 FNACs from 533 patients were reclassified using the IAC Yokohama system: Cat-1 (36, 6.6%), Cat-2 (318, 58.0%), Cat-3 (14, 2.6%), Cat-4 (25, 4.6%), and Cat-5 (155, 28.3%). Histological correlation was available in 228 cases. The observed ROM was 50% for Cat-1, 7.9% for Cat-2, 45.5% for Cat-3, 93.8% for Cat-4, and 100% for Cat-5. Diagnostic accuracy improved with reclassification: in Group A (Cat-5 positive), sensitivity increased to 78.4% and specificity was 100%; in Group B (Cat-4 & 5 positive), sensitivity was 90.9% and specificity was 97.9%; and in Group C (Cat-3-5 positive), sensitivity reached 94.7% with a specificity of 89.6%. ROC analysis confirmed superior discrimination for the Yokohama system (AUC 0.94 vs. 0.88 for the original). Interobserver reproducibility was excellent, with weighted kappa values of 0.954 (P1 vs. P2), 0.942 (consensus vs. P3), and 0.939 (P2 vs. P3). Agreement was highest in benign and malignant categories and lowest in atypical and suspicious groups. The IAC Yokohama System showed high diagnostic accuracy, excellent reproducibility, and reliable risk stratification. By reducing false negatives and minimizing equivocal reporting, it improved alignment with histology compared with the conventional descriptive system, supporting its routine use in breast cytology practice.