Where do our moles come from? What are they for ?

You have always had a lot of moles and it has never worried you… But new brown spots continue to appear on your arms or on your back? Where exactly do they come from and do they have any particular use? Answers from Dr Georges Reuter, dermatologist-venerologist and vice-president of the National Union of Dermatologists-Venerologists (SNDV).

Moles , also known by the scientific name nevus , dot our skin and add a unique touch to our appearance . Unloved for a long time, they are now considered real fashion accessories, to the point that some people do not hesitate to get tattoos... But where do they come from exactly? Do they have any particular use? We take stock with Dr Georges Reuter, dermatologist-venerologist and vice-president of the National Union of Dermatologists-Venerologists (SNDV).

Reminder: what is a mole (nevus)?

Moles, or nevi, are small spots or more or less pigmented growths that almost all of us have.

Concretely, these are small clusters of cells which have not found their place: “moles appear when melanocytes, the pigment cells specialized in the production of melanin , group together randomly in clusters instead of disperse,” explains the dermatologist.

Depending on the type of cells involved, moles can be light brown, dark brown, black, or even flesh-colored . Some are completely flat and others are slightly raised . Their size can vary from single to double. And the expert clarified:

Moles are nothing more than small skin tumors, but they are mostly benign and harmless. They rarely develop into melanoma, but must still be checked if there is a change in size or color. Dr Georges Reuter, dermatologist-venerologist.

What is the difference from a skin tag or wart?

Moles, skin tags and warts are small skin lesions that have very distinct characteristics.

  • As noted above, moles are small brown or black, even fleshy, spots , most often flat or slightly raised.
  • Skin tags are small, soft , benign  growths of skin found on the eyelids and skin folds (in the neck, under the armpits, etc.). They are usually flesh-colored or lightly pigmented.
  • Finally, warts are small skin lesions caused by a viral infection: they occur when a virus manages to infiltrate our body through a small wound. “Viral warts most often appear on the hands and feet , sometimes on the face. They are different from seborrheic warts , rough, more or less pigmented growths that can appear anywhere,” emphasizes Dr. Reuter.

Good to know: what is the meaning of moles?

Moles can sometimes be interpreted as omens... At the risk of surprising you, the term "beauty" did not always stick to it. During Antiquity, moles were considered unsightly ... In the Middle Ages, they were even considered signs of the devil  ! It was the reign of the Sun King who restored their image, establishing hairpieces, or "flies", as sophisticated fashion accessories .

In Chinese astrology, certain moles are also considered indicators of character or personality traits  based on their location and shape. A mole between the eyes and eyebrows, for example, refers to a rebellious, free and creative spirit, while a mole on the chin is synonymous with prosperity. Other folk beliefs are that moles are marks left by past life events.

Regardless, it is important to note that these beliefs are subjective and have no scientific basis .

Beauty moles… What are they for?

“From a medical perspective, moles do not appear to have any specific function . That said, we must be cautious: scientific advances can always surprise us,” replies Dr. Reuter.

A priori, moles do not fulfill a physiological function, but their presence can sometimes be useful for early detection of certain health problems . “A large number of moles with a diameter greater than 1 cm constitute an increased risk factor for developing skin cancer ( melanoma ),” warns the expert. 

At what age do moles appear?

Most humans have at least one mole  on their body . “The opposite is quite exceptional,” assures Dr. Reuter. These moles can appear on any part of the body: the face, neck, back, stomach, arms, legs, pubis, scalp and even the penis. They can be present at birth or develop over time ... “  Some babies are born with moles  : congenital nevi (around 1% of births). But these pigment spots appear most often in childhood or adolescence  and continue to develop in adulthood, until the age of 35, or even 40,” underlines the expert. And to clarify: “It is not impossible for a mole to appear after the age of 40, but it is better to pay attention to it, it can indicate skin cancer.”

Origin: where do moles come from and why do I have more and more of them?

As you will have understood, moles are formed from pigment cells. Clusters of melanocytes  begin to develop in the skin of the embryo, from the embryonic phase , which explains why some babies are born with moles, says our expert.

But moles can also form later in life, under the influence of various factors…

  • Genetic factors  : People with a family history of moles are generally more likely to have them as well.
  • Exposure to the sun  : Exposure to ultraviolet (UV) rays from the sun is known to promote the development of moles. “Excessive UV exposure can stimulate the growth of melanocytes and thus increase the number of moles,” assures Dr. Reuter.
  • A history of sunburn  : Severe sunburns that occur during childhood can increase the risk of developing moles in adolescence.
  • Hormones  : hormonal changes could indeed influence the growth of moles. For example, pregnant women may notice an increase in moles (controversial concept).
  • The phototype , in other words the type and complexion of the skin: people with fair skin and freckles  seem to be more exposed to skin cancers.

Is it normal or dangerous to have new moles?

At the risk of repeating ourselves, moles are most often benign . However, it is essential to monitor your moles for any changes in size, texture or color that could indicate a risk of melanoma. Stick to the ABCDE rule:

  • A for asymmetry  : one half of your mole is asymmetrical compared to the other;
  • B for borders  : your mole has irregular edges identifiable to the naked eye;
  • C for color  : your mole changes color or has an unusual color;
  • D for diameter  : the size of your mole seems abnormally large (greater than 6 mm;
  • E for evolution  : the appearance, size or texture of your mole changes, or a new mole appears after the age of forty.

If you notice the slightest abnormality, consult your doctor who will refer you to a dermatologist for a thorough evaluation: a biopsy for ablation may be necessary to avoid skin cancer!

My moles are disappearing, is it possible?

Yes, certain moles can disappear naturally over the course of life, without really knowing why.  Not to mention that  physical trauma such as a blow or injury can tear or burn a mole.

Good to know: contrary to what we sometimes read, mechanical friction (when the skin rubs against other surfaces such as clothing or jewelry) and prolonged exposure to the sun cannot promote lightening or the disappearance of moles!