The continuing role of breast fine-needle aspiration biopsy after the introduction of the IAC Yokohama System For Reporting Breast Fine Needle Aspiration Biopsy Cytopathology

Background: Ultrasound-guided fine-needle aspiration biopsy (FNAB) (US-guided FNAB) is a rapid and cost-effective procedure for the diagnosis of breast lesions. Our Institution has a long tradition in breast FNAB performed by cytopathologists; recently we adopted both US guidance and a five-tiered classification system similar to that proposed by the International Academy of Cytology (IAC). The aim of this study was to demonstrate the continuing role of US-guided FNAB in the diagnosis of breast lesions, despite the growing adoption of core-needle biopsy (CNB). Methods: The laboratory information database system was searched to obtain the breast FNAB diagnostic reports recorded from 2010 to 2017 and classified using a five-tiered Classification System; each entry was matched with the available histology. Results: A total of 4624 breast FNAB samples were retrieved. Of these, 1745/4624 cases (37.7%) had histological follow-ups. The risk of malignancy (ROM) was 4.9% for benign, 20.7% for atypical, 78.7% for suspicious of malignancy, and 98.8% for malignant. When the atypical category was evaluated as a negative index, the positive predictive value was 93.73%, and the negative predictive value was 90.78%, reaching an overall diagnostic accuracy of 92.82%. Conclusions: The IAC Yokohama System for Reporting Breast FNAB Cytopathology clearly identifies different diagnostic categories with increasing ROM. Most of the FNAB samples were classified as benign or malignant (65.3%), warranting prompt management for these patients. Moreover, the inclusion of the atypical category as a low-risk indeterminate category avoided overtreatment of benign lesions. Thus, despite the well-established merits of CNB, US-guided FNAB still represents a cost-effective and rapid nonoperative diagnostic approach.