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New moles: What causes the sudden appearance of moles?

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Have you ever noticed a new mole appear on your skin unexpectedly? While most moles are harmless, the sudden appearance of a new mole can sometimes be a cause for concern

It's important to understand what causes them and how to monitor them for potential skin cancer, so read on to learn more. 

How does a new mole suddenly appear?

A new mole appears when pigment-producing cells in the skin, called melanocytes, duplicate. This then causes moles on the surface of the skin. 

The scientific name for them is nevus. This comes from the Latin word for birthmarks. There is not much known about why we have moles on our bodies, but they are common. 

Moles can appear almost anywhere on the body - scalp, arms, legs, back, chest, even on areas you wouldn't expect such as between the fingers and toes, on palms and the soles of the feet, or under fingernails and toenails. 

What causes a new mole to appear on the body?

There is no definitive answer as to why moles suddenly appear in adults. A lot of research has been conducted into melanoma, but because most moles are nothing to worry about, they have not been studied as extensively. 

What we do know is that most new moles that appear later in life are often benign and likely occur because of age, certain medications, sun damage and genetic mutations.

6 Reasons behind the appearance of new moles

Checking a mole on back

1. Genetics and family history

Genetic mutations may play a large part in new moles appearing. It’s thought to be an interaction of genetic factors and sun damage. However, how exactly this causes moles is still not very well understood by researchers. 

One type of mole called atypical, or dysplastic nevi, is usually hereditary. They closely resemble skin cancers and individuals who develop them have a higher risk of developing malignant melanoma. 

2. Sun exposure

The development of new moles can also be caused by frequent sun exposure or sunburn. Protect yourself by wearing sunscreen every day and avoid using tanning beds, which can potentially increase the risk of moles. 

3. Skin type

People with light or fair hair and skin are more likely to have existing moles and develop new moles in adulthood. 

4. Hormonal changes

New moles can sometimes emerge as our bodies undergo changes. One example is during adolescence, as young bodies grow. They can also begin to show up during pregnancy and menopause as hormone levels fluctuate. 

5. Certain medical conditions and medications

A suppressed immune system from the body responding to the use of certain drugs, even antibiotics, can cause new moles to develop. Although they don't lead to a suppressed immune system, some skin conditions such as eczema can cause immune cells in the skin to become sensitive. 

6. Age

The older we are, the more exposure we have had to the sun over the years. This exposure is associated with new moles; therefore, the older a patient, the more likely moles are to develop. 

What causes a lot of moles to suddenly appear?

Eruptive nevi is a condition in which a lot of moles suddenly appear on the body. Cases are extremely rare and generally, it is caused by other things such as changes in hormones, medications or immune reactions to things like eczema. 

4 Tips to keep an eye on new moles on your body

Moles can appear on their own or in groups. They are typically evenly coloured brown spots but may also take different shapes or colours. Features of moles can include:

  • Colour: Moles can be brown, tan, red, pink, black or blue. 
  • Texture: Smooth or raised. They can also be flat, wrinkled or have hairs growing from them. 
  • Shape: Moles are most often round or oval.
  • Size: They are usually about 6 millimetres in diameter (the size of a pencil eraser). However, congenital nevi can be larger and cover part of a limb or the face.  

1. Use ABCDEs of melanoma to recognise cancer warning signs 

Learning how to identify melanoma and skin cancer is important for early detection. An easy way to remember how to check your skin is to use the ABCDE technique to identify changes.  

  • Asymmetry - Each half of the mole is a different shape
  • Border - Look for spreading or irregular edges
  • Colour - A recent change or blotchy spots with many colours
  • Diameter - spots are getting bigger 
  • Evolving - Changing or growing in size, shape or thickness 

2. Check your skin on a routine basis

Regular self-examinations of your skin will help you detect a difference in a mole over time.

However, moles and skin growths that appear on an adult should always be checked by a doctor. It’s recommended that people have yearly appointments with a skin cancer doctor for skin checks. But if you’re at risk for melanoma, your doctor may recommend a skin check every six months.  

3. Document and track changes in moles over time

As a part of your skin cancer self-examinations, you should also track the changes you notice.

Nowadays, there are many smartphone apps that can help you keep a record of changes in existing moles or when new ones appear. They allow you to take a high-resolution picture of your body to track any changes yourself, and some will even forward the image to your doctor for assessment. 

4. See a skin doctor for a professional mole check

When an old mole shows any of the above cancer warning characteristics, or a new mole appears in adulthood, you should have a consultation with a doctor to make sure it's not cancerous. If it looks suspicious, is bleeding, oozing or causing pain, it's important to seek an expert opinion for treatment options as soon as possible. With melanoma, the survival rate is higher for people who receive an early diagnosis. 

Moles can sometimes develop into melanomas, the deadliest type of skin cancer. But what you think is a new mole could also be a basal cell or squamous cell carcinoma, or absolutely nothing at all. If your doctor is concerned, they will normally take a biopsy to determine if a mole is benign or skin cancer.  

How to prevent moles from suddenly appearing on your body

The number of moles a person has is mainly caused by the genes you inherit. But protecting yourself from harmful UV rays, especially in childhood, can help avoid developing new moles as an adult. When it comes to prevention, you need to start by wearing proper sun protection every day and avoid using tanning beds altogether. 

Should I have a non-cancerous mole removed?

You can have a mole removed for cosmetic reasons or if it bothers you when you shave, for example. However, the routine removal of moles is not usually recommended. This is because moles are usually benign and mole removal is not recommended as a way to prevent melanoma. 

Some melanomas do develop from moles, but most don't. Routine skin examinations are a far better way to deal with the skin cancer risk that moles on your body bring.

When moles suddenly appear, you should keep a close eye on them for skin cancer symptoms. Better yet, schedule a mole check appointment with a skin cancer doctor who can give you more information about the health of your skin and your lifetime risk of developing melanoma. 

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