Non-mass finding (breast ultrasound)

Last revised by Andrew Murphy on 23 Mar 2023

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. 

Non-mass findings are described in numerous ways in the literature 1-3:

  • non-mass lesion
  • non-mass-like lesion
  • non-mass image-forming lesion
  • vague area of altered echotexture
  • duct-like structures
  • focal shadowing

Non-mass findings have been reported to occur in ~5% of diagnostic or screening breast ultrasound 4.

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 1.

A wide range of benign and malignant conditions have been reported to represent non-mass findings including 1,2,4:

Non-mass findings are focal, linear-segmental or regional areas of altered breast echotexture that do not make a mass shape 1,2,4:

  • hypoechoic, hyperechoic or mixed
  • non-identified in two planes
  • lack of conspicuous or biconvex margins
  • lack of conspicuous shape

Associated features 1,3:

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 1

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