How are birthmarks formed?

birthmark, is a popular term, there is no exact clinical direction. refers to the abnormal appearance or color of the skin surface. It can be present at birth, or months or even years after birth. From a medical point of view, it is mainly divided into pigmented and vascular types, pigmented and pigmented and pigmented. Pigmentation, such as Ota nevus, coffee spots, pigmented nevus, nevus, Mongolian spots; Pigmentation, such as anemia nevus, non-pigmented nevus and other blood vessels are mainly divided into hemangioma, red spot nevus. The exact cause of these different birthmarks is not very clear, some are more clear, such as hemangioma, is the abnormal proliferation of blood vessels; red stain is the malformation of vascular development.