- Birthmarks are very common and usually not harmful. Some, however, may indicate an increased risk for certain health conditions.
- There are two types of birthmarks – vascular and pigmented – and both come in a variety of colours and shapes.
- Though some types may be hereditary, experts don’t really know what causes most birthmarks.
- Visit INSIDER’s homepage for more stories.
If you don’t have a birthmark, you probably know someone who does. These unique skin features can look like freckles, moles, scars, or even dabs of paint. But what exactly are they?
INSIDER turned to dermatologists and other doctors to answer just that.
There are two main types of birthmarks
There are two main categories of birthmarks: vascular birthmarks and pigmented birthmarks.
“Vascular birthmarks are an overgrowth of small skin blood vessels that end up giving red, pink, or blue colour to the skin area involved,” family medicine physician Dr. Viquar Mundozie told INSIDER.
The second type of birthmark is called a pigmented mark. Unlike vascular marks, which are caused by having more blood vessels than normal in a certain area, pigmented birthmarks have to do with the distribution of colour in your skin.
“Pigmented birthmarks are due to over-secretion of the skin pigment melanin or clustering of pigment cells called melanocytes in the area involved,” Mundozie explained. “This gives the mark an appearance that is different than the rest of the skin.”
How both vascular and pigmented birthmarks appear varies widely between people. Many lighten over time, but some can actually become more prominent.
Vascular birthmarks include so-called port wine stains, salmon patches, and strawberry marks
Vascular birthmarks can appear in different shapes and sizes. Some of the most common types even have special names.
“Port wine stains,”formally known as capillary malformation, may occur when the nerves that are in control of the constriction and dilation of capillaries become damaged, Dr. Hardick Soni, medical director of Ethos Spa, Skin, and Laser Center in New Jersey, told INSIDER. They can appear dark red or purple, and sometimes enlarge as a child grows. They can also be sensitive to hormone changes, so may grow or become more prominent during puberty, pregnancy, or menopause.
“Salmon patches” are pink marks that occur in about half of all babies, according to the U.K.’s National Health Service, or NHS. They usually appear on the face and neck and can get darker when a baby cries due to increased blood flow. Most salmon patches fade within a few months or years.
“Strawberry marks” are raised bumps that can take on a pink or red colour, according to NHS. They often grow in size over the course of the first six months of a baby’s life, but usually shrink and vanish by the time the child is about 7.
Pigmented birthmarks are caused by irregular skin pigment production
Pigmented birthmarks can vary in colour and may appear as brown, grey, blue, or black marks. Common names for different types of pigmented birthmarks are Mongolian spots, congenital melanocytic nevi, and cafe-au-lait spots.
“Cafe-au-lait spots” are brown or beige areas on the skin. Though they’re named for the French term for “coffee with milk,” they can appear as deep brown spots on darker skin. According to the American Academy of Dermatologists, or AAD, these marks often fade with age but don’t usually disappear completely.
“Mongolian spots” often appear on the backs or bottoms of children with a darker skin tone. They can appear blue or even grey and may resemble bruises. These marks often fade, but they can sometimes last a lifetime.
Some birthmarks may be genetic, but doctors don’t actually know exactly why most appear
Your distinctive birthmark may be a family heirloom, but most are thought to occur by chance, according to the Stanford Children’s Health website. Though experts speculate that some birthmarks are hereditary, they’re still not really sure why they form, AAD reports.
“Some birthmarks run in families,” Soni said. “However, scientists are not completely sure why birthmarks only affect some babies, or why they develop in the first place.”
Non-hereditary genetic mutations are responsible in some cases. There is a clear link between babies born with the vascular disorder Klippel-Trenaunay syndrome and the appearance of port wine stains, but not every baby with port wine stains has the condition. Port wine stains are also a telltale sign of the rare neurological disorder Sturge-Weber Syndrome, but again, the syndrome doesn’t affect every child with these types of marks.
Some birthmarks can raise your risk of cancer or signal potential health problems
Though the vast majority of birthmarks are nothing to worry about, some may indicate an underlying health condition or elevate your risk of future health problems.
Congenital melanocytic nevi, for instance, are moles that appear at birth or within the first few years of life, Mundozie said. They’re a type of pigmented birthmark and are usually flat at first, though they can become raised or hairy over time, according to the British Association of Dermatologists, or BAD. These types of congenital moles are more likely than normal skin to develop into skin cancer. The larger the mole, the greater the risk, according to BAD.
Cafe-au-lait spots are quite common, but having more than six before age 5 might indicate a serious disorder. Neurofibromatosis is a genetic condition that causes tumours to grow along your nerves and often produces skin changes, including cafe-au-lait spots and clusters of freckles.
It’s a good idea to regularly see your primary care physician or a dermatologist to keep an eye on any birthmarks, especially if you have a congenital mole that begins to change shape, itch, or bleed.
Business Insider Emails & Alerts
Site highlights each day to your inbox.