Contralateral Malignancy on Breast MRI

IMAGING FINDINGS: ​
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Post-contrast breast MRI image performed to assess extent of disease demonstrate the known biopsy proven malignancy (index lesion) in the left breast. There is a rim enhancing mass containing a biopsy clip in the inferior left breast at a posterior depth.  The second post-contrast image demonstrates an irregular, enhancing mass in the central right breast at a middle depth. This is highly suspicious for contralateral disease.
 
WHY IT MATTERS:

1. Studies have shown that MRI can detect otherwise occult contralateral breast cancers in an average of 5% of women with a recent diagnosis of breast cancer.
2. Breast MRI for extent of disease is important. When contralateral cancer is diagnosed after the initial treatment, the woman must undergo a second round of cancer therapy rather than the single round that would have been administered if the contralateral cancer had been detected at the time of the initial diagnosis.

FURTHER READING:
MRI Evaluation of the Contralateral Breast in Women with Recently Diagnosed Breast Cancer (N Engl J Med, 2007)