Most of us notice something on our skin from time to time and wonder whether it matters. A new spot, a freckle that looks a little different, or a mole that seems to have changed. The reassuring truth is that the vast majority of these changes are completely harmless. Even so, skin cancer is one of the most common cancers, and it is far easier to treat when it is found early, so learning what to look for is genuinely worth your time.
As a Consultant Dermatologist, I spend a good deal of my week reassuring people that a mark they were worried about is nothing to worry about at all. Catching any change early when the lesion is not benign, makes all the difference. This guide walks through what skin cancer can look like, how to check your own skin, and when it is sensible to have something looked at. It is not a substitute for a professional assessment, but it should help you feel more confident about your skin and clearer about when to seek advice. A dermatologist is the best-positioned person to diagnose skin cancer.
What are the early warning signs of skin cancer?
Skin cancer usually shows up in one of two ways: as a brand new mark that appears and sticks around, or as a change in something that was already there. A routine mole check or skin check is one of the most common reasons people come to see us, and the single most useful habit between visits is simply knowing what is normal for your own skin, so that anything new or changing stands out.
The signs I’d encourage people to look out for include:
- A new growth, spot or mole (naevus), particularly one that keeps growing
- A very dark or black lesion
- A sore or scab that does not heal within about four weeks, or that heals and then recurs
- A spot that bleeds, crusts or oozes
- A patch of skin that becomes red, scaly or rough and does not settle
- An existing mole that changes in size, shape or colour
One phrase I often use with patients is to look for the “black sheep of the family”. Most of your moles will tend to resemble one another, so the one that looks completely different from all the rest is the one worth paying attention to.
The three main types, and how they can look
“Skin cancer” is really an umbrella term covering a few different conditions, and they don’t all look the same. The three most common are:
- Basal cell carcinoma (BCC), the most common type. It often appears on sun-exposed areas such as the face, nose, ears or scalp, and can look like a pearly, waxy or translucent bump, or a sore that won’t heal. It usually grows slowly. It usually doesn’t spread throughout the body but can cause local tissue destruction.
- Squamous cell carcinoma (SCC), the second most common. It tends to appear as a firm, scaly or crusty plaque or lump, sometimes tender, again often on sun-exposed skin. It has the ability to spread throughout the body and so is more serious than a BCC.
- Melanoma, which is less common but the most serious, because it is more likely to spread if it is not caught early. It can appear as a new, unusual mole or as a change in an existing one, and colour variation, irregular edges or asymmetrical growth are the most common features noted.
The incidence of all three main types of skin cancer is increasing in the United Kingdom.
How skin cancer can look on darker skin tones
Skin cancer can affect people of every skin tone, although it is more common on lighter skin tones. It is, however, a common misconception that darker skin is not at risk. It can be, and because people don’t expect it, it’s sometimes caught later. On brown and black skin, melanoma more often appears in less sun-exposed areas, such as the palms of the hands, the soles of the feet, or under a finger or toenail, where it may show as a dark streak or patch. Any new or changing mark in these areas is worth having checked.
What does a cancerous mole look like?
In this short video, I explain the idea of the “black sheep of the family”, the mole that looks completely different from the others, and the changes worth noting at home, such as a mole that is growing quickly or has more than one colour within it.
The ABCDE rule: how to check a mole at home
The ABCDE rule is a simple tool we use in the clinic to assess moles, and it works just as well as a guide for checking your own skin at home. Each letter points to a feature worth noticing:
- A is for Asymmetry. If you imagine a line through the middle of the mole, do the two halves match? Cancerous moles are often asymmetrical.
- B is for Border. Harmless moles tend to have smooth, even edges. Irregular, blurred or jagged borders are more of a concern.
- C is for Colour. A single, even shade is reassuring. Uneven colour is worth noting. Having several colours within one mole rings alarm bells.
- D is for Diameter. Larger moles, particularly those bigger than about 6mm (roughly the size of a pencil-end), deserve a closer look.
- E is for Evolving. This is the most important of all. Any mole that is changing over time, in size, shape, colour or how it feels, should be assessed.
If a mole ticks one or more of these, it does not mean it is cancer. Plenty of harmless moles have an irregular feature or two. But it does mean it is worth having looked at, and evolution in particular is the one I’d never ignore. We do not expect you to diagnose a melanoma at home, but it is good to be able to tell if something is changing or ‘just doesn’t look right.’
What is the ABCDE rule for melanoma?
Here I talk through each step of the ABCDE rule and how to apply it at home, and explain why any of these signs, or simply being concerned about a mole, is a good reason to arrange an appointment.
Can skin cancer itch, bleed or feel sore?
Yes, it can, and this is something people often don’t expect. There is a common assumption that skin cancer must be painful or dramatic to be serious, but the opposite is usually true. Many skin cancers are painless, especially in the early stages, which is exactly why appearance and change matter more than how something feels.
That said, certain sensations are worth taking seriously. A mole that itches persistently, feels tender, or develops a sore or crust that keeps coming back should be checked, even if it seems minor. Any lesion that bleeds spontaneously (i.e. not after being scratched or caught on clothing) needs immediate attention. As I often put it: if something on your skin looks or feels different and it isn’t settling, it is better to have it seen than to wait.
Is it skin cancer, or something harmless?
Most spots that people bring to the clinic turn out to be entirely benign, and it helps to know the usual suspects. A few common, harmless things are often mistaken for something more serious:
- Skin tags are soft and tend to move easily. Cancerous spots are usually firmer and fixed in place.
- Seborrhoeic keratoses (sometimes called age spots or “barnacles”) are common, warty-looking growths that are harmless, though they can look alarming.
- Cherry angiomas are small, bright red spots that are benign. Their correct term is a Campbell-de Morgan lesion.
- Moles and freckles that have looked the same for years are usually nothing to worry about.
Harmless age spots and warty growths like these are among the things we reassure people about most often in the clinic, and where one is bothersome it can usually be treated simply. The key theme running through all of these is stability. Things that have been the same for a long time are generally reassuring. It is change, a spot that is new, growing, or behaving differently from everything around it, that warrants a closer look. If you are ever unsure which category something falls into, that uncertainty is itself a good reason to get it checked.
How quickly can melanoma and other skin cancers grow?
In this short video I explain that skin cancers grow at different rates, and why it’s worth acting quickly if you notice a mole or spot changing rapidly.
When to see a dermatologist about a changing mole
A changing mole is one of the most common reasons people come to see us, and I’d always rather someone came in and was reassured than held off and worried. It is worth arranging an assessment if you notice any of the following:
- A mole or spot that is changing in size, shape or colour
- A new growth that keeps growing
- A sore or patch that does not heal within about four weeks
- Anything that bleeds, itches or crusts and does not heal or resolve
- A mole that simply looks different from all your others
It is worth saying clearly: a mole changing does not mean it is cancer. Moles can and do change in completely harmless ways throughout life. The point of an assessment is not to assume the worst, but to get clarity quickly, which usually means reassurance, and occasionally means catching something early when it is at its most treatable. We also see a good number of people who have had a mole removed or a skin cancer treated in the past and come back for regular checks, as part of an ongoing surveillance programme. If you are at higher risk for skin cancer, that kind of ongoing surveillance is exactly the sort of thing worth keeping up.
Whilst anyone can develop skin cancer, there are a few groups of people who are at higher risk. These include people who have:
- fairer skin types
- had periods of harsh sun exposure as a child
- ongoing high sun exposure such as outdoor workers
- used sunbeds extensively
- an increased number of naevi (moles) especially if the naevi are large
- a past history of skin cancer
- a first-degree relative with skin cancer
- being on or are taking immunosuppressive medication
- Dysplastic Naevus Syndrome
- some rare genetic conditions which predispose you to skin cancer
Is every changing mole cancer?
Here I explain that a changing mole is very often benign, while explaining why it is still sensible to have any changing mole checked, just to be on the safe side.
When you do come in, the assessment itself is straightforward. We take a history, examine your skin with a dermatoscope (a special magnifier that improves diagnostic accuracy) ,take clinical photos and if anything looks suspicious we can arrange a biopsy or removal of the lesion.
Frequently asked questions
What is usually the first sign of skin cancer?
Most often it is a change: a new mark that appears and persists, or an existing mole that starts to look or behave differently. A sore that does not heal within about four weeks is another common early sign. Because the first signs can be subtle, knowing what is normal for your own skin is the best way to notice when something is not.
Can you have skin cancer for years without knowing?
Some skin cancers, particularly basal cell carcinomas, grow very slowly and can be present for a long time before they are noticed. That is one reason regular self-checks and prompt assessment of anything unusual are so useful.
Does skin cancer always look like a mole?
No. It can look like a mole, but it can also appear as a scaly patch, a pearly or waxy bump, a sore that will not heal, or a firm red lump. This is why any persistent new or changing mark, not just moles, is worth having assessed.
Should I get a mole checked even if I’m probably overreacting?
Yes. I’d always rather see someone and reassure them than have them wait. There is no such thing as wasting a dermatologist’s time with a mole you are worried about, and if it does turn out to need treatment, catching it early is a real advantage.
Getting peace of mind about your skin
If you have noticed a new or changing spot, or you would simply feel reassured by having your skin checked over, we are here to help. The great majority of the marks we see are harmless, and where they are not, early assessment gives the best possible head start.
To arrange a skin check or discuss a mole you are concerned about, book an appointment with one of our Consultant Dermatologists at The London Skin and Hair Clinic.
About the author: Dr Martin Wade is a Consultant Dermatologist at The London Skin and Hair Clinic. Australian-trained and registered with the General Medical Council on the Specialist Register for Dermatology, he specialises in skin cancer, hair loss and scalp conditions, and acne. Read more about Dr Wade and book a consultation on his profile.