What is the next step in evaluating an asymmetry in the right breast seen on a craniocaudal (CC) view?

Evaluation of Mammographic Asymmetry on CC View

The next step is diagnostic mammography with spot compression views of the asymmetry, followed by targeted ultrasound of the area of concern. 1

Algorithmic Approach to Workup

Step 1: Diagnostic Mammography with Additional Views

• Perform spot compression views to determine if the asymmetry represents true tissue or summation artifact from overlapping normal fibroglandular tissue 1, 2
• Consider magnification views if any associated microcalcifications are present 1
• Additional lateral or rolled views help localize the finding in three-dimensional space 2
• Digital breast tomosynthesis (DBT) can improve sensitivity and specificity in characterizing asymmetries, though it is not mandatory 2

Step 2: Targeted Ultrasound

• Perform targeted ultrasound of the area of concern concurrently with diagnostic mammography 1
• Ultrasound can identify a solid mass, complicated cyst, or echogenic tissue corresponding to the asymmetry 3
• The absence of a sonographic correlate does NOT exclude malignancy and should not preclude biopsy if the mammographic finding remains suspicious 2, 3

Critical Decision Points Based on BI-RADS Assessment

If 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
• Return to routine screening if stable 1

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

• Tissue biopsy is mandatory using core needle biopsy (preferred) or needle localization excisional biopsy 1
• Biopsy should proceed even without an ultrasound correlate if mammographic suspicion persists 2, 3

Important Clinical Context

Malignancy Risk

• Asymmetries account for approximately 3% of screening mammograms 4
• While most asymmetries are benign or summation artifacts, a developing asymmetry (new or increased conspicuity) is an uncommon but important manifestation of breast cancer 2
• In one study, 19.4% of focal asymmetric densities that underwent biopsy were malignant 3

Common Pitfalls to Avoid

• Do not dismiss an asymmetry simply because ultrasound is negative—the negative predictive value of ultrasound for breast cancer in focal asymmetric density is 89.4%, meaning 10.6% of cancers will have no sonographic correlate 3
• Asymmetries associated with palpable findings warrant heightened suspicion, as all three malignancies in one series had associated palpable abnormalities 4
• Stable asymmetric breast tissue without mass, calcifications, or architectural distortion is generally benign unless associated with palpable findings 4

When to Consider MRI

• Diagnostic breast MRI can be used for problem-solving or biopsy planning if no ultrasound correlate is identified and stereotactic biopsy is not feasible 2
• This represents a minority of cases and is not part of routine initial workup 2

Summary of Recommended Pathway

The asymmetry described in the right breast at mid-depth on CC view slice 32 requires immediate diagnostic workup with spot compression mammography and targeted ultrasound 1. The finding should be fully characterized mammographically first, then correlated with ultrasound 2. Based on the final BI-RADS category, management will range from short-interval follow-up (BI-RADS 3) to tissue biopsy (BI-RADS 4-5) 1. The long-term stability of bilateral diffuse calcifications mentioned in the left breast represents benign findings and requires no additional workup 5.