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Skin cancer signs: How can you tell if a suspicious spot is serious?


Doctors say changes in the skin are normal as you age, from spots of various colours to dark streaks in nails. But sometimes, they're not innocuous.

With summer here, and more Canadians being exposed to the sun, some may wonder how to tell if a new suspicious spot or growth is something to worry about.

Different types of skin cancers are diagnosed in Canada every day, Toronto-based dermatologist Dr. Renée Beach told daytime talk show The Social in an episode that aired Monday.

If the cancer is spotted early, it can mostly be surgically removed and patients are able to live a regular life, Beach said.

The sun's ultraviolet rays, which damage skin cells, are not the cause of all skin cancers though, experts say.

Beach explains what to look for if you're worried about suspicious skin growths possibly being cancerous.

Types of skin cancer

Basal cell cancer: Sun exposure and sunburns can cause this type of skin cancer, Beach said.

It's the most common form of skin cancer in Canada, but it's the least dangerous, according to the Canadian Dermatology Association. If not treated, it can cause pain, bleeding and disfigurement, it added.

Squamous cell cancer: Along with the sun's harmful rays, squamous cell cancer can be caused from injury to the skin and when the body is immunosuppressed, such as after an organ transplant, she added.

It's the second most common form of skin cancer in Canada, the Canadian Dermatology Association says. It can appear as rough, scaly growths that may be skin-coloured, pink or brown. Treatment is necessary because the tumours become more dangerous the larger they grow, it said.

"A small percentage may spread (metastasize) to lymph nodes and other organs, with potentially fatal results," the association wrote on its website.

Melanoma: Although less common, melanoma can develop into skin cancer as a result of exposure to ultraviolet rays from the sun, as well as genetics. It can show up on the body in places that aren't exposed to the sun, such as the bearded area, genitals, palms or soles, in people of all skin tones, Beach said. Beach recommends men shave their beards once a year so doctors can examine the skin for any potential signs of skin cancer. "Unfortunately, it's associated with the most spread (and) also the lowest rate of survival, so death," she said about melanoma. It will often look brown or black and sometimes other colours.

ABCDE Signs of skin cancer

Beach says the following are potential signs of skin cancer:

  • Asymmetry: One side of a mole or growth doesn't look like the other side.
  • Border: It has a jagged or irregular edge rather than a smooth one.
  • Colour: Part of the skin could have different colours, such as black, brown, white, red or purple.
  • Diameter: Anything on the skin that is five millimetres or greater can sometimes be a red flag. In nails, it's usually a concern if the change is three mm or greater.
  • Evolution: For dermatologists, it's most important to see if something has changed with the skin and doctors aren't able to explain it. "Particularly if the top of it has come off, or it's bleeding, it's an open sore – that isn't considered to be normal," Beach said.

Types of melanoma mimickers 

Sometimes changes in the skin look like melanoma but are actually melanoma mimickers, Beach said.

Cherry angiomas: These are benign growths made of blood vessels or lymphatic vessels. They show up as bumps or papules on any skin type. They can look bright red or have deeper colours. They can also bleed, which is normal. "All of these things can make people concerned but it's not of concern, it's completely normal," Beach said. "We see it in about half the population by the time we hit 50 and about 75 per cent by the time they hit their 70s."

If you are concerned, Beach recommends seeing a doctor. "If they're unsure, they'll send you to a dermatologist," she said. "But the reality is they're normal ... there are more people that would have them than people that would not."

Dermatofibroma: A very common melanoma mimicker, dermatofibroma can occur on anyone's limbs. It may appear after a minor trauma, mosquito bite, a cut while shaving or ingrown hair, Beach said. "Because they're new and they sprout out and they grow, people get really concerned, but they're normal. In fact, I don't even offer to cut them out cosmetically because I find that the cosmetic result is actually worse than the spot itself."

Seborrheic keratosis: Beach says she sees patients every day with this type of melanoma mimicker, also called "granny warts" or "barnacles of aging." The cause is unknown, but they can run in families, she said. "They look the worst," she said, noting they can appear round or oval, brown, black, thick and craggy-looking. They can also be larger than a centimetre and look waxy or scaly. "They're basically your badge for growing into your 30s, so consider it your gift for getting into adulthood," she said. "And they're totally normal."

Seborrheic keratosis will change in size and is one of the common reasons for cosmetic removal, but is not a medical concern, she added.

Nail changes: Beach has observed nail streaking, which appear as brown stripes in the nails, in many olive-, tan- and black-skinned patients. This is an extension of melanin in the skin bordering the lower end of the nail, or proximal nail fold. "It's simply outgrowing with your nail," Beach said. "We see it as a sign of mature skin. There's no reason for concern unless it becomes a black band, in which case I would be more concerned and I'd ask patients to see their doctor."

If it bothers patients, she recommends they just wear nail polish.

Skin cancer treatment

If a skin change is suspected to be melanoma, patients would get a biopsy in which doctors freeze the skin tissue, get samples and obtain a report that determines what it is. Further treatments would follow if needed, she added.


While occasionally wearing sunscreen can't prevent certain skin cancers, it's best to be safe and use sunscreen, doctors say. Research has shown that wearing sunscreen reduces the incidence of skin cancers.

Beach said some social media influencers who helped boost the anti-sunscreen movement are doing a disservice to the public by falsely promoting that sunscreen is toxic or disrupts the body.

"I tell my patients, 'Don't wear sunscreen if you want three things: skin cancer, wrinkles and thin skin, and pigmentation changes, and I have yet to find somebody who actually says, 'OK, then I won't wear it,'" Beach said. "We know these are safe and that they protect us."

Watch the video above for more information, including images of the types of melanoma mimickers. Top Stories

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