Evaluation of the IAC Yokohama System for Reporting Breast Fine Needle Aspiration Biopsy: An Institutional Study (Code-T0056)

Introduction: Fine Needle Aspiration Biopsy (FNAB) is a widely used, minimally invasive diagnostic technique for evaluating breast lesions, recognized for its high sensitivity and predictive value. In 2016, the International Academy of Cytology (IAC) introduced the Yokohama System to standardize FNAB reporting, enhancing diagnostic accuracy and consistency. This study evaluates the application of the Yokohama System in categorizing breast lesions, assessing the risk of malignancy (ROM) for each category, and determining diagnostic performance metrics.

Aims and Objectives:

Primary Objective

Assess the applicability and reliability of the Yokohama System for reporting breast fine needle aspiration biopsy.

Secondary Objective

1. To categorize FNAB breast according to IAC Yokohama system for reporting breast fine needle aspiration biopsy.
2. To access the Risk of malignancy (ROM) for each category.
3. To access the sensitivity, specificity and predictive values (PV) for diagnosis of malignancy.

Methods: This prospective observational study was conducted from June 2021 to May 2023, including 300 female patients with breast masses undergoing FNAB. Samples were collected under ultrasound guidance, processed, and categorized based on the Yokohama System. Histopathological examination (HPE) findings served as the gold standard for comparison. Diagnostic metrics and ROM were analyzed statistically.

Results: The study included 300 patients, predominantly aged 35–50 years. Malignant cases accounted for 47%, benign cases 45.5%, atypical cases 4.5%, suspicious for malignancy 2.5%, and insufficient material 0.5%. ROM was 0% for insufficient material, 3.5% for benign, 48% for atypical, and 80% for suspicious categories. The Yokohama System demonstrated an overall sensitivity of 89%, specificity of 92%, and diagnostic accuracy of 91%.

Conclusion: The IAC Yokohama System provides a reliable framework for FNAB reporting, delivering high diagnostic accuracy and aiding clinical decision-making. Its standardized approach is particularly valuable in resource-limited settings, ensuring consistent and effective management of breast lesions.

Keywords: Fine Needle Aspiration Biopsy, FNAB, Yokohama System, breast lesions, malignancy diagnosis, risk of malignancy.