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 ABCDE:
- 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.
Other suspicious changes in a mole may include:
- 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. Acral lentiginous melanoma is a rare form of melanoma that can occur under a fingernail or toenail. It can also be found on the palms of the hands or the soles of the feet. It's more common in blacks and in other people with darker skin pigment.
- 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, most often 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.
April 15, 2014
- What you need to know about melanoma and other skin cancers. National Cancer Institute. http://www.cancer.gov/cancertopics/wyntk/skin. Accessed Nov. 6, 2013.
- Niederhuber JE, et al., eds. Abeloff's Clinical Oncology. 5th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2014. http://www.clinicalkey.com. Accessed Nov. 6, 2013.
- 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.clinicalkey.com. Accessed Nov. 6, 2013.
- Tafinlar (prescribing information). Research Triangle Park, N.C.: GlaxoSmithKline; 2013. http://www.tafinlar.com. Accessed Nov. 8, 2013.
- Yervoy (prescribing information). Princeton, N.J.: Bristol-Myers Squibb Company; 2013. http://www.yervoy.com. Accessed Nov. 8, 2013.
- Intraocular (eye) melanoma treatment (PDQ). National Cancer Institute. http://www.cancer.gov/cancertopics/pdq/treatment/intraocularmelanoma/patient. Accessed Nov. 6, 2013.
- Smith RA, et al. Cancer screening in the United States, 2013: A review of current American Cancer Society guidelines and current issues in cancer screening, and new guidance on cervical cancer screening and lung cancer screening. CA A Cancer Journal for Clinicians. 2013;63:87.
- Skin examinations. SkinCancerNet. http://www.skincarephysicians.com/skincancernet/skin_examinations.html. Accessed Nov. 6, 2013.
- Preventive services for adults. Bloomington, Minn.: Institute for Clinical Systems Improvement. https://www.icsi.org/guidelines__more/catalog_guidelines_and_more/catalog_guidelines/catalog_prevention__screening_guidelines/preventive_services_for_adults. Accessed Nov. 6, 2013.
- Zelboraf (prescribing information). South San Francisco, Calif.: Genentech Inc.; 2013. http://www.zelboraf.com. Accessed Nov. 8, 2013.
- 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 Nov. 6, 2013.
- Reed KB, et al. Increasing incidence of melanoma among young adults: An epidemiological study in Olmsted County, Minnesota. Mayo Clinic Proceedings. 2012;87:328.
- Golden AK. Decision Support System. Mayo Clinic, Rochester, Minn. Aug. 2, 2013.
- Gibson LE (expert opinion). Mayo Clinic, Rochester, Minn. Dec. 12, 2013.
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