Melanoma, the deadliest of skin cancers, has increased 27% in the last decade. While melanoma accounts for about 1% of all skin cancers, it causes a large number of skin cancer deaths, according to the American Cancer Society.

Melanoma strikes approximately 100,640 Americans annually, and about 8,290 people are expected to die from it, with almost twice as many men as women succumbing to the disease.

Older adults who have experienced decades of skin exposure are particularly vulnerable to this potentially deadly disease. But if caught early, melanoma is highly curable, according to AARP.

About 90% of nonmelanoma cancers and 85% of melanoma cases are associated with exposure to ultraviolet (UV) radiation from the sun, so avoiding sun exposure as much as possible and being sun-smart is your first step in prevention. And being vigilant about checking your skin for any changes is another. The American Cancer Society offers guidance on how to do a monthly skin self-exam.

“Melanoma is a rule breaker,” says Dr. Elizabeth Buchbinder, an oncologist at the Dana-Farber Cancer Institute in Boston. Little moles can cause big trouble, and new spots can grow and spread quickly, she says. “And so, knowing what to look for is super important.”

Here are four warning signs to watch for:

1. The “ugly duckling.” Buchbinder says that people who have a lot of moles are at increased risk for melanoma but there’s no need to panic. “If you have a bunch of dark moles, but you have 50 of them, they’re not all melanomas,” she says. “But if you have one mole that really looks different, and it’s kind of the ugly duckling, that’s the one that you should really want to get looked at and checked.”

2. “Where the sun doesn’t shine.” Although most melanomas are caused by UV light, some aren’t. Check the soles of your feet and palms of your hands for dark streaks that could be a sign of melanoma.  Musician Bob Marley thought the mark under his toenail was caused by a bruise, and eventually died from melanoma. Buchbinder says she has also seen rare cases of melanoma develop on the eye, inside the mouth or on the scalp. According to AARP, these hidden melanomas are more apt to strike people with darker skin.

3. Red, white, and blue hues. Not all melanomas are dark-brown moles. Dr. Robert Brodell, chair of the department of dermatology at the University of Mississippi, tells AARP. Some may have a blue tint and others may appear red, the result of an immune response. “The body is attacking it. It knows it’s abnormal and it’s trying to defend itself, and you get inflammation,” says Brodell. Some cancerous spots lose their pigmentation altogether and leave a halo of white around a darker spot. Buchbinder explains this could be another way the body is attacking the invader and destroys even the normal melanocytes, the cells that produce pigment.

4. Itchy or bleeding spots. According to the Skin Cancer Foundation, any change in size, shape, color or elevation of a spot on your skin, or any new symptoms in it, such as bleeding, itching or crusting, may be a warning sign of melanoma.

If you notice any of these signs or symptoms, or see anything new, changing, or unusual on your skin, see a dermatologist promptly. People on blood pressure medications should also be cautious spending time outdoors as these drugs could make you more susceptible to sunburn, which amplifies your risk of skin cancer and melanoma. Wear protective clothing and sunglasses that block UV rays. Use sunscreen liberally and make sure you choose a sunscreen that is safe, effective and does not contain cancer-causing ingredients and offers broad-spectrum protection.