Non-mass finding (breast ultrasound)
A non-mass finding on breast ultrasound refers to a discrete region of altered breast parenchymal echotexture that does make a mass shape (i.e. non-identifiable in two planes). "Non-mass finding" is not a current BI-RADS descriptor.
Terminology
Non-mass findings are described in numerous ways in the literature
- non-mass lesion
- non-mass-like lesion
- non-mass image-forming lesion
- vague area of altered echotexture
- duct-like structures
- focal shadowing
Epidemiology
Non-mass findings have been reported to occur in ~5% of diagnostic or screening breast ultrasound .
Pathology
The malignancy rate for non-mass findings on breast ultrasound is unknown. Wide variations in benign rate (46-90%) and malignancy rate (10-54%) have been reported .
A wide range of benign and malignant conditions have been reported to represent non-mass findings including :
- benign: fibrocystic change, stromal fibrosis
- malignant: high-grade DCIS, breast cancer (ductal, lobular)
Radiographic features
Ultrasound
Non-mass findings are focal, linear-segmental or regional areas of altered breast echotexture that do not make a mass shape :
- hypoechoic, hyperechoic or mixed
- non-identified in two planes
- lack of conspicuous or biconvex margins
- lack of conspicuous shape
Associated features :
- calcifications (most commonly associated with malignancy)
- acoustic shadowing
- architectural distortion
- tubal or ductal architecture
Mammography
The presence of ultrasound non-mass finding correlates of a mammographic finding (most commonly calcifications, asymmetric density, architectural distortion) are more associated with a malignant than benign pathology .
