Conclusions

The present study validates the clinical utility and diagnostic accuracy of the IAC Yokohama System for reporting breast FNAC. The system provides a structured, standardized, and reproducible approach for categorizing breast lesions with an associated risk of malignancy. The progressive increase in the risk of malignancy from Category I to Category V observed in this study confirms the reliability and predictive value of the Yokohama classification. The high specificity and NPV further highlight the usefulness of FNAC as a reliable method for ruling out malignancy and reducing unnecessary surgical interventions in benign breast lesions.

The findings also emphasize the importance of careful evaluation and follow-up of atypical and suspicious categories, along with clinicoradiological correlation and histopathological confirmation, particularly in discordant cases.

Future large-scale, multicentric, and prospective studies incorporating detailed clinicoradiological correlation are required to strengthen the validation of this system. The integration of ancillary techniques, such as immunocytochemistry and molecular markers, may further improve diagnostic accuracy, particularly in indeterminate categories.

FNAC remains a rapid, minimally invasive, cost-effective, and accurate diagnostic modality, especially in resource-limited settings.