Ladies, a question about your ta-tas.

This is more of a question of curiosity, as the only breasts I’ve really examined are my own. I went bikini shopping a few weeks ago and, in the horrible lighting of the Dillard’s dressing room, I could see a little unevenness on the top of my left breast if I leaned my shoulders back. More in the chest area, but it’s technically breast. Upon closure inspection, it was almost like a line that bulged up more than the other areas of the breast. If it were a lump, it would be huge in order for me to see it, and it wasn’t really shaped like you’d expect a lump to be shaped. I’m wondering if it’s a vein or something that I never noticed in my much more forgiving bathroom lights. Now that I noticed it, though, I can see it in any lighting if I position my body correctly. I haven’t felt it, as the mere thought of feeling for any bump/lump/abnormality on my body nearly sends me into panic mode (my own issue, don’t worry about it), but I was wondering if any women here have something like that.