Cytomorphological overview of fine-needle aspiration breast utilizing the International Academy of Cytology – Yokohama system of reporting

Background: Benign and malignant lesions of breast are one of the most common causes of palpable masses seen in women. Fine-needle aspiration cytology (FNAC) is the important modality of diagnosis of breast lumps. Previously, there were no uniform criteria for reporting breast FNAC. To overcome this problem, the newly designed system – International Academy of Cytology (IAC) – Yokohama system of reporting was implemented in 2016. The system offers a structured report to the patient. Aims and Objectives: This study aims to categorize breast FNAC according to the IAC – Yokohama system of reporting, to calculate the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of the test, and to analyze the cytomorphological spectrum of various breast lesions. Materials and Methods: A total of 210 patients presenting with breast lump in cytology section were subjected to FNAC using a 22 gauge needle under all aseptic precautions. Detailed clinical history was taken. All cytology and histopathology examination slides (wherever available) were thoroughly studied. FNAC smears were reported using IAC – Yokohama system of reporting. Results: In our study, benign category (C2) was most commonly seen in 73.33% of cases, followed by 10.48% of cases of atypical probably benign (C3), 2.38% of cases were reported as suspicious (C4), and 11.43% of cases were reported as malignant (C5). Cytohistopathological concordance was seen in 38 cases (88.4%) whereas five cases were reported as discordant. Sensitivity and specificity of the test for the diagnosis of malignancy were 81% and 100%, respectively. PPV was 100%. NPV was 90.90%. Diagnostic accuracy of the test was 93.47%. Conclusion: The newer IAC – Yokohama system of reporting of breast FNAC is simple, has clear diagnostic criteria hence boost up the confidence as well has uniformity of reporting by cytopathologist, and increases the understanding and uniformity in assessment by the attending clinician which help in improving the communication between the pathologist and the treating clinician.

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.

Introduction: Fine Needle Aspiration Cytology (FNAC) is a rapid, minimally invasive and cost-effective procedure with a high sensitivity rate of 92-95% and high Positive Predictive Value (PPV) approaching 100% for the diagnosis of breast malignancies. International Academy of Cytology (IAC) Yokohama system for reporting breast FNACs had been established in 2016 to bring consistency and uniformity of breast cytology reporting. Aim: To classify the breast lesions according to the IAC Yokohama system for cytological reporting of breast lesions. Materials and Methods: This was a retrospective six years study carried out in the Department of Pathology, Karpaga Vinayaga Institute of Medical Sciences, Chinnakolambakkam, Tamil Nadu, India. All females breast FNAC cases reported during the year January 2015 to December 2020 were included in the study according to the inclusion criteria. Relevant clinical and pathological data including the FNAC reports were retrieved from the medical records of the department. Corresponding FNAC smears stained with Haematoxylin and Eosin (H&E) and Papanicolaou stains were reviewed and double-checked with the FNAC reports. All those cases were grouped according to the IAC Yokohama System. Statistical analysis was carried out using Statistical Package for the Social Sciences (SPSS) version 23.0. Results: Of the total 381 female breast FNACs, majority (60%) of them belonged to the age group of 21-40 years. The predominant presenting symptom was palpable breast lump (73%) and Upper Outer Quadrant (UOQ) was involved in 65% of cases. Out of 381 cases, 297 (78%) were benign, 52 (13.6%) were malignant and 32 (8.4%) were inadequate for diagnosis. Total 73.8% cases belonged to “C2” category and fibroadenoma was the most prevalent lesion. Pearson Chi-square test showed highly significant association between patient’s age above 40 years and the risk of having a malignant breast lesion (p<0.0001). Conclusion: FNAC is an effective diagnostic modality for preoperative diagnosis of breast lesions thereby facilitating proper treatment at an early stage of the disease. Also adherence to the standardised cytological reporting system like IAC Yokohama system will ensure quality assurance across various institutions, thereby strengthening the healthcare services.

Introduction:The International Academy of Cytology (IAC) has developed a comprehensive and systematic method that defines five categories for reporting breast fine needle aspiration cytology. These categories stratify breast lesions by their risk of malignancy, providing guidance on management for each category. The aim of the study is to analyze the diagnostic utility of the IAC Yokohama system in breast cytology reporting with histopathological correlation.Methods:This was a cross-sectional observational study. The study included 55 patients with clinically suspected breast lumps who underwent Fine Needle Aspiration Cytology for provisional diagnosis, which was later confirmed by corresponding excisional biopsy and histopathology. The collected data following Fine Needle Aspiration Cytology (FNAC) and histopathology were entered into Microsoft Office Excel software 13. Data analysis was performed using SPSS 16. For diagnostic measurement, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated. The probability of significance was set at the 5% level.Results:Among 55 cases of breast lesions on cytopathology as per the International Academy of Cytology Yokohama System, none of the cases were categorized as Insufficient (C1). Twenty-five cases (45.5%) were categorized as C2 (benign), 5 cases (9.1%) were categorized as C3 (atypia, probably benign), 4 cases (7.3%) were categorized as C4 (suspicious for malignancy), and 21 cases (38.3%) were categorized as C5 (malignant). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for cytopathology compared with histopathology were 86.21% (95% CI: 73.76%–98.66%), 100% (95% CI: 100%–100%), 100% (95% CI: 100%–100%), 86.67% (95% CI: 74.29%–99.05%), and 92.7% (95% CI: 85.54%–99.93%), respectively.Conclusion:The IAC Yokohama system for reporting breast fine needle aspiration cytopathology effectively stratifies patients into five categories and has high sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy with regard to the gold standard histopathology.

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.

Breast cytology is a significant component of the "Triple approach" for pre-operative diagnosis of breast lumps, the other two being clinical assessment and radiological imaging. The role of Fine needle aspiration cytology (FNAC) as a first line investigation in diagnosing breast lesions is well documented, however histopathology is the gold standard. Cyto-histopathological correlation is of great relevance and also increases precision.AIMS \& OBJECTIVES:The present study was conducted with the aim to categorize breast lesions according to the latest standardized reporting system proposed by International academy of cytologists (IAC) in 2016. Evaluation of diagnostic accuracy, sensitivity and specificity of FNAC in diagnosing breast lesions and cyto-histopathological correlation was planned. All FNAs of breast lesions over a period of 2 years were included in the study. The cases were grouped into five standardized categories proposed by the International academy of cytology: Category I (Insufficient material), Category II (Benign), Category III (Atypical, probably benign), Category IV (Suspicious, probably in situ or invasive) & Category V (Malignant) respectively. Specificity, sensitivity, diagnostic accuracy, negative and positive predictive value of FNAC were calculated and cyto-histopathological correlation assessed wherever possible. Out of 468 breast lesions reported on FNAC, the category wise distribution was - Category I, II, III, IV & V accounting for 23(4.9%), 342(73.07%), 7(1.5%), 11(2.35%) and 85(18.16%) respectively. Histopathology was performed in 331/468 cases with cyto histological concordance of 98.4% and a type agreement rate of 90.9%. The sensitivity, specificity, positive and negative predictive value and diagnostic accuracy was 98.90%, 99.16%, 97.82%, 99.58% and 99.09% respectively. FNAC is a simple, reliable, cost effective, first line diagnostic procedure for all breast lumps. In collaboration with physical examination and imaging studies (triple approach), FNAC is a highly sensitive diagnostic tool. Adopting a universally acceptable standardized reporting system for breast cytology can enhance the diagnostic accuracy of FNAC.

Recently the International Academy of Cytology (IAC) introduced a new reporting system for breast fine-needle aspiration cytology that classifies cytologic diagnoses into five-categories: (I) insufficient material, (II) benign, (III) atypical, (IV) suspicious of malignancy, and (V) malignant. The current study was undertaken to categorize the breast lesions utilizing the newly proposed IAC Yokohama classification system and evaluate the risk of malignancy (ROM) for respective categories and the diagnostic yield of this technique. All FNAs of breast lesions over 2.5 years were categorized retrospectively using the newly proposed IAC Yokohama reporting system. The ROM was calculated along with sensitivity, specificity, positive and negative predictive value, diagnostic accuracy, false positive, and false-negative rate using the histological diagnosis as the gold standard. The 512 cases were distributed as follows: Category I (insufficient material) 7.4%, Category II (benign) 74%, Category III (atypical) 5.7%, Category IV(suspicious) 1.4%, and Category V (malignant) 11.5%. Histopathological correlation was available in 285 (55.7%) cases. The respective ROM calculated was 33.3%, 0.5%, 13.3%, 83.3%, and 100% for Category I-V. The Sensitivity, Specificity, Positive and Negative Predictive Value, and Diagnostic accuracy were 95%, 99.5%, 98.27%, 98.6, and 98.5% respectively. Despite previous attempts to establish a standardized diagnostic terminology, there has been a lack of a single internationally approved standardized reporting system allowing substantial diagnostic clarity and incorporating distinct diagnostic categories, each linked with a specific ROM and recommended management. This System also provides enhanced communication between pathologists and attending clinicians for the benefit of the patient.

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.

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.

Objectives: To evaluate the diagnostic accuracy of Fine needle aspiration cytology (FNAC) of breast and to ascertain the use of Fine needle aspiration cytology to differentiate the benign and malignant lesion of the breast and its correlation with histopathological examination with regards to their age, sex, locus and circumstances.Study Design: The present study was done ambispectively and it was conducted in the Department of pathology, 600 bedded capacity tertiary care referral hospital located at Mangalore, Karnataka, India from the duration of January 2015 to March 2017 presenting with complaints of breast lesions. The parameters included in the study were age group, location, duration of lesion and associated regional lymphadenopathy. In this study we included 200 patients whose Fine needle aspiration cytology materials was available. Out of these 200 patients, in 54 Patients surgical material was accessible, cyto-histological correlation was done in those patients.Results: Out of 200 cases of Fine needle aspiration cytology of breast lumps, 160 cases were diagnosed as benign breast lesions, 34 cases were diagnosed as malignant breast lesions, 4 cases were reported as unsatisfactory and the remaining two cases were interpreted as suspicious on cytology. In a total these 200 cases, 54 cases histological examination was carried out. Among these 54 cases 30 were diagnosed as benign breast lesion, 22 cases were interpreted as malignant breast lesion, and the remaining 2 cases were reported as unsatisfactory and suspicious of malignancy on cytology but on histological examination of these 54 cases, 32 were confirmed as benign breast lesions and the other 22 cases were confirmed as malignant breast lesions. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy was 90.9%,93.75%,90.9%,93.75% and 92.6% respectively.Conclusion: In conclusion, Fine needle aspiration cytology of breast lesions has limitations in accuracy. But it has its own circumstances such as rapidity, simplicity and noninvasiveness. It should not be used as the sole diagnostic modality in palpable breast lesions due to false negative and false positive diagnosis. Better it should be combined with other clinical and radiological diagnostic modalities such as physical examination, ultrasonography and mammography.

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 .

Introduction. Breast cancer is the most common cancer among women worldwide. In the Philippine National Cancer registry, 1 in every 13 Filipino women is likely to suffer from breast cancer. Fine needle aspiration cytology (FNAC) is a safe, accurate, fast and economical technique practiced worldwide in breast cancer diagnosis. Objective. To assess the value of FNAC as a rapid diagnostic tool in the local setting with the expectation to provide an immediate and highly reliable diagnosis in more than 90% of breast lesions. Methodology. From January 2010 to December 2014, there were 306 out of 1465 breast FNAC documented cases with histopathological correlation. The FNAC smears were retrieved, retrospectively reviewed blindly and reclassified into 5 categories (C1- C5). All FNAC were performed by pathology residents, pathologists and cytopathologist. Smears were fixed in 95% ethyl alcohol and stained with Papanicolaou method. Results. The FNAC findings showed: 13 (4.25%) unsatisfactory (C1); 160 (52.29%) benign (C2); 23 (7.52%) atypical (C3); 9 (2.94%) suspicious (C4) and 101 (33.01%) malignant cases (C5). There were 120 (39.22%) malignant and 186 (60.78%) benign lesions. There were 3.92% (12/306) false negative and 0.65% (2/306) false positive cases. The FNAC had 90% sensitivity, 99% specificity, 98% positive predictive value, 99% negative predictive value and 95% accuracy. The risks of malignancy for each category were: C1=15%; C2=4%; C3=13%; C4=78% and C5=100%. Conclusion. Despite the increasing preference for core needle biopsy among surgeons, FNAC continues to be an acceptable, affordable, quick and valuable tool contributing significantly to early breast cancer diagnosis and treatment, particularly in developing countries like the Philippines. Owing to its high sensitivity and specificity, it can be used as a screening and confirmatory diagnostic tool. Malignant and benign interpretations of breast FNAC give highly accurate prediction of outcomes but must be correlated with clinical and mammographic findings.

Background: Carcinoma of the breast is one of commonest carcinomas found in Indian women and also around the world. Fine Needle Aspiration Cytology (FNAC), a quick, cost effective and patient compliant procedure, can give an adequate diagnosis to rule out at best the difference between a benign and malignant breast lump. The International Academy of Cytology (IAC) has developed a process for Fine-Needle Aspiration Cytology (FNAC) reporting that is thorough and standardized. C1 to C5 are the categories for breast lesions. Methods: A total of 166 breast FNACs were performed over a period of 2.5 years after fulfilling the inclusion and exclusion criteria and the aspirates were stained by Hematoxylin and Eosin stains and the stained slides were studied and diagnosis was made accordingly. The patients were classified using the IAC classification system that relies on their cytomorphological characteristics. Results: Out of 166 cases, 136 were neoplastic, 6 non-neoplastic and 24 cases were inadequate to opine. Of the 136 neoplastic cases, 89 cases (53.61%) were diagnosed as fibroadenoma and 19 cases (11.44%) were diagnosed as duct carcinoma. Conclusion: The fine needle aspiration cytology is a critical diagnostic tool in the management of patients with breast lump. It is an easy, reliable, patient friendly, repeatable and simple diagnostic test. FNAC can have a very high diagnostic accuracy when performed by experts.

Background: Breast lumps pose a significant health concern globally, contributing to both illness and death. The International Academy of Cytology (IAC) Yokohama system has established a uniform method for reporting breast cytology, categorizing it into five groups: inadequate, benign, atypical, suspicious, and malignant. Aims and Objectives: This study primarily aimed to evaluate breast lesions using the IAC Yokohama System and compare the results with those of corresponding histopathological biopsies. Additionally, the study aimed to analyze the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of breast fine-needle aspiration cytology (FNAC) and determine the risk of malignancy associated with each category. Materials and Methods: In this study, 92 cases were analyzed and categorized according to the IAC Yokohama System. Sensitivity, specificity, PPV, NPV, diagnostic accuracy, and risk of malignancy were determined based on histopathological diagnosis, which was considered the reference standard. Results: Among the 92 breast FNACs, the risk of malignancy for the categories insufficient, benign, atypical, suspicious, and malignant were 0%, 0%, 18.75%, 100%, and 100%, respectively. The highest sensitivity (100%) was achieved when considering atypical, suspicious, and malignant cases as positive results. The specificity was highest (100%) when only malignant or both malignant and suspicious cases were considered positive results. The highest diagnostic accuracy (95.65%) was observed when including malignant and suspicious cases as positive results. Conclusion: Implementing the IAC Yokohama System for reporting breast cytopathology through structured reporting will enhance the quality, clarity, and reproducibility of reports among pathologists and clinicians, which would result in enhanced patient care and management.