Skin cancer is one of the more common cancers with more than 2 million cases diagnosed each year in the U.S.  The good news is that many skin cancers can be prevented or detected early and treated effectively.  Skin cancers originate in the outer skin layer (epidermis) and are classified according to the types of cells involved.

There are 3 types of skin cancer:
  • Melanoma
  • Basal cell skin cancer
  • Squamous cell skin cancer
Melanoma is more aggressive than basal cell skin cancer or squamous cell skin cancer.  Melanoma is a disease in which malignant (cancer) cells form in the skin cells called melanocytes (cells that color the skin).

Melanocytes are found throughout the lower part of the epidermis. They make melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment, causing the skin to tan, or darken.

The skin is the body’s largest organ. It protects against heat, sunlight, injury, and infection. The skin has 2 main layers: the epidermis (upper or outer layer) and the dermis (lower or inner layer).

When melanoma starts in the skin, the disease is called cutaneous melanoma. Melanoma may also occur in the eye and is called intraocular or ocular melanoma.

Content from http://www.cancer.gov/cancertopics/pdq/treatment/melanoma/Patient/page1