This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science
This page was updated on August 11, 2022.
Because many melanomas develop on the skin where they’re visible, there’s a good chance of detecting them early. Regular examination of the skin for new or unusual growths, or changes in existing moles, is critical. If you find anything suspicious, you should discuss it with your primary care physician, a dermatologist (skin doctor) or a health-care professional qualified to diagnose melanoma.
Most moles are harmless. A normal mole is generally colored evenly (brown, black or tan) and is smaller than 6 mm in diameter (about the size of a pencil eraser). They may be flat or raised and generally don’t change over time.
Melanoma accounts for about 1 percent of all skin cancers, but it’s responsible for most deaths from skin cancer, according to the American Cancer Society.
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The key to detecting melanoma early is to know what to look for and where to look for it. This isn’t always easy, as melanoma can be a master of disguise. It may look like an age spot, a bruise, a sore, a cyst, a scar or a dark line beneath your nail. You may not feel a melanoma, but there are times that it may itch, hurt or bleed.
The ABCDE method may help you determine whether an abnormal skin growth may be melanoma:
If the answer to any of these questions is yes, or even maybe, see a dermatologist for a proper evaluation. The only way to be sure whether a mole is melanoma is to visit a doctor.
Other melanoma warning signs may include:
Sometimes melanomas can be itchy. They may also bleed and ooze.
Melanoma can be painful and tender to the touch, but you can also have melanoma without feeling any pain or discomfort.
Ugly duckling moles aren’t always melanomas, but they are a red flag. Normal moles on the body tend to resemble one another, but melanomas don’t look like other moles. They stand out just like the ugly duckling in the classic fairy tale. Ugly duckling moles may be bigger, smaller, darker or lighter than nearby moles. Moles that aren’t surrounded by other moles are also sometimes thought of as ugly ducklings. Melanomas can be masters of disguise. They may resemble sores, age spots, bruises, cysts or dark spots. Some appear as a dark line through a nail.
More than 90 percent of melanomas are thought to be caused by ultraviolet (UV) exposure, according to the U.S. Centers for Disease Control and Prevention. Among the types of UV rays, the sun’s UVB rays in particular stimulate skin cells known as melanocytes to produce melanin. This may cause a sunburn or tan and increase your risk for developing cancer-causing mutations in the cell’s genetic material.
Melanoma may be found anywhere on the skin, but it’s most likely to develop on sun-exposed areas, namely the chest and back in men and the legs in women. The neck and face are also common sites for melanoma.
If you have a darker skin type, you may be more likely to develop melanoma on your hands, the soles of your feet or under your nails. This is known as acral lentiginous melanoma and isn’t caused by UV damage from the sun. It may differ in appearance from other types of melanoma.
Signs of acral lentiginous melanoma may include:
Melanoma may also develop in the eyes (intraocular melanoma), or in the mouth, genitals or anal area (mucosal melanoma).
The doctor will biopsy a mole if it looks suspicious, and the cells will be sent to a lab for analysis. If it’s melanoma, the patient may require surgery to remove the mole. If it has started to spread to other areas, chemotherapy and radiation, biologic and targeted therapies may also be recommended.