What are the signs and symptoms of melanoma?

About half of all melanomas start with a new, abnormal-looking mole in normal-looking skin. This usually looks like a dark area or a new mole that changes over weeks or months. Other melanomas develop from a mole that you already have.

It can be difficult to tell the difference between melanoma and a normal mole. The following checklist explains what to look for. It is called the ABCDE list.

Photographs are from the website of the National Cancer Institute (cancer.gov).

A – Asymmetry

Most melanomas are likely to be uneven or irregular in shape (asymmetrical). Ordinary moles are usually more even and both halves look mostly the same (symmetrical).

Melanoma with assymetric shape

Melanoma with asymmetrical shape

Normal mole with symmetrical shape

Normal mole with symmetrical shape

B – Border

The edges around a melanoma (border) are more likely to be uneven. Ordinary moles usually have a clear, smooth-edged border.

Melanoma with irregular border

Melanoma with irregular border

Normal mole with symmetrical shape

Normal mole with clear border

C – Colour

Melanomas are usually more than one colour. They may have different shades, such as brown mixed with a black, red, pink, white or a blue tint. Normal moles usually only have shades of brown. If you have red or fair hair and pale skin, the melanoma may just be red with no brown.

Melanoma with colour difference

Melanoma with a colour difference

Normal mole with no colour difference

Normal mole with no colour difference

D – Diameter (width)

Melanomas are usually more than 6mm wide. Normal moles are usually about the size of the blunt end of a pencil, or smaller.

If you have lots of large moles, some of them may be larger than 5mm in diameter. These are likely to have been there for years without changing. But it is recommended that people with lots of moles and large moles get them checked by a dermatologist. This is important if you have had changes to moles in the past.

Melanoma with a diameter change

Melanoma with a diameter change

Normal mole with no diameter change

Normal mole with no diameter change

E – Evolving (changing)

Look for changes in the size, shape or colour of a mole. The change in shape can include the area becoming raised or dome-shaped. Or if the mole is flat it may stay that way but become wider.

When to see a doctor

Visit your GP straight away if you have:

  • any of the ABCDE signs
  • any unusual marks on the skin that last for more than a few weeks
  • a mole that tingles or itches
  • a mole that develops a crust or bleeds
  • something growing under a nail or a new dark-coloured stripe along part of the nail.

A melanoma is normally obvious, as it will look different to any other moles. So it is important to ask your GP to check anything that looks different or unusual.

Checking your skin

A good time to check your skin is after a bath or shower. Make sure you have plenty of light. Use a full-length mirror and a small handheld mirror for areas that are hard to see. This will get easier with time, as you become more familiar with your skin and what your moles normally look like.

You can ask your partner, a family member or friend to look at your back, neck and parts of your skin that are hard to see. You could also take pictures of your moles so you can see if there are any changes over time. Checking for these signs is very important, as melanoma can usually be cured if it is found at an early stage.

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