Brief overview
- What is a birthmark (nevus, neavus)? A circumscribed, benign change of the skin or mucous membrane, usually different in color from its surroundings and congenital or acquired. Size, shape, color and other appearance can vary considerably.
- Types of birthmarks: most common are birthmarks based on pigment cells (pigment nevi), e.g. age spots, café-au-lait spots. Moles of other origin include port-wine stains (originating from blood vessels) and adipose tissue nevi (originating from fat cells).
- What are moles? Sometimes a synonymous term for moles in general. However, strictly speaking, the term stands for pigmented moles (pigmented nevi).
- How do moles / birthmarks develop? The formation is based on the local multiplication (rarely reduction) of certain cells, e.g. pigment cells in pigmented nevi.
- Why do you get birthmarks / moles? Partly unknown. Hereditary, hormonal and other factors may be involved. Spider nevi occur more frequently in chronic liver disease, among other conditions.
- What happens when you scratch a mole? As with other open wounds, there is a risk of wound infection. Therefore, clean and disinfect the wound and protect it from contamination. If itching was the reason for scratching, then go to the doctor.
What are birthmarks (moles)?
“Birthmark” is the colloquial name for a nevus (nevus). This is a circumscribed, benign skin or (more rarely) mucous membrane change that usually stands out in color from its surroundings.
Birthmark or mole – the difference:
Sometimes the terms “mole” and “birthmark” are used interchangeably – without distinction. However, “mole” actually only stands for a pigmented birthmark (see below: pigmented nevi), for example a café-au-lait spot.
Variable appearance
The shape, size, color, and other appearance of nevi can vary considerably:
- There are both flat and more or less raised (protruding) moles or moles.
- For example, the surface may be smooth, rough or wart-like; a mole or mole with hair is also possible.
- Some moles are tiny, others as large as the head of a pin, a lens or a walnut – or even larger: there are nevi that extend over a larger area of the body (many centimeters in diameter).
- The shape of a nevus can be roundish, oval or very irregular.
Sometimes a birthmark (mole) is present in a baby from birth. Other birthmarks (moles) develop later in children or even in adulthood. At the same time, nevi are not always permanent – some moles can disappear spontaneously, for example the so-called spider nevi. An acquired pigment spot (mole) also sometimes disappears on its own.
Types of birthmarks
There are quite different types of birthmarks. Very often they originate from pigment cells of the skin. Doctors then speak of pigment nevi. There are also birthmarks that derive from other cells (such as fat cells).
Pigment nevi
Pigmented nevi (“moles”) are pigmented birthmarks. They originate from pigment-forming cells (mainly melanocytes). Physicians distinguish different subtypes of pigmented nevi, for example:
- Café-au-lait spot: light brown (“milk coffee brown”), non-raised pigment spot that can grow to several centimeters in size. Such a light mole is either congenital or develops in early childhood.
- Caerulean nevus: Also called “blue nevus” or “blue mole.” Is a non-malignant, roundish, blue-black nodule that can become the size of a lentil. Most commonly, this type of mole (mole) is found on the scalp and on the backs of the hands and feet.
- Halo nevus: Halo nevus is a “white mole,” which is a dark mole with a white (depigmented) border or halo.
- Congenital melanocytic nevus: circumscribed, brownish birthmark, which is already present at birth or in the first weeks of life (sometimes such nevi develop later = tardive congenital nevi). Particularly extensive nevi are called giant nevi (giant birthmarks).
- Nevus dysplasia syndrome (dysplastic nevus syndrome): In this case, numerous atypical moles form, especially on the trunk, and usually after puberty. They enlarge by the end of the decade of life and sometimes also in the 4th to 5th decade.
Other nevi
Moles that do not originate from pigment cells but from other cells include:
- Nevus verrucosus: Yellow-brownish, wart-like nevus that originates from the epidermis – the uppermost layer of the skin, which consists mainly of horny cells. Often, several such nevi are arranged in a strip (linear).
- Nevus flammeus (port-wine stain): Congenital, irregular, sharply demarcated birthmark originating from blood vessels. It is light to dark red or red-bluish. Shape and size can vary greatly. Often, such a red birthmark is found on the face or neck.
- Nevus anaemicus: Irregularly bordered, white birthmark, the starting point of which is also blood vessels. Such nevi are usually localized on the chest.
- Nevus araneus (spider or spider nevus): Spider-shaped birthmark that also originates from blood vessels. Fine, visibly dilated capillaries radiate from a central, pinhead-sized, red vascular nodule.
Differentiation of similar skin lesions
There are various skin manifestations that may resemble a birthmark, thus posing a risk of confusion. Here are some examples:
A “red mole” or “red mole” may actually be a “hemangioma” (medically infantile hemangioma). This is a benign vascular neoplasm that occurs in many babies.
Tardive hemangiomas also often form during pregnancy. After birth, these “red moles” may disappear again. Hormonal factors are therefore probably involved in their formation.
The distinction ‘birthmark or wart?’ is also not always easy. There are quite different types of warts, and some of them can look strikingly similar to a warty nevus. The same goes for senile warts (warts of old age), which are not really warts at all.
What should I do if I have scratched open a mole?
Have you scratched a birthmark or mole? The spot may even be bleeding? In general, there is no need to worry at first. It is important to clean, disinfect and protect a scratched mole from contamination, just as you do with other wounds. In this way, you can prevent the sore birthmark from becoming infected.
If this does happen or the wound does not heal properly, you should go to the doctor. If you scratched the birthmark because it itched, or if the birthmark bleeds on its own, you should always see a doctor (see below: When to see a doctor?).
The same recommendations (clean, disinfect, protect from dirt, possibly see a doctor) apply if you have scratched off protruding moles or liver spots.
Moles are formed by the proliferation (rarely reduction) of certain cells:
For example, locally accumulated melanocytes form a brownish to brown-black pigment nevus. Melanocytes produce the pigment melanin and thus provide the skin coloration. A fat nevus (nevus lipomatodes superficialis) is caused by locally accumulated fatty tissue in the skin. A port-wine stain (naevus flammeus) is caused by dilated superficial capillaries (finest blood vessels).
Why do you get birthmarks / moles?
Sometimes birthmarks exist from birth, such as port-wine stains and fatty tissue nevi. The cause of these congenital nevi is unknown. Hereditary and hormonal factors, among others, may be involved in their development.
Such factors may also play a role in acquired nevi. For example, many birthmarks (moles) occur in families, which suggests a hereditary predisposition. The fact that new moles often appear during puberty and pregnancy indicates the involvement of hormonal factors.
Spider nevi, for example, are often found in pregnant women as well as people undergoing estrogen therapy, but also in children. It is not uncommon for these spider-shaped “liver spots” to be caused by chronic liver disease such as cirrhosis.
In the meantime, it has been discovered that UV irradiation of the skin that does not cause sunburn also promotes pigmented birthmarks. This means that the decisive factor is how much UV radiation the child’s skin has received over time (cumulative UV dose). Light skin types proved to be particularly susceptible to moles.
Another possible influencing factor is the suppression of the body’s defenses (immunosuppression). If, for example, immune reactions are suppressed by medication after an organ transplant, pigmented moles may develop more frequently or existing nevi may change. The same can happen with chemotherapy in childhood or with HIV-related immunodeficiency.
Many development factors cannot be influenced, especially in the case of congenital birthmarks (moles). However, the development of new pigmented moles can often be prevented by protecting the skin from too much UV light.
Birthmark development from head to toe
While some types of birthmarks and moles are not very particular about where they appear, others prefer certain areas of the body or only appear in certain places:
Age-related lentigines (age spots), for example, appear only on sunlit areas of the skin. These include the face, the backs of the hands and the outside of the forearms. Port-wine stains form mainly on the face and neck. Equally common is a prominent red mole on the front of the neck.
Moles in the eye or mouth
Sometimes a birthmark / mole even appears in the eye. Relatively common is the so-called choroidal nevus. This is a pigmented or unpigmented birthmark in the eye that originates from the choroid – the innermost section of the middle eye skin. Often, the ophthalmologist discovers it only by chance during an examination. Choroidal nevi are usually benign.
Rarely, a mole / mole develops in the mouth, for example, a pigmented nevus (pigmented mole). Such dark moles are most common on the mucosa of the lips and cheeks and on the hard palate.
However, an oral birthmark can also be white as in the case of the white mucosal nevus (nevus spongiosus albus mucosae). This type of birthmark originates from the epithelium and appears as an accumulation of doughy white plaques in the oral cavity.
Moles in the genital area
Occasionally, nevi form in the genital region. For example, some girls and women have an often very dark mole in the labia area. A birthmark/moles on the penis or testicles can be just as noticeable.
Other zones in the intimate area that can be affected include the region around the anus and the nipples.
Birthmark (mole): When to see a doctor?
Moles are usually harmless: although they displace surrounding tissue, they do not destroy it or form metastases. This makes them benign skin tumors that generally do not require treatment from a medical point of view.
However, if those affected find their nevi cosmetically disturbing (e.g. a large mole or port-wine stain on the face or a dark mole on the lip), they should see a dermatologist. This person knows how to remove the benign skin tumor.
Under certain circumstances, a mole can also develop into skin cancer. This is an uncontrolled growing skin tumor that grows into surrounding tissue and destroys it. In addition, skin cancer can form metastases. Changes in the size, shape or color of moles, for example, can indicate such a degeneration.
- A mole (mole) becomes larger, grows irregularly or rapidly, respectively.
- The nevus changes its overall color or discolors irregularly.
- The hair on the mole falls out.
- The mole (mole) becomes crusted, i.e. a crust (suddenly) forms on the mole.
- You have a bleeding or itching mole.
- You have an inflamed mole or a mole with an inflammatory rim – recognizable by classic signs of inflammation: The mole (mole) is red (bordered), hurts, is swollen, and warm.
Also, if you suddenly get (many) new moles/moles, be sure to see a doctor!
Skin cancer screening
Some people are particularly susceptible to skin cancer, for example those with a fair skin type, frequent UV exposure or many sunburns in the past (especially in childhood). People who have a large number of moles or liver spots are also at risk. Regular screening by a doctor offers the chance to detect skin cancer at an early stage.
You can find out more about this “birthmark check” and possible coverage by health insurance here.
Detecting malignant moles
Even a layman can assess whether a harmless mole has developed into skin cancer (or is well on the way to becoming so) with the help of the ABCD rule. This involves assessing a mole with the naked eye in relation to four criteria, such as whether it has a symmetrical shape and sharp edges.
Also potentially suspicious is an inflamed mole (inflamed birthmark) or a skin mole that changes in some other way – for example, becomes larger or changes color.
You can learn more about what to look for in moles/moles in the article Detecting Malignant Moles.
Removing moles
Medical professionals can remove moles using a variety of methods. For example, they can cut out, laser or abrade nevi. It depends on the type and size of the birthmark, among other things, which method is best in each case.
You can find out more about the different ways of removing moles, how much it costs and whether home remedies also help in the article Removing moles.
