How do moles and birthmarks occur?

Retired American supermodel Cindy Crawford’s mole above her lip is her trademark feature. — AFP

I have a mole on my face. You could say it has been one of my defining features. In the past few months, I have seen it grow larger. What is a mole actually?

A mole is a common skin growth.

They usually appear as small, dark brown or blackish spots on your skin.

They are caused by clusters of pigmented cells called melanocytes.

Melanocytes are the type of cells that produce melanin, the pigment that gives your skin your colour.

Moles are also called “nevi” in the medical world.

About melanocytes, does that mean that African races have more melanocytes than, say, a white race?

People who have darker skin do not necessarily have more melanocytes than people with lighter skin.

But they do have more active melanocytes, and their melanosomes may certainly be larger.

A melanocyte, which is a pigment cell, has organelles that contain the pigment melanin.

These pigment-containing organelles are called melanosomes.

Darker-skinned people have larger and more numerous melanosomes in their melanocytes, compared to lighter-skinned individuals.

The pigmentation of your skin is a complex process that involves your body’s keratinocytes as well.

Keratinocytes are the most abundant type of cells in your epidermis, the outermost layer of your skin.

Your melanocytes produce, store and release melanin.

Your keratinocytes receive melanin.

OK, that is interesting. I never knew that. So, is it common to have moles? I have a cousin who has several moles all over his body.

Yes, it is common.

Moles can appear during childhood and your teenage years.

You will be surprised to know that most people have about 10 to 40 moles on their body.

Some of them may change over time, and even fade away.

Many moles develop by the time you turn 50.

I have a pear-shaped birthmark on my butt. Is a birthmark the same as a mole?

A birthmark is an obvious concentration of colouration of your skin that you are born with.

Sometimes, people call these birthmarks “beauty marks”.

Birthmarks are usually flat and located on the surface of your skin, but some can be raised above your skin and/or extend into the tissues under it.

They can have different colours, e.g. brown, tan, black, light blue, pink, white, red, or even purple.

They are harmless.

How big can moles grow to be?

Moles are usually less than 6mm in diameter.

It is observed, however, that some moles present at birth can be much larger. These are called congenital naevi.

Moles can be brown, tan, black, red, blue or pink, but most tend to be brown.

They can be smooth, wrinkled, flat on your skin surface, or raised above your skin.

Most of them are oval or round.

They may sometimes have hair growing from them.

They can develop anywhere on your body, including on your scalp, between your fingers or toes, and even under your nails!

During adolescence or pregnancy, the hormonal surges that occur can cause them to become thicker and larger.

Are moles as harmless as birthmarks?

Most of them are harmless, but rarely, they may become cancer.

You need to monitor your moles.

If any of them looks unusual, or if they grow larger or change in shape, you must go see a dermatologist immediately.

Oh. I have a mole that I believe has grown larger. Is that skin cancer? I am scared!

Rarely, moles can turn into melanomas, which is a type of skin cancer.

There is an ABC guide you can use to determine whether or not your mole has possibly turned into a melanoma.

  • Asymmetrical shape – one half of your mole looks different from the other half.
  • Border – it has irregular, notched or scalloped borders.
  • Colour – it has changed colour, is multi-coloured or has uneven colour.
  • Diameter – it has grown beyond 6mm.
  • Evolving – it has changed in size, shape, colour or height, especially if part or all of it turns black.

Moles may also become itchy or start to bleed.

Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health, computers and entertainment. For further information, email The information provided is for educational and communication purposes only, and it should not be construed as personal medical advice. Neither The Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. The Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.

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