Moles are incredibly common, with most adults having between 10 and 40, according to the National Cancer Institute (NCI). The technical term for a mole is nevus (plural: nevi), which is the Latin word for birthmark. These concentrations of pigment-producing cells in the skin usually appear during childhood and adolescence (ages 0 to 19), changing in size and color as you age. New moles may also emerge when hormone levels change, such as during pregnancy. Sun damage and genetics may also play a role. However, the main cause of moles is not well understood.

The majority of moles are less than 1/4 inch in diameter and range from light pink to dark brown or black in color. They can appear anywhere on your body. While most moles are benign (noncancerous), new moles in adults have a higher chance of becoming cancerous than old moles from childhood and adolescence.

If you have a new mole or noticed changes in the appearance of an old one, consider seeing a dermatologist to ensure it’s benign.

What Are the Different Types of Moles?

The three types of moles are categorized by when they emerge; their appearance; and their risk of becoming malignant (cancerous). They include:

Congenital Moles

Also called birthmarks, congenital moles appear in different sizes, shapes, and colors. Between 0.2 and 2.1 percent of infants are born with this type of mole. Large congenital moles have a 4 to 6 percent lifetime risk of becoming cancerous in adulthood. As such, any changes in a birthmark – including size, shape, color, or if pain occurs – should undergo a medical examination.

Birthmarks may be removed for health and cosmetic reasons. Treatment options include:

Surgical excision
Skin shaving
Skin resurfacing (dermabrasion)
Laser ablation for lightening
Chemical peel for lightening

Atypical Moles

These moles can appear anywhere on the body. Also called dysplastic nevi, while most of these moles develop on the chest, abdomen, pelvis, and back (upper and lower torso), they can also form on your head, scalp, and neck.

Nicknamed the “ugly ducklings” of moles due to their appearance, atypical moles are:

Irregular in shape with uneven borders
Pebbled in texture
Varied in color: mixes of brown, tan, pink, and red
Around 6 millimeters or more in size
More common in people with fair skin
More prevalent in people who have high sun exposure

Benign dysplastic nevi have some of the same characteristics as melanoma cancer. If you have atypical moles, it’s important to schedule regular skin checks with your dermatologist to monitor any changes in them. These moles have the potential to become cancerous, although only 1 in 10,000 dysplastic nevi become malignant.

Your risk of developing melanoma is greater if you have:

Four or more atypical moles
A family history of melanoma
Had a previous diagnosis of melanoma

If your blood relatives have a lot of atypical moles, you may have familial atypical multiple mole melanoma (FAMMM) syndrome, which makes your risk of melanoma 17.3 times higher than those who do not have FAMMM syndrome.

Common Moles

Common or acquired moles arise at any time after birth. They can appear anywhere on the body, usually among people with fair skin.

Most common moles are:

Round or oval
Flat, raised slightly, or sometimes dome-shaped
Rough or smooth and may have hairs
One color (brown, tan, black, pink, red, blue, or skin-colored)
Small, around 1/4 inch or less

If you have over 50 common moles, your risk for skin cancer is higher, according to the American Academy of Dermatology Association. However, acquired moles becoming cancerous is rare.

What Causes New Moles to Appear?

The reason why new noncancerous moles appear in adulthood remains somewhat of a medical mystery. Although the scientific community has heavily researched melanoma’s causes, there is no clear explanation as to why benign moles appear.

As for cancerous new moles, the cause may be a combination of the following:

Genetic mutations: A 2015 study revealed that genetic mutations in the BRAF gene were detected in 78 percent of noncancerous acquired moles. BRAF mutations are associated with several cancer types, including melanoma. The molecular functions responsible for transforming a benign mole into a malignant mole, however, remain unknown.
Excessive sun exposure: The interaction of natural or artificial ultraviolet (UV) light with human DNA causes genetic damage that can lead to the development of melanoma and other skin cancers. Sun exposure can occur during childhood and only progress into skin cancer years later in adulthood.

Other reasons new moles appear on the skin are:

Increasing age
Having fair skin and naturally light- or red-colored hair
Response to medication that suppresses the immune system
Response to antibiotics, hormone replacement therapy, or antidepressants
Family history of atypical moles
Genetic mutations
Frequent sunburns
Excessive sun exposure and sunlight or sunbed tanning

When to See a Doctor

New moles have a higher chance of becoming cancerous than old moles. An analysis of clinical studies concluded that new moles accounted for 70.9 percent of melanomas. If you are an adult with a new mole on your face or body, schedule a screening with your dermatologist as soon as possible.

If one or more of your moles has been changing, especially if any of them meets the criteria in the ABCDE guide, see your physician right away.

In most cases, doctors recommend annual or bi-annual skin checks depending on how high your risk of developing skin cancer is, or if you have a personal history of skin cancer. The good news is, detecting melanoma early leads to significant treatment success. The five-year survival rate for localized melanoma is 99 percent.

Schedule Your Skin Cancer Screening in Buckeye and Scottsdale, AZ

Most moles are harmless, but the few that are cancerous can be life-threatening. The earlier a doctor diagnoses you with any form of skin cancer, the better your outlook will be. If you are worried about your mole, contact us to set an appointment with one of the best dermatologists in Buckeye and Scottsdale. We offer clinical excellence in skin cancer detection and treatment.