Hi, my skin behind the knees are comparatively dark. I didn't have them as a child but I have been having the problems for about a couple of years. I'm a 14 years old girl. At first, we thought it's just some dirt because I don't regularly bath due to water problems and busy schedule, but as I started getting conscious about it, I realized they wouldn't go away even if I shower regularly. They tend to spread if I'm not regularly showering. There's no form of pain, itch or any kind of blisters. The skin is soft. I'm a student and there is always sun exposure but I don't really apply sunscreens. But the sun wouldn't just affect that area, will it? Can you please suggest me?