what is melanoma?

Melanoma is the rarest, but most serious form of skin cancer. This is because it is more likely to spread than other types of skin cancer. There are about 6,000 new cases of melanoma in the UK every year.

Cancer occurs when normal body cells get out of control, multiply and spread. The cells clump together to form a cancerous (malignant) tumour.

The place where the melanoma first starts to grow is called the primary site.
It may also spread to other parts of the body. This is called secondary canceror metastasis. Many melanomas can be removed at the primary site before any spread has happened.

Melanoma starts in the melanin (dark pigment)-producing cells in the outer layer (epidermis) of the skin.

These pigment–producing cells are called melanocytes. They are found all over the skin that covers the body. They are also found inside the body, in the moist lining membranes of the mouth, nose and throat, and of the vulva, vagina and lower bowel (rectum). They are also found in the eye, middle ear and the covering of the brain and spine.

Though most malignant melanomas are on the outer skin, they can also grow on internal organs, the vulva or vagina, and inside the eye.

There are four main types of melanoma:

• superficial spreading melanoma
  This is the most common type (70%). It usually starts in a mole or beauty spot, and tends to spread outwards before it grows vertically down. The mole gets larger, its edges become more ragged, and its colours may vary.
  
  It can occur at any age. It is most common in people in who are in their late fifties.
  
  
• nodular melanoma
  Usually starts in skin that is exposed to the sun less often, such as the back and chest. It can appear quite quickly and will start to grow deeper into the skin if it is not removed. This type may start where a mole has not previously been. The melanoma is often dark brown or black, and feels raised on the skin. It may bleed.
  
  It can occur at any age. It is most common in people who are in their late sixties.
  
  
• Lentigo Maligna Melanoma (LMM)
  LMM is sometimes called Hutchinson’s melanotic freckle. It usually starts on skin that has had long and frequent sun exposure, such as the face. It starts as a new mole or brownish patch and spreads flat and outwards. (Lentigo Maligna Melanoma is not the same thing as solar or simple lentigo, sometimes called age or liver spots). Lentigo Maligna Melanoma is slow growing, but may eventually start to grow deeper, and then form a lump.
  
  It is most common in people over 50.
  
  
• Acral lentiginous melanoma
  is most commonly found on the palms of the hands and soles of the feet, or around the big toenail. It can grow under the nails of the hands and feet too.
  Although it is very rare, this is the type of melanoma that is most likely to occur in people with naturally dark or black skin.

  Melanoma in situ is the medical term to describe cells that have become cancerous, but are of a type that is not know to spread and cause secondary cancer. However, if melanoma in situ is left untreated for long enough, it can turn into the type of melanoma that does spread. Lentigo Maligna is a type of in situ melanoma.
  
  Sometimes the melanoma cells do not make melanin. This is called amelanotic melanoma and it is rare. The appearance on the skin is as a spot which is pink or red, rather than brown or black.
  
  We have more general information about what cancer is.