Dark skin patches

Hi everyone, I am due to go to a breast clinic tomorrow for an ultrasound and biopsy on a lump I found 5 weeks ago (on the first day of a three week holiday!!) I noticed I had a pink patch of skin covering the area where the lump is, but also I noticed last night that I have two very faint dark skin patches on my breast which the lump is in. They feel different to the rest of the skin in that they are smoother, almost like a pebble feel and quite numb. Anyone else have this? They are really difficult to see - I had to stand directly in the light to see them. xx