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Many people carry birthmarks, or body blemishes, in one of two forms: pigmented birthmarks or red birthmarks. Pigmented are more commonly referred to as light tan or cafe-au-lait spots. They are generally harmless and are called “pigmented birthmarks” because of their various shades of coloring from light brown or black to bluish or blue-grey. In their most drastic form, pigmented birthmarks are more pronounced, dark brown clusters of raised skin called “moles” or “hairy moles” -- or their more clinical name of, “nevi”.

Most moles or nevi appear after birth and are rarely a health threat. Many people decide to remove moles for cosmetic reasons. Once gone they rarely grow back. Even so, it’s a good idea to check large, dark brown moles regularly. If there is a sudden and significant color change, if they bleed or become ulcerous, or if there’s loss of hair on or around a 'hairy' mole, it’s a good idea to seek medical advice. “Congenital nevi”, however, form before birth, and should be more closely monitored by a doctor or dermatologist because these have a higher incidence of becoming skin cancer (malignant melanoma).

The formation of pigmented birthmarks has to do with “melanin”, a biological colorant found in the tissue of all living things. Melanic pigmentation is important in various ways: it’s a shield against ultraviolet light, it aids in absorption of heat (necessary for cold-blooded animals), it helps certain species conceal themselves from predators, and it filters harsh light within the retina. If there’s a complete absence of melanin in skin, fur, feathers, or the eyes, the condition is known as “albinism”. Pure white rabbits, mice, certain cat breeds, and in rare cases, humans, fall victim to this mutation, and are called “albinos”. All albinos are “photophobic”, that is, they must shield themselves against direct sunlight. Their eyes usually appear pink because the blood vessels of the retina are exposed. In humans, albinism appears to be hereditary. In animals, the condition is evident in most species, and leaves those afflicted weak and easy prey. Albino animals left on their own rarely survive for long in their natural environment.

Red birthmarks, or “capillary hemangioma”, are related to vascular skin changes. Such blemishes are more commonly referred to as salmon patches, stork bites, strawberry marks, or the more serious “port wine stain”. These reddish marks are caused by an over-abundance of blood vessels at the site where they appear, either before or after birth. Strawberry birthmarks seem to be the most common, especially among women. They grow very quickly, then stay the same size until they eventually disappear on their own, usually by the time the child has reached 9-10 years of age.

Port wine stains are by far the most noticeable and disfiguring of any birthmarks and are always evident at birth. They are in most cases flat against the rest of the skin and composed of dilated blood vessels. The coloring ranges from pale pink to very dark purple. The face, neck and top of the shoulder or chest are the most common locations, although port wine stain birthmarks have been known to afflict much larger portions of the body. In these more serious cases psychological trauma occurs. Recent treatment involving the use of laser therapy has made it easier for sufferers to live with their condition. Because the nervous system is involved, however, a port wine stain can eventually re-appear, therefore treatment must be maintained for life.

Birthmarks even grow inside the body. These are much more difficult to detect and can involve the liver, intestines, airway or the brain. Jaundice in a new-born baby may be a sign of an internal birthmark around the liver. Blood in the stool, a croupy cough, or other breathing problems should also be immediately investigated. Doctors usually perform ultrasounds to see exactly what is going on and to determine the most effective treatment.