I have had a sebaceous cyst between my breasts for several years. It had always been fairly small, and I was able to squeeze a white material out of it and that would make it smaller, although it would always refill and get bigger again. It is movable beneath the skin, but before it didn't feel particularly hard, and now it does. Also I am not able to squeeze anything out of it anymore, I suspect because of scarring. Because of it's location, and the fact that it is now hard and is getting larger, I am worried. It does not show on mammograms because it is right between both breasts, on the strenum. I showed it to my dr. at my last appt. and he examined it and said not to worry about it unless it gets large or painful, then it can be removed if that happens. He also told me to stop squeezing it, which I have done, but it is enlarging since I stopped emptying it. It there any chance that a sebaceous cyst can become cancerous, and would you recommend removal? It seems to be enlarging rapidly, and is now visible to the naked eye when I look at my chest, whereas before it was so small I could not see it under the skin....