birthmarks

The two main types of birthmarks are differentiated by their causes. Vascular (blood vessel) birthmarks happen when blood vessels don't form correctly — either there are too many of them or they're wider than usual. Pigmented birthmarks are caused by an overgrowth of the cells that create pigment in skin. The most common vascular birthmarks are macular stains, hemangiomas, and port-wine stains: Macular stains. Hemangiomas are classified as superficial when they appear on the surface of the skin ("strawberry marks") and deep when found deeper below the skin's surface. Deep hemangiomas may be bluish because they involve blood vessels in deeper layers of the skin. Hemangiomas grow rapidly during the first 6 months or so of life, but usually shrink back and disappear by the time a child is 5 to 9 years old. The most common pigmented birthmarks are café-au-lait spots, Mongolian spots, and moles: Café-au-lait spots. They are most common on darker skin, such as on children of Asian, American Indian, African, Hispanic, and Southern European descent. Most people get moles at some point in life. Large or giant congenital nevi are more likely to develop into skin cancer (melanoma) later in life. Smaller moles may have a slight increase in risk. birthmarks birthmarks