What is Melanoma Skin Cancer?
What is Melanoma Skin Cancer? Melanoma is a cancer that starts as a certain type of skin cell. To understand melanoma, it helps to know a little about the skin. Normal Skin is the largest organ in the body. It does many different things. It covers and protects the organs inside the body, helps to keep out germs, helps keep in water and other fluids, helps control body temperature, sends messages to the brain about heat, cold, touch and pain.
The skin has 3 layers. Form the outside in, they are epidermis, dermis, subcutis. The top layer of skin, the epidermis, is very thin and protects the deeper layers of skin and the organs, The epidermis itself has 3 layers. The bottom layer is made up of basal cells. These basal cells divide from keratinocytes, which make a protein called keratin. This protein helps the skin protect the body. The outermost part of the epidermis is called the stratum corneum, or horny layer. It is made of dead keratinoycytes that are shed as new ones form. The cells in this layer are called squamous cells.
Another type of cell, the melanocyte, is also foundint he epidermis. These cells make the brown pigment called malanin. Melanin makes skin tan or brown and protects the deeper layers of the skin from some of the harmful effects of the sun. Melanocytes are the cells that can become melanoma.
A layer called the basement membrane separates the epidermis from the deeper layers of skin. The basement membrane is important because when a cancer becomes more advanced it grows through this barrier.
Melanoma skin cancers:
Melanoma is a cancer that begins in the melanocytes. Because most of these cells still make melanin, melanoma tumors are often brown or black. But this is not always the case, the melanomas can also hve no color. Melanoma most often starts on the trunk (chest or back) in men and the legs of women, but it can start in other places, too. Having dark skin lowers the risk of melanoma. But it does not mean that a person with dark skin will never get melanoma.
Other skin cancers:
Skin cancers that are not melanoma are sometimes grouped together as non-melanoma skin cancers because they start in skin cells other than mlanocytes. These cancers include basal and squamous cell cancers. They are much more common than melanoma. Because they rarely spread, basal cell and squamous cell skin cancers are less worrisome and are treated differently than melanoma.
Skin tumors that are not cancerous:
Most skin tumors are not cancer (they are benign). These rarely, if ever, turn into cancer.
Some of them include:
Seborrheic keratoses - tan, brown, or black raised spots with "waxy" texture, or rough surface
Hemangiomas - benign blood vessel growths often called strawberry spots or port wine stains.
Lipomas - soft growths of benign fat cells
Warts - rough-surfaced growths caused by a virus
Moles (also called nevi) - benign skin tumors that start from melanocytes
Spitz nevus - a kind of skin tumor that somethimes looks a lot like melanoma
Last revised: 3/29/2010 www.cancer.org