A nevus, or mole, is an area of growth on the skin. Some moles are present at birth, while others develop over the course of your lifetime. Many of the moles that develop during adulthood are related to sun exposure and effects on melanin production.

While mostly thought of as brown, moles can come in a variety of colors, including red, pink, and flesh-colored. Some may also have hairs that grow from them. Most moles are benign, but it’s still important to keep an eye on them for any changes that could indicate cancer growth.

There are three main types of moles:

Congenital moles

Congenital moles are present at birth, which affect about 1 out of every 100 babies, according to the American Osteopathic College of Dermatology (AOCD). These can be flat and vary in color, but most congenital moles don’t become cancerous.

Acquired moles

Acquired moles are those that you develop later in life. Most of these are brown and appear due to sun damage. They’re also round without any significant changes as you age. These types of moles can also darken with age, but not necessarily turn into melanoma.

Atypical moles

Unlike congenital and acquired nevi, atypical moles are at a greater risk of becoming cancerous. The AOCD estimates that 1 in 10 people in the U.S. has at least one atypical nevus.

Unlike congenital and acquired moles, atypical moles are slightly larger and have irregular-shaped borders. While melanomas are classified as darker moles, atypical nevi can come in a variety of shades. Learn more about what melanoma looks like.

Simply put, moles are caused by abnormal growth cells in the skin. However, abnormal growth doesn’t always mean cancer. Overall, moles are extremely common, with the American Academy Dermatology (AAD) estimating an average of 10 to 40 moles per person.

Some people are born with moles, as is the case with congenital nevi. You can also develop moles during childhood and early adulthood. Sun exposure and other drivers behind aging skin can lead to nevi as an older adult.

Some moles can become cancerous, but the majority are harmless — this is why it’s important to always get a dermatologist’s take on any moles in question.

You might decide to have a mole removed for a couple of reasons. Some moles can be bothersome due to size and location. Others might need to be removed because of a doctor’s orders due to melanoma concerns. You should never remove a mole at home on your own.

A doctor might remove a skin mole by either shaving or surgical cutting. A dermatologist may shave off smaller moles but recommend cutting for larger or cancerous ones. Depending on the size of the removal area, you may need stitches. It can also take two appointments to completely remove a mole.

It’s a myth that removing all your moles will prevent you from getting skin cancer.

Atypical moles

Technically, all atypical types of moles are precancerous, but most of these moles don’t actually turn into cancer. Melanoma, the most dangerous type of skin cancer, usually develops from normal skin and not a pre-existing mole.

Mole removal and scars

A mole removal treatment will leave some scarring. Scars may be treated with chemical peels, laser treatments, and other methods to lower pigmentation after they’ve healed. Follow your dermatologist recommendations, but know you’ll likely see remnants of the scar. Read more about how typical moles look compared to atypical moles.

Dermatologists recommend an annual skin checkup. At this time, they’ll look at any existing moles for changes, as well as any potential cancerous growth. If you see any concerning changes to your skin in between your annual checkups, you should make an appointment.

Some of the changes that warrant a doctor’s check include:

You may also be at a higher risk of cancerous skin spots if you have more than 50 acquired moles, according to the AAD.

When it comes to looking out for the signs of skin cancer, the AAD reminds us to remember the ABCDEs of melanoma:

  • Asymmetry
  • Border: irregular and sometimes poorly defined
  • Color: can vary in same mole
  • Diameter: usually 6mm or larger
  • Evolving

What to look for where a mole used to be

You’ll also want to look out for signs of a returning mole after removal. While not necessarily cancerous, the risk of melanoma can be greater if the original mole had cancer cells. Monthly self-checks help you notice changes that may merit an appointment with a dermatologist.

Skin care is important to your overall health and it’s worth keeping in mind that moles are a part of your skin, too. Aside from regular cleansing and moisturizing, you’ll want to wear sunscreen every single day. Don’t skip around the moles of your skin — they need protection of at least SPF 30 like the rest of your skin.

The American Cancer Society suggests full sun protection on a regular basis.

Skin care where a mole used to be

If you’ve had any moles removed, it’s also important to give the remaining skin some extra TLC. Sunscreen can help prevent scars from darkening and making them more noticeable.

It’s also helpful to keep your scar clean and moisturized. If the area is still healing, keep it protected and use petroleum jelly. Once your skin has healed, massaging your scar can also help flatten and smooth out the surface.

Moles, or nevi, are commonplace part of the skin. Moles are much more complex than simply being cancerous or benign bumps on your body. They’re more likely to develop in later childhood and adulthood, but you can be born with moles, too.

Most moles don’t become cancerous — but when they do, they can be life-threatening if not caught early. Knowing your own skin and doing self-checks are important.

It’s also important to see your dermatologist regularly for checkups and to notify them if you see any sudden changes in your skin.