Yesterday morning I noticed a long rope like lump on the skin surface in my breast running in a curved shape when I looked at myself in the mirror. I was alarmed and checked later again to find it had dissapeared. It felt like a vein as I am very skinny and have lots of lumpy veins on my arms and hands. This morning I noticed it again and it was very clearly visable again. Is it usual to have a vein that in your breast that comes up and down like this? Double checked just now and again there is no sign of it and my breast feels smooth. PS I am not pregnant.