How Do I Know if a Mole Is Cancer?

How Do I Know if a Mole is Cancer?Moles are growths on the skin that are usually brown or black. Moles can appear anywhere on the skin, alone or in groups.  Most moles appear in early childhood and during the first 30 years of a person's life. It is normal to have between 10-40 moles by adulthood.

As the years pass, moles usually change slowly, becoming raised and/or changing color. Often, hairs develop on the mole. Some moles may not change at all, while others may slowly disappear over time.

What Causes a Mole?
Moles occur when cells in the skin grow in a cluster instead of being spread throughout the skin. These cells are called melanocytes, and they make the pigment that gives skin its natural color. Moles may darken after exposure to the sun, during the teen years, and during pregnancy.

Types of Moles
Congenital nevi are moles that appear at birth. Congenital nevi occur in about one in 100 people. These moles may be more likely to develop into melanoma (cancer) than are moles that appear after birth. A mole or freckle should be checked if it has a diameter of more than 7 mm or any characteristics of the ABCDEs of melanoma.

Dysplastic nevi are moles that are larger than average (larger than a pencil eraser) and irregular in shape. They tend to have uneven color with dark brown centers and lighter, uneven edges. People with dysplastic nevi may have more than 100 moles and have a greater chance of developing melanoma, a serious form of skin cancer. Any changes in a mole should be checked by a dermatologist to detect skin cancer.

The ABCDEs
The following ABCDEs are important characteristics to consider when examining your moles. If a mole displays any of the signs listed below, have it checked immediately by a dermatologist. It could be cancerous.

  • Asymmetry. One half of the mole does not match the other half.
  • Border. The border or edges of the mole are ragged, blurred, or irregular.
  • Color. The color of the mole is not the same throughout or has shades of tan, brown, black, blue, white, or red.
  • Diameter. The diameter of a mole is larger than the eraser of a pencil.
  • Evolution. The mole is changing in size, shape, or color. 

Examine your skin with a mirror or ask someone to help you. Pay special attention to areas of your skin that are often exposed to the sun, such as hands, arms, chest, neck, face, and ears. If your moles do not change over time, there is little reason for concern. Most moles are not dangerous. The only moles that are of medical concern are those that look different than other existing moles or those that first appear after age 20.

If you notice changes in a mole's color, height, size, or shape, you should have a dermatologist (skin doctor) evaluate it. You also should have moles checked if they bleed, ooze, itch, appear scaly, or become tender or painful.  If you see any signs of change in an existing mole, if you have a new mole, or if you want a mole to be removed for cosmetic reasons, talk to your dermatologist.