Your question is a good one, as this is something that I think a lot of people might not even think about. First let me clarify a couple of small, but important, details. When we speak of the "nipple," many people include what we surgeons typically call the "nipple/areolar complex," that is, the part of the breast that is pigmented and includes both the circular areola surrounding the projecting nipple, and the nipple itself, which is most accurately just the part of the breast that projects outward and contains the milk ducts and their openings. That being said, it is safe to inject autologous fat into either or both of these parts of the breast. We usually have different goals in mind when considering injection of fat into these two different specific structures. Often times these parts become "deflated" and/or stretched after childbirth or breastfeeding, and fat injection may be more appropriate than surgical modification in those cases in which improvement is desired. Fat transfer not only can change the size, shape, or fullness of these structures, but the actual tone and texture of the tissue often improves because of the regenerative effects of fat transfer on a cellular and tissue level. One caveat here is that, at least in my experience, it is technically easier and probably more reliable to consider injecting very small aliquots of micronized fat, such as micro- or nanofat into these structures, as opposed to the larger particle sizes of fat typically thought of when discussing fat transfer into the breast or buttocks. This is still fat transfer, just on a smaller scale, as the fat is "broken down" through specific processing steps to smaller and smaller sized particles, allowing it to be injected even through a 30 gauge ( tiny "Botox-sized") needle. Thus, the typically denser, more fibrous tissues of the nipples, where there are more milk ducts and fibrous support structures, will be more easily injected this way as opposed to trying futitely to get the larger fat particles in using larger bore blunt cannulas. Not every patient will be an appropriate candidate for this, however, so if you are going to consider getting this done, it would be best for you to idenitify a board certified surgeon who has a lot of experience in not only breast surgery, but also injecting micronized fat, as this will ensure that you are getting the best information and most appropriate recommendations for the best outcomes in your specific case. Best of luck.
