What is melanoma skin cancer?

Melanoma is a type of skin cancer that occurs when melanocytes (the cells that give the skin its tan or brown color) begin to grow out of control.

 

Cancer occurs when cells in the body begin to grow uncontrollably. Cells from almost any part of the body can become cancer and can then spread to other areas of the body. For more information about cancer, how it originates and spreads, see What is cancer?

 

Melanoma is much less frequent than other types of skin cancers. But melanoma is more dangerous because it is much more likely to spread to other parts of the body if it is not discovered and treated early.

Most skin cancers start in the top layer of the skin cell pro, called the epidermis. There are three main types of cells in this layer:

 

Squamous cells - These are flat cells located in the most superficial (outer) part of the epidermis that are constantly shedding as new cells form in the deeper layers.

Basal cells: These cells are in the lower part of the epidermis, called the basal cell layer. These cells constantly divide to replace squamous cells that flake off the surface of the skin. As these cells move into the epidermis they become flatter, and over time they become squamous cells.

Melanocytes: These are the cells that can turn into melanoma. They normally produce the brown pigment called melanin, which makes the skin brown or tan. Melanin protects the deepest layers of the skin against the harmful effects of the sun.

The epidermis is separated from the deeper layers of the skin by the basement membrane. When skin cancer becomes more advanced, it usually breaks through this barrier and invades the deeper layers.

 

Melanoma skin cancers

Melanoma is a cancer that begins in melanocytes. This cancer is also known as a malignant melanoma and cutaneous melanoma. Most melanoma cells continue to produce melanin, so melanoma-like tumors are usually brown or black. However, some melanomas do not produce melanin and may appear pink, pale, or even white.

 

Melanomas can develop anywhere on the skin, but they are more frequent in the trunk (chest and back) of men and in the legs of women. The neck and face are other common sites.

 

Having dark pigmented skin lowers the risk of melanoma in these most common places, although anyone can also develop this type of cancer on the palms of the hands, the soles of the feet or under the nails. Melanomas in these areas are more common in black Americans than in white Americans.

 

Melanomas can also form in other parts of the body such as the eyes, mouth, genitals, and anal area, but they are much less common than melanomas of the skin.

 

Melanoma is much less frequent compared to other types of skin cancer. But melanoma is more dangerous because it grows faster and is much more likely to spread to other parts of the body if it is not discovered and treated early.

Other types of skin cancer

There are many other types of skin cancer. Nonmelanoma skin cancers are sometimes grouped as nonmelanoma type skin cancers because they develop from other skin cells and not from melanocytes. These tend to behave very differently from melanomas and are often treated with different methods.