Case 14 Answer 3

BI-RADS 4, Suspicious. This is a lobulated mass with indistinct margins, solid on ultrasound, and thus is suspicious.

To fit into the Probably Benign category, the mass would have to be round or oval and circumscribed on the mammogram. But the indistinct margins preclude this possibility. If it had been a cyst, it would have been classified as benign.

Ultrasound-guided core biopsy yielded apocrine metaplasia. This is the typical appearance of apocrine metaplasia on ultrasound. At this time, this appearance is not considered diagnostic, though, so a biopsy is still indicated.

Here is another case of Apocrine Metaplasia. As you can see, the appearance is somewhat characteristic, but overlaps with other entities.