Do you have this birthmark?

One of my favorite things to do as a dermatologist is to teach patients about their birthmarks, because usually they've never really had a professional talk to them about their birthmark. It's never caused them any problems, not until they're an adult getting a skin cancer screening that they have looking at their and teaching them. So I'm gonna show you a birthmark on one of my patients because maybe you have one too. This spot right here is called a Nevus depigmentosus, also known as an achromic nevus. This is due to a lack of pigment in the skin and can be distinguished from things like vitiligo because you are born with it and it doesn't change size over your lifetime. However, it can become more obvious if you get tan because it doesn't pick up the color the way the surrounding skin does. You'll see me pressing it here to distinguish it from something called a Nevus anemicus, which is pale due to lack of blood flow, where this is pale due to lack of pigment within the lesion itself. In deeper skin tones, it can look like this or like this. And it doesn't have to be completely white or it can just be a bit more pale than the surrounding skin. So now you know Nevus depigmentosus.