*Links on this page will take you to content on the cancer.net website. Links will open in a new window.
About the skin
The skin is the body’s largest organ. It protects against infection and injury, and it helps regulate body temperature. The skin also stores water and fat and produces vitamin D.
Skin is made up of two main layers: the epidermis, which is the outer layer, and the dermis, which is the inner layer. The deepest layer of the epidermis, located just above the dermis, contains cells called melanocytes, which produce pigment or color.
Melanoma begins when normal melanocytes change and grow uncontrollably, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can spread to other parts of the body. A benign tumor means the tumor will not spread. Melanoma is always cancerous.
Sometimes, melanoma develops from a pre-existing mole. Melanoma occurs most commonly on the skin of men’s backs or on women’s legs, but melanoma can occur anywhere on the body, including the head and neck, the skin under the fingernails, genitals, and even the soles of the feet or palms of the hands. Melanoma may not have the color of a mole. It may have no color or be slightly red, called amelanocytic melanoma.
When found early, melanoma can often be cured with surgery. However, melanoma is the most serious form of skin cancer and can grow deep into the skin, invading lymph and blood vessels. The median age at which people are diagnosed with melanoma is just above 50 years old. Still, melanoma occurs in young adults with greater frequency than many other types of cancer.
This section focuses on cutaneous melanoma, which is melanoma that develops on the skin. Melanoma can also develop in the mucous membranes that line the mouth, gastrointestinal tract, vagina, and other locations around the body. Melanoma may also develop in the eye. You can learn more about melanoma diagnosed in other parts of the body, such as melanoma of the eye, melanoma of the anus, and melanoma of the vagina, in these specific cancer type sections. For information on non-melanoma skin cancer, review the section on basal cell and squamous cell skin cancers.
Looking for More of an Overview?
If you would like additional introductory information, explore these related items. Please note these links take you to other sections on Cancer.Net:
- ASCO Answers Fact Sheet: Read a one-page fact sheet (available as a PDF) that offers an easy-to-print introduction to this type of cancer.
Download the latest version of Adobe Acrobat Reader
- Cancer.Net Patient Education Video: View a short video led by an ASCO expert in this type of cancer that provides basic information and areas of research.
- Medical Illustrations
- Risk Factors and Prevention
- Symptoms and Signs
- Treatment Options
- About Clinical Trials
- Latest Research
- Coping with Side Effects
- After Treatment
- Questions to Ask the Doctor
- Additional Resources
Oncology®. All rights reserved. www.cancer.net.