What is the next evaluation step for asymmetry identified on a mammogram?

Next Steps for Mammographic Asymmetry Evaluation

For a mammographic asymmetry, the next evaluation step should be diagnostic mammography with additional views (spot compression, magnification) followed by targeted ultrasound of the area of concern. 1

Diagnostic Approach Algorithm

Initial Evaluation

• Diagnostic mammography with additional views (spot compression, magnification) to better characterize the asymmetry 1
• Targeted ultrasound of the area of concern should be performed concurrently with diagnostic mammography 1

Based on BI-RADS Assessment

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

  • Clinical re-examination in 3-6 months 1
  • Follow-up imaging with diagnostic mammogram and/or ultrasound every 6-12 months for 1-2 years to assess stability 1
  • If stable, return to routine screening 1
  • If clinical progression is noted, proceed to tissue biopsy 1

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

  • Tissue biopsy using core needle biopsy (preferred) or needle localization excisional biopsy 1

Importance of Additional Views

• Standard mammographic views may not fully characterize asymmetries 2
• Spot compression views help separate overlapping tissues and can determine if the asymmetry represents a true finding or summation artifact 3
• Magnification views are particularly helpful for evaluating any associated microcalcifications 1

Role of Ultrasound

• Ultrasound can identify potentially benign causes of asymmetry or identify a target for biopsy 2
• The presence of an ultrasound correlate increases the likelihood of malignancy 4
• Even with negative ultrasound findings, a suspicious asymmetry on mammography should still undergo biopsy 2

Clinical Significance of Asymmetries

• Most asymmetries are benign or represent normal variations in breast tissue 5
• Developing asymmetries (new or increased in conspicuity compared to previous mammograms) should be viewed with particular suspicion, as they have a higher likelihood of malignancy (approximately 15%) 4, 2
• Asymmetries without associated masses, microcalcifications, or architectural distortion are less concerning unless associated with a palpable abnormality 5

Additional Imaging Considerations

• Digital breast tomosynthesis (DBT) can improve characterization of asymmetries by reducing tissue overlap 2
• MRI may be considered for problem-solving in select cases when ultrasound shows no correlate and stereotactic biopsy is not feasible 2
• The presence of an MRI correlate significantly increases the likelihood of malignancy 4

Common Pitfalls to Avoid

• Dismissing a developing asymmetry without complete evaluation - these findings have a higher likelihood of malignancy than stable asymmetries 4, 2
• Relying solely on ultrasound findings - lack of an ultrasound correlate does not exclude malignancy 2
• Failing to correlate imaging findings with clinical examination - asymmetries associated with palpable abnormalities warrant more concern 5

Remember that asymmetries represent a spectrum of findings with varying malignancy risk, with developing asymmetries carrying the highest risk and requiring the most thorough evaluation 6.