As you spend more time outside in the warm summer months or away on holiday for a few days, it's important to protect your skin from potential skin cancer and damage. And while slathering on the SPF [1] and wearing protective clothing are great preventative measures, it's also important to keep an eye on your skin year-round — especially your moles.

Most people may know the warning signs for skin cancer [2]: basal cell carcinomas often look like open sores, red patches, pink growths, or shiny bumps or scars. Squamous cell carcinomas can also look like open sores or scaly red patches, elevated growths with a central depression, or warts. And melanoma, the deadliest form of skin cancer, can be a variety of colours: black, brown, skin-coloured, pink, red, purple, blue, or white.

If you notice any new spots on your body or any change in existing moles, it's important to visit your dermatologist ASAP to get it checked out. But what about moles that don't look like the others on your body but aren't quite skin cancer? These are called atypical moles, and they can lead to skin cancer if you're not careful.

What is an Atypical Mole?

When you visit your dermatologist for a skin check, he or she will examine the moles on your body and may choose to biopsy ones that appear different from others. If skin cancer is ruled out, it may be an atypical mole.

"An atypical mole, also called dysplastic nevi, generally appear irregular clinically," board-certified dermatologist Sejal Shah, MD, founder of SmarterSkin Dermatology [3], tells POPSUGAR. When biopsied, your doctor will look at the mole under a microscope and determine whether the mole is atypical or not. These moles have cell abnormalities not seen in regular-appearing moles.

"Having atypical moles increases the risk of melanoma," she said. That sounds scary, but you can catch them early enough if you know the signs of an atypical mole.

What Are the Signs?

Atypical moles fit the ABCDE criteria of moles, explains dermatologist Kenneth Mark, MD:

• A: Asymmetry. The mole doesn't look the same on each side.
• B: Border. If the mole has an irregular border (i.e. not round all the way around), it's atypical
• C: Colour. If it's very dark or has multiple colours, this could be a sign for concern.
• D: Diameter. If it's larger than the size of a pencil eraser, about ¼ an inch or six millimeters, get it examined.
• E: Evolving. If the mole has changed over time, you should get it checked out.

Be sure to visit your dermatologist at least once a year for a yearly, thorough skin examination and check your own skin at least once a month. You should visit your doctor more if you have had skin cancer before, have reduced immunity, or a strong family history of skin cancer.

What Are the Different Types?

After your doctor examines the mole under a microscope, he or she will determine the severity of the mole and categorize it as: mild, moderate, or severe.

If it's mild, it only needs to be monitored clinically, explained dermatologist Dendy Engelman, MD. If it's moderately atypical, your doctor will decide whether or not you need to have it removed. Severely atypical moles need to be excised, she said.

So What Should I Do if I Have an Atypical Mole?

If you notice something on your body that fits into the ABCDEs of mole detection, visit your dermatologist ASAP. He or she will examine your moles closely and determine the best course of treatment; this may require having the mole removed entirely. If a moderate or severely atypical mole is moderate or severe and isn't removed, there's a chance it could turn into melanoma [4].

Keeping an eye on your moles and regularly checking your skin is key. When you go out in the sun, make sure you practice safe sun exposure: apply SPF 15-30 every day, and if you're planning on spending extended time outdoors, use at least broad spectrum SPF 30. Apply thoroughly and reapply every two hours, or every time you get out of a body of water.

Also, seek shade whenever possible and wear protective clothing [5], especially a hat with at least a two to three-inch brim that goes all the way around. Be sure to wear sunglasses that block UV rays to protect your eyes and the delicate skin around them.