I had a breast ultrasound and the results say "there is a well defined 4 by 3 by 4 mm nodule with posterior acoustic enhancement but with internal echoes" what does that mean? what's next?

Possible biopsy: Hi! i suspect that the next step will be to try to drain the cyst that appears on the ultrasound. If clear fluid drains from the cyst and does not re-accumulate, that may be the end of it! be absolutely certain to follow your doctors recommendations! good luck! dr brown.

Can't tell: Based on that description, it could be anything from a cyst with some internal debris (benign) to a small cancer (less likely at age 28. Options include close observation with ultrasound and needle biopsy/ aspiration. Talk with your referring md about what the radiologist advised, but do not ignore.