Six Warning Signs of a Silent Killer Skin Cancer That Can Show Up on Your Feet

We all know to keep an eye on moles and weird spots on our arms or face, but did you know one of the deadliest forms of skin cancer can hide on the soles of your feet or even under your toenails? Experts are urging everyone – yes, literally everyone – to start checking their feet regularly because melanoma on the foot is often missed until it’s already spreading.

Melanoma is the more dangerous type of skin cancer (far less common than the non-melanoma kinds, but much more likely to spread to other organs). Usually we link it to sun exposure, yet it can appear in places the sun barely touches – like between your toes or on the bottom of your foot. Because most of us never think to look there, the cancer can grow quietly for years.

Doctors from the American Academy of Dermatology say that catching it early makes an enormous difference – when it’s still confined to the foot, it’s highly treatable. Let it spread, though, and it can become life-threatening.

Here are the six foot-specific red flags they want you to watch for:

1. A brown or black vertical line that appears under a toenail (it can look like a streak or bruise that won’t grow out).
2. A pinkish-red spot or bump that just shows up out of nowhere.
3. A new dark spot or growth in a place where you once injured your foot – even if the injury was years ago.
4. A mass that seems to grow quickly, especially around an old injury site.
5. A sore on your foot that refuses to heal (or one that heals and then comes right back).
6. An ulcer-like sore that resembles a diabetic foot ulcer, even if you don’t have diabetes.

📷 Close-up of a dark vertical line under a toenail
Photo: Getty Images

Sometimes these spots itch, hurt or bleed on and off, but not always – some people feel absolutely nothing until it’s advanced.

You can also use the classic ABCDE rule on any mole or pigmented patch on your feet:

• A – Asymmetry (one half doesn’t match the other)
• B – Border (irregular, ragged or blurry edges)
• C – Colour (multiple colours or uneven shading)
• D – Diameter (usually bigger than 6 mm, though it can start smaller)
• E – Evolving (changing in size, shape or colour)

How to check properly
The pros recommend a monthly foot inspection:

• Look at the entire sole of each foot (use a mirror or ask someone to help)
• Check the tops and sides
• Spread your toes and look in between
• Inspect under and around every toenail

Pay extra attention to any old scars or places you’ve injured before – research shows past trauma to the foot can slightly raise the risk.

If anything looks odd or worries you, don’t wait – book an appointment with your GP or a dermatologist straight away. A quick check now could save your life later.