Strange deep red marks in between thighs of young male?

Patient: Strange deep red marks in between thighs of young male?My fiance has had the marks for going on two years. They start off as small thin red lines, and get larger.. some turn purple or blue, when you run your hands over them you can feel the indentations, some are so large it feels as if someone took an ice cream scoop and scooped a chunk of his skin out. It does not itch, sometimes it get irritating if he sweats, so he constantly tries to keep it as clean as possible. He’s had blood test done some came back above average and has been to a skin specialist which was no help. The doctor had never seen anything like it and looked in books and could only say it’s possibly genetics one else in his family has this… They are similar in appearance to stretch marks but even the doctor was confused as all the common reasons for stretch marks were out of the question. He’s had no dramatic weight gain or loss, has not been on any drugs etc.He is a 21 year old Athletic Built Male…not over muscular or anything….One note a nurse mentioned to us once was asking if he has poor circulation and asked if he gets cold feet..his feet are constantly cold… and said this might be part of the issue. Is this possible?Any ideas or have you seen this condition before? The doctors have left us clueless!