The Impact of International Academy of Cytology Yokohama System in Breast Fine-Needle Aspiration Biopsy Cytology and its Correlation With BI-RADS: A 6-Year Single-Institutional Experience

Background: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.