Anytime you spend time outdoors, sunscreen should be your best friend, whether you’re on the beach, in the park, or just walking outside. Prolonged exposure to the sun’s UV rays can do a great deal of damage to the skin. Approximately 9,500 people in the U.S. are diagnosed with skin cancer every day.

According to the Skin Cancer Foundation, melanoma develops when ultraviolet radiation from the sun or tanning beds triggers mutations that lead skin cells to multiply rapidly and form tumors. Complicating matters, melanomas often look like moles and can even develop from existing moles, but they have the potential to be far more dangerous. Although the majority of skin cancer cancers are non-melanoma, melanoma is the most dangerous form of skin cancer.

The American Cancer Society estimates 97,610 new melanomas will be diagnosed this year alone. Melanoma is much more likely to grow and spread to other parts of the body that can be more difficult to treat, and it is estimated that 7,990 deaths will be attributed to melanoma.

Learning the ABCDE signs of melanoma can help you to identify a malignant mole or melanoma and act quickly before it spreads. If you recognize one or more of the following on your skin, consult your physician as soon as possible:

A – Asymmetry: Benign moles are symmetrical, meaning that each half of the mole matches the other if you were to draw a line through them. If you notice a mole that doesn’t seem symmetrical, it’s a good idea to get it checked.

B – Borders: Benign moles have smooth, even borders, whereas early melanomas look uneven, with scalloped or notched edges.

C – Color: Most benign moles have a uniform color – usually a shade of brown. Moles with a variety of colors are warning signs. These can include different shades of brown, tan, or black. Melanomas can even be red, white, or blue.

D – Diameter: Melanomas are usually larger in diameter than their benign counterparts. The diameter of the eraser on your pencil (about a quarter of an inch) is a good gauge for size – usually, a malignant mole is larger.

E – Evolving: Unlike benign moles, melanomas tend to change shape, size, color, or elevation over time. Keep an eye out for moles that evolve in this manner or develop other symptoms such as bleeding, itching, or crusting.

In addition to moles, it’s important to check your skin for anything new, changing, or unusual. This can include:

• a skin growth that increases in size and appears transparent, pearly, brown, tan, black, or multicolored
• a sore or spot that itches, crusts, scabs, or bleeds
• any open sore that doesn’t heal within three weeks

If you notice any unusual skin changes, contact your primary care provider or dermatologist.

Now that you are literate in the ABCDEs of melanomas, you can monitor your skin for changes that may be concerning.

This article was reviewed by Dr. Jack Krushell, Atrius Health Chief of Dermatology.