What is the management plan for breast asymmetry detected on a mammogram?

Management of Breast Asymmetry on Mammogram

Breast asymmetry detected on mammogram requires a systematic diagnostic evaluation with additional imaging to determine if it represents normal variation or potential malignancy.

Initial Evaluation

When breast asymmetry is identified on a screening mammogram, the following diagnostic approach is recommended:

1. Diagnostic mammogram with additional views:

   • Spot compression views to determine if the asymmetry represents true tissue abnormality or summation artifact 1
   • Mediolateral (ML) views to provide additional perspectives 1
   • Magnification views if suspicious microcalcifications are present 1

2. Ultrasound evaluation:

   • Should be performed if the asymmetry persists on diagnostic mammographic views 1
   • Helps differentiate solid masses from cystic lesions 1
   • Can identify lesions not visible on mammography 1
   • Particularly useful for evaluating asymmetries that could represent underlying masses 1

Classification and Management Based on BI-RADS Assessment

BI-RADS Category 1-3 (Negative, Benign, or Probably Benign)

• Re-examination in 3-6 months with imaging as needed 2
• Age-appropriate diagnostic mammogram and/or ultrasound every 6-12 months for 1-2 years to assess stability 2
• If findings remain stable, resume routine screening 2
• If clinical suspicion increases during follow-up, tissue biopsy is recommended 2

BI-RADS Category 4-5 (Suspicious or Highly Suggestive of Malignancy)

• Tissue biopsy is necessary using core needle biopsy (preferred) or needle localization excisional biopsy with specimen radiograph 2
• When needle biopsy is performed, concordance between the pathology report and imaging finding must be obtained 2
• If pathology and imaging are discordant, breast imaging should be repeated and additional tissue sampled or excised 2

Special Considerations

Developing Asymmetry

• Defined as a focal asymmetric deposit that has appeared or increased in size or conspicuity since a previous examination 3
• Represents a higher risk for malignancy with a positive predictive value of 12.8% in screening and 26.7% in diagnostic settings 3
• Even with normal ultrasound findings, biopsy is generally warranted as 23.8% of cancers presenting as developing asymmetries may have no correlate on ultrasound 3

Digital Breast Tomosynthesis (DBT)

• Can aid in evaluation by improving sensitivity and specificity 4
• Helps with localization of the lesion in three-dimensional space 4
• May be used as an adjunct to standard mammographic views 2

Diagnostic Challenges

• Most asymmetries are benign or caused by summation artifacts 5
• A study of 8,408 mammograms found that 3% demonstrated asymmetric breast tissue, with malignancy only found in patients who had a palpable abnormality associated with the asymmetric tissue 6
• Pseudoangiomatous stromal hyperplasia is a common histopathologic finding in developing asymmetric breast tissue 7

Follow-up Recommendations

• Women with benign results exhibiting pathology/image concordance should be followed up with mammography every 6-12 months for 1-2 years before returning to routine screening 2
• Those with atypical hyperplasia, LCIS, or other potentially pathologic conditions should undergo surgical excision and appropriate follow-up 2

Key Pitfalls to Avoid

1. Dismissing asymmetry without complete evaluation: Even subtle asymmetries warrant thorough assessment as they may represent early malignancy.

2. Relying solely on ultrasound: Normal ultrasound findings do not exclude malignancy in cases of developing asymmetry 3.

3. Inadequate follow-up: Asymmetries that appear benign still require appropriate surveillance to ensure stability over time.

4. Missing correlation between clinical and imaging findings: Palpable abnormalities associated with asymmetric tissue should raise higher suspicion for malignancy 6.