Hypoechoic area on breast ultrasound came back as benign breast tissue with lactational changes. can a mass come back as this? i'm worried.i'm nursing

Yes: Beast feeding women can have exaxctly that pathology. I'm a little surprised you even had a biopsy given your age and the ultrasound finding with you breast feeding.

Depends: Yes it could. It depends on the size the radiologist measured it as and if that correlates with what the pathologist saw under the microscope.

Breast mass: It will be important to follow up with your physician to ensure that the images and the pathology report are concordant (that they agree) and, probably, get a follow-up ultrasound to ensure stability or resolution of the mass.