Any changes in the breast or nipples need to be checked out. It could be anything or nothing, but I would want to get it looked at as soon as possible. Don't put it off, that is the bottom line, even if it is something, early treatment will get rid of it. I have had surgery on both of my nipples over the years, for duct papillomas. The sooner you do it, the smaller the scar. Sera
Inverted nipple become un-inverted! 
both my nipples are usually tending towards being inverted, but recently my left one has become un-inverted and is sort of shiny!
Linear Mode
