Non-mass Lesions and Practical Breast Ultrasound Reporting in the Breast Imaging Reporting and Data System Version 2025 Era: A Narrative Review

Abstract

Breast ultrasound is central to diagnostic breast imaging because it is widely available, dynamic, non-ionising, and well suited to evaluating palpable abnormalities, dense breasts, mammographic correlates, and axillary nodes. The Breast Imaging Reporting and Data System (BI-RADS) version 2025 provides an opportunity to refine breast ultrasound reporting beyond the traditional mass-centred approach. This narrative review summarises practical reporting implications of the BI-RADS v2025 era for breast ultrasound, with emphasis on the glandular tissue component, clarification of cystic and mixed solid-cystic lesions, non-mass lesions, elastography, and axillary lymph node assessment. Non-mass lesions should be described only when the abnormality is reproducible, visible in at least two planes, and clinically relevant; key descriptors include distribution, echogenicity, associated ductal change, echogenic foci or calcifications, vascularity, posterior features, and elasticity when available. Distinguishing simple and complicated cysts from mixed solid and cystic masses can reduce inconsistent categorisation and avoid unnecessary biopsy. Elastography should be treated as an adjunct to B-mode ultrasound and clinical context rather than an independent determinant of final assessment. Axillary ultrasound should prioritise morphology, including cortical thickness, focal or eccentric cortical abnormality, hilum status, shape, margins, and vascularity, rather than size alone. The distinctive contribution of this review is an implementation-oriented framework that links descriptors to scenario-based BI-RADS assessment directions, structured report elements, and management wording suitable for diverse practice environments, including resource-limited settings.