Cancerous Moles: Signs & Self-Examination 

Moles are normal skin growths found in areas of the skin that are usually exposed to the sun. Most adults have about 10 to 40 moles, which may begin to appear at birth or develop later in childhood and up to mid-adulthood.

Some people develop cancerous moles that may look similar to common moles. However, these cancerous cells can spread throughout the body and pose danger to one’s health. Find out more about cancerous moles and how to manage them.

Common Moles vs. Cancerous Moles

1. Common moles

Common moles are composed of clusters of pigmented cells called melanocytes. Moles or nevi (nevus, singular) are usually less than 5 mm in diameter, oval or round in shape, with distinct borders or edges.

Location: They are not usually found in hidden areas like the scalp or buttocks, and they may appear darker in color in people with dark skin and hair.

2. Cancerous moles

Common moles rarely become cancerous. Cancerous moles consist of cancer cells that develop from melanocytes, which are mostly found in the skin surface. These new growths are also called melanoma, a skin cancer that can invade other tissues and organs of the body.

Location: Cancerous moles are often found in the back, head, and neck of men, while they occur more often in the back or lower legs of women. They are more likely to develop in fair-skinned individuals than dark-skinned people, but when they do develop in the latter, the cancerous moles are usually found in less exposed areas such as the palms, soles, and under the nails.

Signs of Cancerous Moles

Cancerous moles may appear as new skin growths or they may be seen as a change in an existing mole. Cancerous moles have varied appearances, and they may have some or all of the features to be mentioned below. It is easy to remember the signs of cancerous moles or melanoma by using the ABCDE rule for their features:


A for Asymmetry. This means that the shape of one side of the mole does not match the other side.


B for Border. Irregularities in the borders of a mole, blurring of outlines and spread of mole pigment in surrounding skin can be a sign that it is cancerous.


C for Color. Uneven colors or pigmentation may suggest melanoma, and these colors may include brown, tan, black, white, blue, red, gray and pink.


D for Diameter. A mole that enlarges to more than 6 mm (or ¼ inch) in a short period of time must be suspected to be cancerous.

E for Evolving. Rapid changes in a mole that take place over a few weeks or even months may be a sign of cancer.

Risk Factors of Cancerous Moles

There are some factors that increase one’s risk for developing cancerous moles, such as:

  • Dysplastic nevus. A nevus or mole that does not look like a common mole is known as a dysplastic nevus or atypical mole. Although it does not have the characteristics of a common mole, it does not contain cancer cells. However, sometimes these can also develop into cancerous moles.
  • Number of common moles. Having more than the usual number of moles (>50) increases your chance of having cancerous moles.
  • Exposure to sunlight. Ultraviolet (UV) radiation from the sun’s rays can cause permanent skin damage. An increased amount of exposure to UV rays escalates one’s chance for developing cancerous moles.
  • Artificial sources of UV radiation. UV radiation from tanning booths and sunlamps also cause skin damage that leads to cancer. One’s risk greatly increases when these are used before the age of 30.
  • Personal and family history. A personal history of having melanoma or a positive family history for the condition increases one’s risk for developing cancerous moles.
  • Skin condition. Pale or fair-skinned individuals have skin that burns easily, and is therefore damaged easily, increasing the likelihood for skin cancer. These people usually have gray or blue eyes, blonde or red hair, and numerous freckles.
  • Medical conditions and medications. Certain conditions and medications make the skin more susceptible to sunburn and skin damage. Other conditions or drugs can also weaken the immune system, which increases the chance for developing cancerous moles.

Self-Examination for Cancerous Moles

To check yourself for cancerous moles, follow these steps:

  • Check your skin from head-to-toe after a shower or bath, using a full-length mirror.
  • Inspect your scalp, face, neck, and ears. You can use a comb to inspect the scalp better or ask someone else to look at portions you cannot see in the mirror.
  • Start by looking at the front and back of your body, and then raise your arms to inspect the left and right sides of the body.
  • Carefully look for any new moles or changes in moles in even under your fingernails, palms, hands, and arms, including the undersides.
  • Next check the front, back, and sides of the legs, buttocks, including the genital areas.
  • Examine your feet, checking the toenails, soles, and spaces between toes.

It may be wise to keep track of the number and appearance of your moles by taking photos. You can also monitor them by taking note of the dates, and track any changes. If a mole changes in shape, color, size, or exhibit ABCDE features, it is best to see a doctor. Report the appearance of any new mole which you think may look suspicious.

Diagnosis, Treatment and Prevention of Cancerous Moles

1. Diagnosis

The diagnosis of cancerous moles consists of:

  • Regular skin examination, which may be done by yourself and by a doctor.
  • Biopsy of a suspicious mole, which involves microscopic examination of a tissue.

2. Treatment

Treatment of cancerous moles involves removal of the mole followed by cosmetic care, which may be done in the doctor’s office.

  • Mole removal may involve surgical excision using a scalpel or sharp puncher, or surgical shaving using a blade to remove smaller moles.
  • Cosmetic care may be needed to conceal the mole. This may consist of using make-up to cover the mole and hair removal if there are unsightly hairs growing from the mole.

3. Prevention

Prevention of skin cancer is the best way to avoid cancerous moles. This involves:

  • Regular skin examination. Use the ABCDE guide.
  • Avoiding overexposure to sunlight and tanning salons. Stay out of the sun during peak hours (10 am to 4 pm) when UV rays are most intense.
  • Using sunscreen regularly. Apply sunscreen with SPF 15 or more, 30 minutes before sun exposure. Reapply this every 2 hours especially during prolonged activities under the sun.
  • Covering up. Covering up exposed parts of the body with hats, appropriate clothes, sunglasses, etc