Beauty spot or cancer?

Posted on 5 January 2017

Is that mark on your skin just a mole or could it be a melanoma? We take a closer look at this potentially dangerous form of cancer.

What is melanoma?

Melanoma is a type of cancer that develops in your skin’s pigment cells. Although it’s not the only form of skin cancer, it’s the most deadly. ‘Melanoma is potentially the most dangerous form of skin tumour, accounting for about 90% of skin cancer mortality,’ says Dr Tedros Amha, a specialist dermatologist at Mediclinic Tzaneen. ‘Worldwide there is an increasing trend in melanoma, especially among light-skinned people.’

What does it look like?
Most melanomas start out looking more or less like a freckle or an ordinary mole. How it develops from there depends on which kind it is. The two most common melanomas are:

Superficial spreading melanoma
These look like a beauty spot gone wrong and are less cause for concern. Typically they’re flat with an irregular border. Women tend to develop them on their legs, while men get them on their backs.

Nodular melanoma
These are the serious kind. They are elevated and usually somewhat domed. While superficial melanomas often grow on an existing mole, nodular melanomas appear previously unmarked skin.

Under the scope
‘Histology [microscopic analysis] is a specialist’s most important tool in determining a prognosis,’ says Dr Amha. When specialists biopsy a skin tumour, the key thing they’re looking for is the growth pattern – how the malignant cells are distributed.

Horizontal
If a melanoma is growing sideways – getting wider on the top surface of the skin with a depth of around 1mm – the prognosis is generally good.

Vertical
If a melanoma is growing downwards, deeper into the layers of the skin, the prognosis gets poorer the deeper the tumour penetrates. The reason why depth is so critical is because once a melanoma starts penetrating blood vessels, the potential for the spread of cancerous cells to other parts of the body increases exponentially.

When should I see a specialist?
If you’re not sure whether your skin blemish is just a mole or a life-threatening condition, Dr Amha recommends applying the ABCDE rule:

Asymmetry
If you could fold a melanoma in half, the two sides wouldn’t match up.
Border
Most moles have a smooth edge where they meet the rest of your skin, but a melanoma is most often irregular.
Colour
Moles are usually a shade of brown, but critically, they’re the same shade across the whole surface. By contrast, melanomas might have different tones or even change colour over time.
Diameter
When it comes to skin conditions, size matters. Anything over 6mm is cause for immediate concern.
Evolution
Moles are static and look more or less the same forever. A melanoma will evolve over time, and the more rapid the change, the more serious the problem. If you notice a change in size, colour, or shape, it’s worth having it looked at.

‘Some dermatologists also include an F,’ Dr Amha adds. ‘Basically, any new skin lesion that you haven’t seen before and looks ‘funny’ should be investigated.’

Words: David Beukes

Published in Dermatology

In the interest of our patients, in accordance with SA law and our commitment to expertise, Mediclinic cannot subscribe to the practice of online diagnosis. Please consult a medical professional for specific medical advice. If you have any major concerns, please see your doctor for an assessment. If you have any cause for concern, your GP will be able to direct you to the appropriate specialists.

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