Causes and When to Be Concerned


Most people have at least one mole. Moles refer to the presence of pigment-producing cells (melanocytes), in your skin. Moles are more common for people with pale skin.

Moles are also known as nevus (plural nevi). It derives its name from the Latin word birthmark.

The cause of moles isn’t well understood. It’s thought to be an interaction of genetic factors and sun damage in most cases.

In childhood and adolescence moles often appear. They change in size and colors as you get older. When hormone levels are changing, like during pregnancy, new moles often appear.

Moles typically measure less than 1/4 inches in diameter. The mole color ranges between pink, dark brown, or black. They can be found anywhere, either alone or together.

Most moles are benign and non-cancerous. New moles in an adult are less likely to be cancerous than old ones.

If a new mole appears when you’re older, or if a mole changes in appearance, you should see a dermatologist to make sure it’s not cancerous.

There are many types, with different appearances and risk factors, of moles.

Congenital moles

These moles are known as birthmarks. They can be large, small, or even very colorful. Congenital moles affect between 0.2 percent and 2.1 per cent of infants.

If the child is between 10 and 12 years old, certain birthmarks can be treated for cosmetic reasons. There are many treatment options:

  • Operation
  • skin resurfacing (dermabrasion)
  • Excision of the top skin layers by skin shaving
  • Chemical peel to lighten
  • Laser ablation for lightening


Adults with larger congenital moles are at greater risk of developing malignancy (4 to 6 percent lifetime chance). Doctors should examine any changes in the size, color, form, or pain caused by birthmarks.

Acquired moles (also referred to as common moles).

Acquired moles are those that appear on your skin after you’re born. They’re also known as common moles. They can appear on any part of your skin.

People with fair skin may have between 10-40 of these moles.

Common moles include:

  • Oval or round
  • Sometimes, flat, sometimes slightly raised, or dome-shaped
  • Smooth or rough
  • One color (tan or brown, black, red pink, blue or skin-colored).
  • Unchanging
  • Small (1/4 inch or smaller; about the size of a pencil eraser).
  • You may have hairs

Moles that have darker skin tones or darker hair may appear darker than those with lighter skin.


If you have more than 50 common moles, you’re at a higher risk for skin cancer. But it’s rare for a common mole to become cancerous.

Atypical moles (also known dysplastic nevi).

You can find unusual moles anywhere on your body. Atypical moles most often appear on the trunk. However, they can also be found on the neck, scalp, and head. They are rarely found on the face.

Some benign atypical moles could have the same characteristics of melanoma (a form of skin cancer). So, it’s important to have regular skin checks and to monitor any changes in your moles.

Cancerous potential exists for atypical moles. But it’s estimated that only 1 in 10,000 atypical moles turn into cancer.

Because of their appearance, atypical moles have been characterized as the “ugly ducklings” of moles.

Atypical moles can be:

  • Uneven in form with irregular borders
  • Variable in color: Mixtures of brown, red, pink, and tan
  • pebbled in texture
  • Larger than a pencil eraser. 6 millimeters or greater
  • Fair-skinned people are more likely to have this problem
  • People with high sun exposure are more likely to have skin cancer


If you are a smoker, your chances of developing melanoma are higher.

  • There are four to five atypical moles
  • A blood relative with melanoma
  • Melanoma was previously treated.

Family members with a high number of unusual moles may be at risk for familial atypical multi-mole melanoma syndrome (FAMMM). Your risk of melanoma is 17.3 times higher that people who don’t have FAMMM syndrome.

The cause of a new mole that appears in adulthood isn’t well understood. The cause of new moles can be benign, or they could be cancerous. Melanoma causes are well studied, but there’s little research on what causes benign moles.

There are likely to be genetic mutations. According to a 2015 study, genetic mutations in the BRAF gene were found in 78 percent benign acquired moles.

BRAF mutations have been linked to melanoma. But the molecular processes involved in transforming a benign mole to a cancerous mole aren’t yet known.

It is well-known that UV light can cause DNA damage and may lead to melanoma or other skin cancers. Sunburns can be caused by sun exposure in childhood, young adulthood, or later on when skin cancer is more likely to develop.

There are several reasons you might have a new mole.

  • Growing older
  • Fair skin with light or dark hair
  • Family history of atypical moles
  • Drugs that suppress your immune system will cause an allergic reaction
  • Other drugs such as antidepressants, hormones or antibiotics may cause a different response.
  • Genetic mutations
  • sunburn, sun exposure, or tanning bed use

New moles are at greater risk of becoming cancerous. A 2017 case study review found that 70.9 per cent of melanomas originated from a new tumor. If you’re an adult with a new mole, it’s important to have it checked by your doctor or a dermatologist.

To check if an old mole is changing or if a new one appears in adulthood, visit a doctor.

Seek medical attention immediately if your mole is bleeding, itching, painful, or oozing.

Melanoma, the most severe form of skin cancer, is the most deadly. But new moles or spots can also be basal cell and squamous cancers. These typically appear on areas that are directly exposed to the sun like your neck, face, and head. They’re easily treatable.


Here’s an ABCDE melanoma guide about what to look for, developed by the American Academy of Dermatology:

  • Asymmetrical shape. Each mole is unique in its own way.
  • Border. The borders of the mole are irregular.
  • Color. The mole is now a different color, or has multiple or mixed colors.
  • Diameter. The mole gets larger — more than 1/4 inch in diameter.
  • The Evolution. The mole’s size, color, shape and thickness change constantly.

Self-checks of the skin

Checking your skin regularly can help you spot mole changes. The majority of skin cancers are found in areas that are visible to the naked eye.

It’s uncommon to find melanomas in parts of the body protected from the sun. The arms and legs are the most common areas for melanoma among women.

The most common sites for melanoma in men are the neck, back, trunk, head, and neck.

Non-Caucasians are more at risk of developing melanoma. However, the locations of melanoma are different for people with skin color. The following are some of the more common spots for melanoma to non-Caucasians.

  • The soles
  • The palms
  • Between your fingers and toes
  • Unter den Fingernails oder Toenails

According to a 2000 study, self-checks can sometimes miss moles changes.

A doctor should check any moles that develop in adulthood. It’s recommended that people have a skin check by a dermatologist yearly. If you’re at risk for melanoma, your doctor may recommend a skin check every six months.

If you’re concerned about your mole and don’t already have a dermatologist, you can view doctors in your area through the Healthline FindCare tool.

Seek medical attention immediately if you notice a mole changing, particularly if it meets the criteria of the ABCDE guide.

It is important to be early in melanoma detection. This can lead to significant survival advantages. Melanoma is diagnosed early and has a 10-year survival rate of 93 percent.

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