Skin problems health centre

Skin conditions: Pigmented birthmarks

Birthmarks are coloured skin spots that are either present at birth or develop shortly after birth. Birthmarks can be many different colours, including brown, light brown, black, pale blue, pink, white, red, or purple. Some birthmarks are only colourations of the surface of the skin; others are raised above the surface of the skin or extend into the tissues under the skin.

What causes birthmarks?

The cause of most birthmarks is unknown. Most birthmarks are not inherited. Many old wives tales and myths exist about the causes of birthmarks, but none of these stories have been proven to explain the true causes of birthmarks.

Do birthmarks need to be treated?

Most birthmarks need no treatment. They often fade as a child grows older. However, some birthmarks may need treatment because of their location. For example, a raised birthmark near a child's eye may interfere with the ability to see. In rare cases, birthmarks are associated with other conditions, such as growths on the liver, lungs, stomach, or intestines.

Types of birthmarks

There are two main categories of birthmarks - red birthmarks and pigmented birthmarks.

Red birthmarks are coloured, vascular (having to do with blood vessels) skin markings that develop before or shortly after birth. Pigmented birthmarks are skin markings that are present at birth. The marks may range from brown or black to bluish or blue-grey in colour.

Types of pigmented birthmarks

• Mongolian spots are usually bluish and appear as bruises. They often appear on the buttocks and/or lower back, but they sometimes also appear on the torso or arms. The spots are seen most often in people who have darker skin.
• Pigmented nevi (moles) are growths on the skin that are usually flesh-coloured, brown or black. Moles can appear anywhere on the skin, alone or in groups. Moles occur when cells in the skin grow in a cluster instead of being spread throughout the skin. Moles may darken after exposure to the sun, during teenage years and during pregnancy.
• Congenital nevi are moles that are present at birth. These birthmarks have a slightly increased risk of developing skin cancer depending on their size. Larger congenital nevi have a greater risk of developing skin cancer than do smaller congenital nevi. All congenital nevi should be examined by a doctor and any change in the birthmark should be reported.
• Cafe-au-lait spots are milky coffee-coloured or light brown spots that are usually oval in shape. They usually appear at birth but may develop in the first few years of a child's life. Cafe-au-lait spots may be a normal type of birthmark, but the presence of several cafe-au-lait spots larger than a 2p coin may occur in neurofibromatosis (a genetic disorder that causes abnormal cell growth of nerve tissues).