About melanoma

What is the skin?

The skin is the outer covering of your body. It protects your body from injury and infection. It also helps to control your body temperature and get rid of waste matter through your sweat glands. The skin has two main layers: the outer layer (epidermis) and the inner or deeper layer (dermis).

The outer layer has three types of cells. The first are flat, scaly cells called squamous cells. Below the squamous cells are rounder cells called basal cells. The cells that give skin its colour (make melanin) are in between the basal cells. These cells are called melanocytes.

The deepest layer called the dermis has blood and lymph vessels, hair roots and sweat glands.

In rare cases, melanoma may develop in other parts of your body. For example, your eye, mouth, under your finger nails or toe nails. Melanoma happens when the cells do not behave as normal and keep growing when there is no need. This group of abnormal cells can form a lump or tumour.

What is melanoma?

Melanoma is a cancer of the cells that make melanin, the melanocytes. Melanin is the pigment that gives your skin its colour. Melanoma is the most serious type of skin cancer.

Melanoma happens when the cells do not behave as normal and keep growing when there is no need. This group of abnormal cells can form a lump ot tumour.

The cell changes usually start in the surface of the skin, either in a mole or in normal skin. In rare cases, melanoma may develop in other parts of the body, for example, in your eye, mouth, under your finger nails or toe nails, or in your bowel.

Types of melanoma

There are several types of melanoma and often they refer to where they grow in the body.

  • Superficial spreading melanoma is the most common type. It grows along the surface of your skin, often on the legs or chest and back. It may grow out of a mole that has suddenly changed.
     
  • Nodular melanoma is the second most common type and more common in men. It grows quite quickly down into the deeper skin layers. It may occur in normal skin that is not exposed to the sun very often. It has a raised area on the skin and may be brown or black in colour.
     
  • Lentigo melanoma is usually found in older people and often on your feet and toenails. It begins as a small, brown freckle or stain and gradually spreads to form a bumpy surface. It can grow slowly over many years.
     
  • Acral melanoma is usually found in the palms of the hands, soles of the feet or around the toenails. It is more common in dark-skinned people.
     
  • Melanoma of the eye is a rare melanoma of the eye. It develops in the lining of the eyeball called the uvea.Your doctor might call it uveal melanoma.

How common is melanoma?

Melanoma is one of the most common cancers both in Ireland and worldwide. It is increasing faster than any other cancer and it is rising rapidly in Ireland. More than 1,000 cases of melanoma are diagnosed each year in Ireland. This number is likely to increase in future years.

Read next: Symptoms and diagnosis of melanoma.

Date Last Reviewed: 
Monday, April 30, 2018