Melanoma is a type of skin cancer. Melanocytes contain a pigment that gives moles their distinctive coloring. Moles can be benign or cancerous. Cancerous moles, such as melanomas, develop as a result of genetic mutations. The exact cause of benign moles remains unknown. Common moles can appear at birth or later in childhood. These moles usually appear on areas of the skin that a person exposes to sunlight.
A common mole typically has a round, symmetrical appearance with a smooth surface and a defined border. Common moles are relatively small, measuring less than 5 millimeters mm in diameter. These moles rarely develop into cancer. However, people who have more than 50 common moles may have a higher chance of developing melanoma, according to the National Institutes of Health NIH. Congenital moles, or birthmarks , are present at birth. Congenital moles can vary drastically in size with some being quite large.
However, figures may vary from study to study. Atypical moles, or dysplastic nevi, can develop anywhere on the body and usually appear larger than other mole types. Their color and texture can vary, and they usually have an uneven border that fades into the surrounding skin. According to the American Cancer Society , some atypical moles may become cancerous. However, most atypical moles do not develop into melanomas. Since atypical moles may show some similar characteristics to melanoma, people should visit their dermatologist to be sure that there are no concerns.
Page last reviewed: 04 February Next review due: 04 February Types of birthmark There are many different types of birthmark. Flat, red or pink areas of skin salmon patches or stork marks Credit:. Information: Find out about other types of birthmark: The Birthmark Support Group has information about other types of birthmark and getting help and support. Non-urgent advice: See a GP if:.
Because melanoma, the most-serious skin cancer, can develop in a mole, this birthmark should be checked by a dermatologist. Mongolian spot on buttocks. What it looks like: Often looking like a bruise, this birthmark may be light blue, dark blue, or blue gray. This birthmark occurs in all races. Where it usually appears on the body: Most appear on the lower back or buttocks, but it can show up anywhere on the skin.
These often go away by the time a child is 3 to 5 years old. A few people still have this birthmark as adults. Port-wine stain on a child's arm and upper chest. As the child grows, so will this birthmark. In time, the birthmark tends to thicken and darken. As it thickens, the texture can change. Ridges may develop. Sometimes, the birthmark feels like cobblestones on the skin. Where it usually develops on the body: A port-wine stain usually develops on the face; however, it can appear anywhere on the skin.
Without treatment, this birthmark remains on the skin for life. Mikhail Gorbachev, the former president of the Soviet Union, has a port-wine stain. Nevus sebaceous on child's scalp. When it develops on the scalp of a newborn, this birthmark often looks like a slightly raised, hairless or nearly hairless patch. As your child grows, this birthmark may stay the same or change. It may thicken. You may notice the birthmark changes color, becoming slightly yellow or orange.
The surface can feel pebbly or warty. Where it usually develops on the body: This birthmark usually appears on the scalp or face. Occasionally, it develops on the neck or another area of the body. White spot birthmark. This spot can be raised or flat. It may be round, oval, or another shape. Some are leaf shaped. Where it usually appears: Most develop on the chest, abdomen, back, or buttocks. They can also appear anywhere else on the skin.
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