The BI-RADS v2025 manual formally incorporates nonmass lesions into the breast ultrasound lexicon, which changes what a sonographic report is expected to describe. These are lesions without a discrete margin or specific shape — the category that has, until now, had no agreed vocabulary and has therefore often been described loosely or not reported at all.
The classification is by distribution: segmental, linear, focal or regional. Each is then characterised by echo pattern, posterior features and associated findings using the v2025 descriptors. The clinical weight behind this is that nonmass lesions span benign, high-risk and malignant diagnoses with an overall malignancy rate high enough that the review's position is that they warrant tissue diagnosis rather than surveillance.
Three technical factors make them easy to miss, and all three are operator-side. Patient positioning changes the appearance because of the gravitational effect on breast tissue; transducer orientation during real-time scanning determines whether a distribution is appreciated at all; and handheld acquisition is operator-dependent in a way that a mass — which announces itself — tolerates and a nonmass lesion does not.
For a department moving to the new lexicon, the transition is a scanning change as much as a reporting one. Multimodality correlation matters here more than for masses: the review sets out the role of mammography, MRI, contrast-enhanced mammography and FDG PET-CT in working these up. In Indian practice, where handheld ultrasound is often the first and sometimes the only breast imaging a woman receives, active recognition of these lesions is the part that has to happen at the machine, because a lesion not seen live is not available for correlation later.
- Use the v2025 distribution terms — segmental, linear, focal or regional — when reporting a nonmass finding on breast ultrasound
- Treat a nonmass lesion as warranting tissue diagnosis rather than short-interval surveillance by default
- Scan in more than one transducer orientation; a distribution can be invisible in one plane
- Account for patient positioning, which alters appearance through the gravitational effect on breast tissue
- Correlate with mammography and, where available, MRI or contrast-enhanced mammography before deciding management
Why it matters
A finding with no agreed name tends not to be reported, and these carry a malignancy rate that makes omission consequential.
Don't overread it
This is a pictorial review introducing a lexicon rather than a study of how often these lesions are malignant in a screened population.
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