The role of the IAC Yokohama System for Reporting Breast Fine Needle Aspiration Biopsy and the ACR Breast Imaging‐Reporting and Data System in the evaluation of breast lesions

Background Stratification of breast lesions for appropriate management is achieved through an integration of clinical examination, imaging, and fine needle aspiration biopsy (FNAB). The current study aimed to evaluate the combined effectiveness of the widely used Breast Imaging‐Reporting and Data System (BI‐RADS) with the recently proposed International Academy of Cytology (IAC) Yokohama System for Reporting Breast Fine Needle Aspiration Biopsy Cytopathology. Methods A retrospective analysis was done on all breast FNABs from 2016 through 2020. The cases were categorised according to the IAC Yokohama System. Histopathological correlation of the BI‐RADS and IAC Yokohama System was performed. The rate of malignancy (ROM) for each category of the BI‐RADS and IAC Yokohama System was calculated. Results The ROM values for categories I to V were 38%, 0.6%, 21.9%, 100%, and 97%, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of FNAB with category III assumed as malignant were 98.9%, 85%, 76.1%, 99.3%, and 89.5%, respectively. With category III assumed as benign, these indices were 90.8%, 98.9%, 97.5%, 95.7%, and 96.2%, respectively. The sensitivity, specificity, PPV, NPV and accuracy of BI‐RADS were 91.5%, 81.9%, 72%, 95%, and 85.1%, respectively. Conclusions FNAB is still an indispensable test in the evaluation of breast lesions. The utilisation of the IAC Yokohama reporting system for breast cytology in conjunction with ACR BI‐RADS aids in better stratification of lesions. The specificity and positive predictive value of FNAB are high when IAC Yokohama category III (atypical) is considered negative for malignancy. The utilisation of BI‐RADS in cases where the cytological diagnosis is inconclusive (Categories I, III) will help the clinician decide on appropriate management.