Why do some moles darken or change shape or surface? What does it mean?

Moles are common pigmented skin growths that almost everyone has. They can be present from birth or develop during life, and most often form when melanocytes – the pigment-producing cells – cluster in certain areas of the skin. In most cases moles remain stable for years and cause no problems. Sometimes, however, people notice that a mole starts to change: it darkens, changes shape or surface, or even starts to itch or bleed. These changes often cause concern because they may be linked to more serious skin conditions, including melanoma – the most aggressive form of skin cancer. But not every changed mole means danger. In this article we explain which changes are natural and when you should be concerned and see a doctor.

WHY DOES A MOLE CHANGE COLOUR?

Changes in mole colour can be natural and physiological or a warning sign of possible disease.

In some cases darkening is completely normal. For example, hormonal changes during pregnancy or puberty can stimulate the production of melanin – the skin's natural pigment – making moles more intensely coloured. Similar changes can also occur with age: some moles may darken, while others may even fade.

However, sudden, noticeable or uneven darkening of a mole is a signal that needs attention. If a mole becomes multicoloured (e.g. a mix of brown, black, grey or even bluish shades) or develops contrasting areas, this may be a sign of melanoma. Such colour changes indicate possible mutation processes in which melanocytes multiply uncontrollably and behave abnormally.

It is important to monitor not only new moles but also old ones – if a mole that has been stable for a long time suddenly starts to darken, that is reason enough for a preventive visit to a dermatologist.

WHY DOES A MOLE CHANGE SHAPE?

Most healthy moles are symmetrical – round or oval with clear, regular edges. Sometimes, however, their shape starts to change – one edge grows, the outline becomes irregular or "blurred", like an unevenly painted spot.

Changes in shape can be linked to several factors. In childhood or adolescence moles can grow along with the body, so it is natural for their size to change. However, a sudden or uneven change in shape on adult skin is a sign that must be monitored. Another possible cause is irritation, when a mole is constantly rubbed, nicked while shaving, or pressed by clothing or backpack straps. Such mechanical factors can cause inflammation that changes the skin growth.

The most important rule: if a mole noticeably grows, loses its symmetry or seems to "spread outwards" within a short time (a few weeks or months), it must be assessed by a dermatologist.

WHY DOES THE SURFACE OF A MOLE CHANGE?

Healthy moles usually have a smooth, uniform surface and may be flat or slightly raised above the skin. In some cases moles may become rougher with age, but this happens slowly and often without other signs.

Worrying surface changes, however, appear faster and are more pronounced. Cases are considered dangerous when a mole:

• starts to peel or flake – this may indicate atrophy of surface skin cells or hyperkeratosis;
• develops crusts, sores or ulcers that heal poorly;
• bleeds, even when not touched – this may indicate inflammation or cell degeneration;
• suddenly becomes rough, hard or very raised – a possible benign growth or tumour process.

Such signs may indicate dysplastic moles or even the onset of melanoma. Early diagnosis makes it possible to prevent more serious consequences in time.

WHEN SHOULD YOU WORRY? THE ABCDE METHOD

Dermatologists around the world use the ABCDE system to help assess whether a mole may be dangerous:

If a mole meets at least one of these criteria, it is recommended to see a dermatologist or dermato-oncologist as soon as possible.

WHAT DO THESE CHANGES MEAN?

Changes in the appearance of a mole do not necessarily mean cancer. A common finding is so-called dysplastic moles – benign but unusual-looking moles with an uneven surface, irregular edges and mottled colours. Such growths can exist for years without any problems, but they carry a higher risk of turning into melanoma, especially with a genetic predisposition.

Another common diagnosis is seborrhoeic keratosis, which is often mistaken for a malignant mole. It is a benign, rough, brown or black spot that often appears with age.

The most dangerous possibility is melanoma, which can start either in a long-standing mole or in a newly appeared growth. Melanoma spreads quickly and often metastasises, so it is important not to ignore any changes in a mole.

WHEN TO SEE A DERMATOLOGIST

Even if a mole does not change, it is recommended to have a preventive skin check once a year, especially if you have many moles or family members who have had skin cancer. However, see a doctor immediately if:

• A mole is changing rapidly (within a few weeks or months).
• Pain, itching or bleeding appear.
• A new growth appears on the skin that looks different from the others.
• You have fair skin and have often been sunburned – the risk is higher.
• You are over 30 and new moles have started to appear.

Early diagnosis, even if the changes seem minor at first, can help prevent melanoma or cure it at an early stage.

CAN YOU USE COSMETICS ON OR AROUND MOLES?

Many people wonder whether facial care products can be used around moles. The answer depends on the condition of the mole. If the mole is stable, without sores or inflammation, cosmetics are usually safe, but they should not be rubbed in or scrubbed directly onto it.

Products with acids (e.g. AHA, BHA), retinoids or essential oils can cause irritation, especially if the mole is raised. You should also avoid applying brightening products with hydroquinone or other active ingredients to pigmented growths without medical advice.

If you are planning exfoliation or peeling treatments, it is best to leave a small safety margin around moles to reduce possible irritation or pigmentation changes.

To learn more about protecting your skin from the sun and reducing the risk of skin cancer, read “Skin cancer: how can you protect yourself?”.

SOURCES

1. American Academy of Dermatology (AAD)
2. Skin Cancer Foundation
3. Mayo Clinic – Moles and Melanoma
4. Journal of the American Academy of Dermatology
5. National Cancer Institute – Moles and Skin Cancer

# moles