What Is A Skin Mole?


A mole is medically referred to as Nevus (plural: Nevi). They are common, small, tinted spots on the skin. They can be raised, bumpy, smooth, and are usually nothing to worry about. Most people have them, and they can appear throughout childhood and adolescence. Equally, some can appear at birth. Changes to moles can be a sign of serious health issues and will be discussed in more detail below.

Types of skin moles

How a skin mole appears suggests a lot about its nature. The categorisation of skin moles enables you to determine if the mole is of concern or not. This can be via design, time acquired, and location.


A common mole is a growth on the body that cultivates when the tinted cells, or melanocytes, settle in collective groups. The darker your natural skin usually means the darker the appearance of your moles.

Atypical (Dysplastic nevi)

A dysplastic mole, commonly known as an atypical mole, is a mole that appears distorted. This distortion can appear through the moles' border, colour, surface or size. Typically, these characteristics would need to be investigated under a microscope, due to an increased risk of melanoma.

Moles can then be temporally classified into specific categories:


Congenital moles are caused by an overgrowth of pigment in the skin cells at birth. These are also classed into the bracket of birthmarks. They have the tendency to change during puberty and grow with the individual but only need to be treated if there is a suspected risk of skin cancer.


These are the large group of moles that appear throughout your life (post birth). Repeated sun exposure can encourage mole growth and are very common. Importantly, they are generally harmless.  

Moles can then further be classified by their location:

Junctional melanocytic nevi

This is an acquired mole that typically presents in sun-exposed areas of the skin. Normally light to dark brown, they develop where the epidermis (outermost layer of skin) and dermis (skin) meet.

Intradermal nevi

This is an acquired mole that is often softer in colour, due to the mole’s location. It Is positioned deep within the dermis (or skin), as opposed to being at the dermo-epidermal junction.

Compound nevi

This mole mirrors characteristics of both the junctional and intradermal moles, due to being located within both the dermo-epidermal junction and the dermis. These are commonly raised and tend to be less pigmented as they mature and fall deeper into the skin.


Halo nevi

This type of mole presents itself with depigmentation (or ‘halo’) around it. It's benign, meaning it is not harmful. It is unknown why, but the body selects one of the moles and starts to fight/destroy them, commonly connected to autoimmune processes (where your own immune system fights body tissue that is misinterpreted for a foreign material).

Causes of skin moles 

But what causes skin moles? Most moles are a collection of melanocytes that grow together instead of distributed on the skin. Melanocytes produce different types of melanin called eumelanin and pheomelanin in the epidermis. Simply put, these manufacture skin pigmentation. Each person will have a different amount due to an abundance of genetic and environmental factors. Environmental factors include age, UV light exposure, inflammation, and hormone levels.

Risks factors of skin moles

The main cause for concern in moles is the potential for melanoma to develop. This aggressive form of cancer is present in moles and can be the cause of the mole’s physical changes. Non-melanoma skin cancer is also a potential health risk. This is more common and less serious compared to its melanoma counterpart.

Research has reviewed the risk factors for skin cancers and grouped them into risk scores. Both genetic and non-genetic risk factors are apparent.4 A family history of skin cancer, your own history, or your age could induce a greater risk from your moles to your health.

Other risk factors include:

  • Sizable moles from birth
  • Abnormal moles
  • The number of moles you have correlates with the amount of risk you are under. 50+ moles indicates a considerably greater risk.

Management and treatment for skin moles

If your mole is an unchanged, common mole, then there is no need for further treatment. Simply keep an eye on it for any unusual developments. Melanoma UK gives an easy to remember actionable system for determining if the mole growth is concerning.

ABCDE rule:

  • Asymmetry: unequal moles
  • Border: uneven borders
  • Colour: multiple colours
  • Diameter: larger than 5mm
  • Elevation: getting progressively raised
  • Firm: firm moles
  • Growing: changing moles

If you see any of these warning signs, it is worth seeing a medical doctor. Some suggest 50-60% of cancers could be prevented or treated by early detection programs, hence early recognition is critical.4

Even so, if your mole has been identified as a troublesome mole, there are a few treatments associated with these developments.

Surgery to get the skin lesion removed is the primary treatment method. Non-surgical treatments include freezing (cryotherapy), anti-cancer creams, photodynamic therapy (PDT), radiotherapy and electrochemotherapy. A dermatologist, a plastic surgeon, a pathologist and/or an expert nurse may get involved if you have skin cancer.3 

Notably, some people develop skin lesions that are perfectly harmless but dislike the physical appearance of them. In this case, you may be able to get it removed. However, this may be a pricy expense as it poses no immediate physical detrimental effects on you that would support its removal.  


Can moles be prevented?

While there is a complex interplay between environmental and genetic factors that create the circumstance for a developing mole, there are some recommendations to negate potential risks of skin cancer associations. Primarily, UV light can increase the risk of cancerous moles. Hence, staying in the shade when the UV rays are at their strongest is recommended. If you have many moles, it is important to use strong sunscreen, wear clothes that cover your skin, and be aware of your family’s health history.

What are the complications of skin moles?

The main complications of skin moles include the development of serious conditions, like cancer. Unusual moles may indicate melanoma. In addition, you may be self-conscious about the appearance of any noticeable moles.

Are moles contagious?

No, moles are not contagious. It is a complex mix of genetic and environmental factors that cause these abnormal skin tags to present and can not be passed from person to person.

How common are moles?

Moles are extremely common. Although difficult to estimate the prevalence of moles, it is thought that most people have 10 to 40 moles.2

According to DermNet, about 1% of individuals are born with a congenital mole.1 Fair skin tends to have more. When a mole develops on an individual in early life, they tend to present continuously throughout life. 

When should I see a doctor?

Although most moles are harmless, there are some cases where they shouldn’t be ignored. For example, if a mole is bleeding, itchy, or appeared/changed in later life (30+).

It is important to seek medical advice if you are experiencing any of these issues. Although the worst-case scenario is rare, it is always better to be safe. If there is a problem, you will be referred to a specialist in a hospital setting for further tests.


Most moles are harmless. Of course, if a mole is new, looks a bit different to you, or is irritating you in any way, you should seek a medical professional. Long-term skin protection from UV rays, and being aware of your family history, is of the upmost importance in terms of preventing any detrimental mole developments.


  1. Moles (melanocytic naevi, pigmented nevi) | DermNet [Internet]. [cited 2023 Jul 20].
  2. Moles: Who gets and types [Internet]. [cited 2023 Jul 20].
  3. Non-melanoma skin cancer - Treatment. nhs.uk [Internet]. 2017 [cited 2023 Jul 20]. 
  4. Fontanillas P, Alipanahi B, Furlotte NA, Johnson M, Wilson CH, 23andMe Research Team, et al. Disease risk scores for skin cancers. Nat Commun. 2021; 12(1):160.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Edith Varley

Master of Nutrition – University of Leeds

Edith has a health-centred background, predominantly consisting of a bachelor’s degree in psychology and a master’s degree in nutrition. She is interested in global health, well-being, nutrition and medical sciences. She is currently managing data administration work for Humankind charity, alongside medical writing and editing.

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