that is kind of weird isn't it? unfortunately only a physical examination can help figure out what those marks are. from your description they almost sound like stretch marks but the shin would be a very odd place to find stretch marks. i'd suggest you make an appointment with your primary care provider to get them looked at. i don't think they're the hallmark of anything serious but i'm not a doctor. a physician nurse practitioner or physician assistant might see these marks as a sign of some other condition. that's why i'm suggesting you see a doctor. this isn't an emergency situation but it's worth getting checked out. i realize this answer is unsatisfying but i hope you find it helpful!
what are these strange lines on my left shin? started appearing about 9 months ago and are not scars or pressure marks. there are 8 indented lines on my left shin that started appearing about 9 months ago. sometimes they are not visible but when they are they are always exactly the same. i have never injured my leg so they are not scars and they are definitely not pressure marks from socks or pants. they are about 1 inch long and run perfectly parallel with each other.