finding firoglandular densitities, well marginated

mammogram has found 2 densities, one 10 mm and the other breast 4mm, not there a year ago.  Going back for more with possible ultresound.  How different are the densities on the mammogram from actual malign nodules?  How scary are these?  thanks

[Cleveland Clinic]

Dear pearlsophie:  You should discuss these densities with your doctor.  Usually, the radiologist will grade any density according to how suspicious it appears on mammogram.  Then the radiologist would make further recommendations regarding what steps to take next...additional imaging, biopsy, etc.