Contributed by: Steven J. Rockoff, MD and Diana L. Lam, MD - June 1, 2020
A 71-year-old woman presents for a screening mammogram:
What is the best interpretation of this exam?
A. Mass in the right breast B. Mass in the left breast C. Focal asymmetry in the right breast D. Focal asymmetry in the left breast
Answer: C. Focal asymmetry in the right breast
Explanation: According to the ACR BI-RADS Atlas, a focal asymmetry is a unilateral deposit of fibroglandular tissue that does not meet the definition of a mass. It is seen on two projections (CC and MLO), has concave-outward borders, and is usually interspersed with fat. A focal asymmetry that is new or larger since the previous exam (as was the case for this patient) could also be called a “developing asymmetry”.
Now that we’ve identified the right breast developing asymmetry, what is the next step?
A. Diagnostic mammogram B. Diagnostic ultrasound C. Stereotactic biopsy D. Follow-up mammogram in six months
Answer: A. Diagnostic mammogram
Explanation: The screening exam would be designated BI-RADS 0, Incomplete. A unilateral right diagnostic mammogram is the correct next step in order to determine if this finding is suspicious enough to warrant biopsy.
The right diagnostic mammogram was performed:
The developing asymmetry persists. A targeted ultrasound at the expected position of the mammographic abnormality in the upper outer quadrant is negative. What your assessment and recommendation?
A. BI-RADS 4 (Suspicious); Stereotactic biopsy B. BI-RADS 3 (Probably Benign); Follow-up mammogram in six months C. BI-RADS 4 (Suspicious); Diagnostic MRI D. BI-RADS 4 (Suspicious); Biopsy the approximate area under ultrasound
A. BI-RADS 4 (Suspicious); Stereotactic biopsy
Explanation: A new and persistent suspicious asymmetry, focal asymmetry, or developing asymmetry that has no definite sonographic correlate should be biopsied with stereotactic guidance. In this case, stereotactic biopsy revealed invasive lobular carcinoma.
