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Melanoma

What is melanoma?

Melanoma, also called malignant melanoma, is a type of skin cancer. It starts in skin cells called melanocytes. These are the cells that make melanin, the pigment that gives skin its colour.

Melanoma often develops on skin that has been exposed to the sun. This is because ultraviolet (UV) radiation from sunlight or sunbeds can damage the DNA inside melanocytes. When this damage happens, the cells can grow out of control and form melanoma.

Types of melanoma

Melanoma can start in different parts of the body:

  • Cutaneous melanoma – starts on the skin (this is the most common type)
  • Mucosal melanoma – starts in moist areas of the body, such as the mouth or genitals

Superficial spreading melanoma

This is the most common type in the UK (about 60 to 70% of cases).

It usually grows slowly across the surface of the skin before it grows deeper. Once it grows deeper, it can spread to other parts of the body.

Signs to look for:

  • Uneven shape (not symmetrical)
  • Irregular edges
  • Different colours (brown, black, blue, grey, pink or red)
  • Usually larger than 6mm
  • Changes over time (weeks, months or years)

Nodular melanoma

This is the second most common type (about 15 to 20% of cases). It tends to grow quickly down into the skin. It often appears as a raised lump.

Signs to look for:

  • Larger than 6mm
  • Dome-shaped lump
  • One colour (often black, red or skin-coloured)
  • Surface may be smooth, rough or crusty
  • May bleed or ooze
  • Can feel itchy or sore

Lentigo maligna melanoma

This type is more common in older people who have had a lot of sun exposure over many years.

It usually develops slowly on sun-exposed skin.

Signs to look for:

  • Flat or slightly raised patch
  • Brown in colour
  • Irregular edges
  • Grows slowly over several years
  • Similar features to superficial spreading melanoma

Acral lentiginous melanoma

This is a rarer type of melanoma. It appears on the palms of the hands, soles of the feet, or under the nails. It is often found later because it can be harder to spot. It is more common in people with darker skin.

Signs to look for:

  • Dark patch (brown, blue or black)
  • Can become a lump or sore later
  • May itch
  • Often larger than 7mm
  • Colour spreading from under a nailbed

Further information

At The Christie, the melanoma team treat patients with melanoma.

Last updated: June 2026