From the Guidelines
The asymmetry in the lateral right breast seen on craniocaudal (CC) views is most likely a summation artifact of normal fibroglandular breast tissue rather than a true lesion. This finding is common in mammography and typically does not represent a concerning abnormality, as supported by the American College of Radiology's Breast Imaging Reporting and Data System Atlas (BI-RADS Atlas) 1. To confirm this interpretation, additional imaging views such as spot compression or tomosynthesis (3D mammography) may be helpful to separate overlapping tissues. Summation artifacts occur when normal breast structures overlap on a two-dimensional image, creating an apparent density that can mimic a true mass. These artifacts typically disappear or change significantly when imaged from different angles or with additional views.
According to the ACR Appropriateness Criteria for palpable breast masses, a thorough clinical breast examination is necessary in almost all cases to characterize the palpable lesion, and imaging evaluation is crucial to establish concordance between an imaging finding and a clinically detected mass 1. However, in this case, since the finding is likely a summation artifact, it would fall under Category 1 or 2 of the NCCN clinical practice guidelines, indicating a negative or benign finding, respectively 1. If this finding persists on additional imaging or shows concerning features such as irregular margins or increased density, further evaluation with ultrasound may be warranted. Nevertheless, based on the description provided, this likely represents a normal variant that requires no intervention beyond standard screening protocols.
From the Research
Asymmetry in Breast Imaging
- Asymmetry in breast imaging can be a manifestation of various conditions, including breast cancer 2
- The American College of Radiology's Breast Imaging Reporting and Data System (BI-RADS) categorizes breast asymmetries into four types: asymmetry, global asymmetry, focal asymmetry, and developing asymmetry 2
Benign Fibroglandular Breast Tissue
- Benign fibroglandular breast tissue can cause asymmetry in breast imaging, particularly on craniocaudal (CC) views 2
- The presence of fibroglandular tissue is not significantly correlated with breast cancer, according to a study that evaluated the association between breast cancer and fibroglandular tissue using breast MRI 3
Diagnostic Performance of Imaging Modalities
- Magnetic Resonance Imaging (MRI) has been shown to have high sensitivity and specificity in detecting breast cancer, particularly in dense breast tissue 4, 5
- Ultrasound and mammography also have diagnostic value in detecting breast cancer, but their performance may be affected by breast density and tumor type 4, 5
- Combining imaging modalities, such as MRI and ultrasound, can enhance diagnostic performance and provide important clinical value for early breast cancer detection 5
Summation Artifact
- Summation artifact can occur in breast imaging, particularly on CC views, and may be caused by the superimposition of benign fibroglandular breast tissue 2
- The asymmetry lateral right breast on CC views may represent a summation artifact of benign fibroglandular breast tissue, rather than a malignant lesion 2