Skin cancer is a malignant growth on the skin which can have many causes. Skin cancer generally develops in the epidermis (the outermost layer of skin), so a tumour is usually clearly visible. This makes most skin cancers detectable in the early stages. Skin cancer begins in your skin's top layer — the epidermis. The epidermis is as thin as a pencil line, and it provides a protective layer of skin cells that your body continually sheds. The epidermis contains three main types of cells: squamous cells, basal cells and melanocyte.
Normally, skin cells within the epidermis develop in a controlled and orderly way. In general, healthy new cells push older cells toward the skin's surface, where they die and eventually are sloughed off. This process is controlled by DNA — the genetic material that contains the instructions for every chemical and biological process in your body. Skin cancer occurs when this process malfunctions. When DNA is damaged, changes occur in the instructions, which can cause new cells to grow out of control and form a mass of cancer cells
Symptoms
Skin cancer develops primarily on areas of sun-exposed skin, including the scalp, face, lips, ears, neck, chest, arms and hands, and on the legs in women. But it can also form on areas that rarely see the light of day — your palms, beneath your fingernails, the spaces between your toes or under your toenails, and your genital area.
A cancerous skin lesion can appear suddenly or develop slowly. Its appearance depends on the type of cancer.
What causes skin cancer?
The incidence of skin cancer is associated with various factors. These include having fair skin, a history of sunburn, and a history of excessive sun exposure, a tendency to develop moles on your skin, a family history of skin cancer, a personal history of skin cancer, and a weakened immune system.