Skin Conditions: Pigmented Birthmarks

Medically Reviewed by Debra Jaliman, MD on May 10, 2023
4 min read

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

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

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 their ability to see. In rare cases, birthmarks are associated with other conditions, such as growths on the liver, lungs, stomach, or intestines.

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

Red birthmarks are colored, 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. Their color ranges from brown or black to bluish or blue-gray.

Congenital melanocytosis, previously called Mongolian spots, usually are bluish and look like bruises. They often appear on the buttocks and/or lower back, but they sometimes also appear on the trunk or arms. The spots are seen most often in people who have darker skin.

Pigmented nevi (moles) are growths on the skin that usually are flesh-colored, 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 the teen years, while taking some birth control pills, and during pregnancy.

Congenital nevi are moles that are present at birth. These birthmarks have a slightly increased risk of becoming 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 health care provider and any change in the birthmark should be reported.

Cafe-au-lait spots are light tan 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 quarter may occur in neurofibromatosis (a genetic disorder that causes abnormal cell growth of nerve tissues) and other conditions.

The cause of pigmented birthmarks is not known. However, the amount and location of melanin (a substance that determines skin color) determines the color of pigmented birthmarks.

Symptoms of pigmented birthmarks include skin that is abnormally dark or light, or bluish, brown, black or blue-gray in color. Discolorations of the skin may vary in size and can be smooth, flat, raised or wrinkled. Pigmented birthmarks may increase in size, change colors, become itchy, and may occasionally bleed. If  they do, they should be seen by a dermatologist as they may require a biopsy

In most cases, health care professionals can diagnose birthmarks based on the appearance of the skin. If a mole exhibits potentially cancerous changes, a biopsy may be performed.

In most cases, no treatment is needed for the birthmarks themselves. When birthmarks do require treatment, however, that treatment varies based on the kind of birthmark and its related conditions.

Large or prominent moles that affect appearance and self-esteem may be covered with special cosmetics. Moles can also be removed surgically.

Since there is an increased risk of skin cancer in congenital nevi, see a doctor if you notice a change in color, size, or texture of a mole or other skin lesion. Also, see a doctor right away if there is any pain, bleeding, itching, inflammation, or ulceration of a congenital mole or other skin lesion.

There is no known way to prevent birthmarks. People with birthmarks should use a good quality sunscreen with an SPF of 30 or higher when outdoors in order to prevent complications.