Melanomas can develop anywhere on your body. They most often develop in areas that have had exposure to the sun, such as your back, legs, arms and face. Melanomas can also occur in areas that don't receive much sun exposure, such as the soles of your feet, palms of your hands and fingernail beds. These hidden melanomas are more common in people with darker skin.
The first melanoma signs and symptoms often are:
- A change in an existing mole
- The development of a new pigmented or unusual-looking growth on your skin
Melanoma doesn't always begin as a mole. It can also occur on otherwise normal-appearing skin.
Normal moles are generally a uniform color, such as tan, brown or black, with a distinct border separating the mole from your surrounding skin. They're oval or round and usually smaller than 1/4 inch (about 6 millimeters) in diameter — the size of a pencil eraser.
Most people have between 10 and 45 moles. Many of these develop by age 40, although moles may change in appearance over time — some may even disappear with age.
Unusual moles that may indicate melanoma
To help you identify characteristics of unusual moles that may indicate melanomas or other skin cancers, think of the letters A-B-C-D-E:
- A is for asymmetrical shape. Look for moles with irregular shapes, such as two very different-looking halves.
- B is for irregular border. Look for moles with irregular, notched or scalloped borders — characteristics of melanomas.
- C is for changes in color. Look for growths that have many colors or an uneven distribution of color.
- D is for diameter. Look for new growth in a mole larger than 1/4 inch (about 6 millimeters).
- E is for evolving. Look for changes over time, such as a mole that grows in size or that changes color or shape. Moles may also evolve to develop new signs and symptoms, such as new itchiness or bleeding.
Other suspicious changes in a mole may include:
- Spreading of pigment from the mole into the surrounding skin
- Oozing or bleeding
Cancerous (malignant) moles vary greatly in appearance. Some may show all of the changes listed above, while others may have only one or two unusual characteristics.
Melanomas can also develop in areas of your body that have little or no exposure to the sun, such as the spaces between your toes and on your palms, soles, scalp or genitals. These are sometimes referred to as hidden melanomas, because they occur in places most people wouldn't think to check. When melanoma occurs in people with darker skin, it's more likely to occur in a hidden area.
Hidden melanomas include:
- Melanoma under a nail. Subungual melanoma is a rare form that occurs under a nail and can affect the hands or the feet. It's more common in blacks and in other people with darker skin pigment. The first indication of a subungual melanoma is usually a brown or black discoloration that's often mistaken for a bruise.
- Melanoma in the mouth, digestive tract, urinary tract or vagina. Mucosal melanoma develops in the mucous membrane that lines the nose, mouth, esophagus, anus, urinary tract and vagina. Mucosal melanomas are especially difficult to detect because they can easily be mistaken for other, far more common conditions.
- Melanoma in the eye. Eye melanoma, also called ocular melanoma, occurs in the uvea — the layer beneath the white of the eye (sclera). An eye melanoma may cause vision changes and may be diagnosed during an eye exam.
When to see a doctor
Make an appointment with your doctor if you notice any skin changes that seem unusual.
Jun. 12, 2012
- What you need to know about melanoma and other skin cancers. National Cancer Institute. http://www.cancer.gov/cancertopics/wyntk/skin. Accessed May 10, 2012.
- Abeloff MD, et al. Abeloff's Clinical Oncology. 4th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2008. http://www.mdconsult.com/das/book/body/208746819-4/0/1709/0.html. Accessed May 10, 2012.
- Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Edinburgh, U.K.; New York, N.Y.: Mosby Elsevier; 2010. http://www.mdconsult.com/books/about.do?about=true&eid=4-u1.0-B978-0-7234-3541-9..X0001-6--TOP&isbn=978-0-7234-3541-9&uniqId=230100505-57. Accessed May 7, 2012.
- Sureda N, et al. Conservative surgical management of subungual (matrix derived) melanoma: Report of seven cases and literature review. British Journal of Dermatology. 2011;165:852.
- Seetharamu N, et al. Mucosal melanomas: A case-based review of the literature. The Oncologist. 2010;15:772.
- Intraocular (eye) melanoma treatment (PDQ). National Cancer Institute. http://www.cancer.gov/cancertopics/pdq/treatment/intraocularmelanoma/patient/. Accessed May 15, 2012.
- Smith RA, et al. Cancer screening in the United States, 2012: A review of current American Cancer Society guidelines and current issues in cancer screening. CA A Cancer Journal for Clinicians. 2012;62:129.
- Skin examinations. SkinCancerNet. http://www.skincarephysicians.com/skincancernet/skin_examinations.html. Accessed May 10, 2012.
- Preventive services for adults. Bloomington, Minn.: Institute for Clinical Systems Improvement. http://www.icsi.org/guidelines_and_more/gl_os_prot/preventive_health_maintenance/preventive_services_for_adults/preventive_services_for_adults__11.html. Accessed May 15, 2012.
- Zelboraf (prescribing information). South San Francisco, Calif.: Genentech Inc.; 2011. http://www.zelboraf.com/dermatology/index.html. Accessed May 11, 2012.
- U.S. Preventive Services Task Force. Screening for skin cancer: U.S. Preventive Services Task Force Recommendation statement. Annals of Internal Medicine. 2009;150:188.
- Melanoma. Fort Washington, Pa.: National Comprehensive Cancer Network. http://www.nccn.org/professionals/physician_gls/f_guidelines.asp. Accessed May 10, 2012.
- Melanoma treatment. National Cancer Institute. http://www.cancer.gov/cancertopics/pdq/treatment/melanoma/healthprofessional/. Accessed May 10, 2012.
- Finn L, et al. Therapy for metastatic melanoma: The past, present and future. BMC Medicine. 2012;10:23.
- Reed KB, et al. Increasing incidence of melanoma among young adults: An epidemiological study in Olmsted County, Minnesota. Mayo Clinic Proceedings. 2012;87:328.
- Gibson LE (expert opinion). Mayo Clinic, Rochester, Minn. May 17, 2012.