Booklet: What You Need to Know about Melanoma

What Is Melanoma?

Melanoma is a type of skin cancer. It begins in certain cells in the skin called melanocytes. To understand melanoma, it is helpful to know about the skin and about melanocytes--what they do, how they grow, and what happens when they become cancerous.

The Skin

The skin is the body's largest organ. It protects us against heat, sunlight, injury, and infection. It helps regulate body temperature, stores water and fat, and produces vitamin D. The skin has two main layers: the outer epidermis and the inner dermis.

The epidermis is mostly made up of flat, scalelike cells called squamous cells. Round cells called basal cells lie under the squamous cells in the epidermis. The lower part of the epidermis also contains melanocytes.

The dermis contains blood vessels, lymphatic vessels, hair follicles, and glands. Some of these glands produce sweat, which helps regulate body temperature, and some produce sebum, an oily substance that helps keep the skin from drying out. Sweat and sebum reach the skin's surface through tiny openings called pores.

   << Back                          Back to Content Page                         Next>>