Contributed by: Steven J. Rockoff, MD and Diana L. Lam, MD - June 1, 2020
A 37-year-old woman presents for evaluation of a right breast mass that was incidentally seen on a CT exam for an unrelated issue.
Diagnostic ultrasound:
Diagnostic mammogram:
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What is your assessment?
A. BI-RADS 0 (Incomplete); Recommend diagnostic MRI B. BI-RADS 1 (Negative); Recommend one year follow-up C. BI-RADS 2 (Benign); Recommend one year follow-up D. BI-RADS 3 (Probably Benign); Recommend six month follow-up E. BI-RADS 4 (Suspicious); Recommend biopsy
C. BI-RADS 2 (Benign); Recommend one year follow-up
Explanation: The large mass in the right breast at 9:00 is a breast hamartoma, also known as a fibroadenolipoma. This benign mass has the characteristic “breast within a breast” appearance on mammogram, which is a well-circumscribed oval mass composed of normal fibroglandular and adipose tissue. These are benign malformations and do not require biopsy.
The yellows arrows in these ultrasound images demarcate the capsule of the hamartoma. The green stars denote the hypoechoic areas of fibroglandular tissue within the hamartoma and the red arrows denote the hyperechoic areas of fat within the hamartoma:
Although not needed to make the diagnosis, the CT on which the breast hamartoma was partially visualized also demonstrates multiple internal fat elements within the mass:
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