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Skin Blemishes - What To Look Out For


Skin cancer is common and you shouldn’t hesitate to see a doctor if you are concerned.

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How do I know if any of my skin blemishes could be cancerous?

Below I will give you some simple rules of thumb which cover most eventualities with skin blemishes that are worrying. We will also discuss how moles and blemishes can be removed and treated.


It might be surprising to hear but it’s thought that the majority of skin cancers arise from normal skin – It’s far less common than an existing blemish turns cancerous. If an existing blemish or mole appears to change, it may be that it always had some cancerous changes within but has now shown its true colours. Your number one tip, therefore, is to learn to recognise what blemishes you have or what sorts of blemishes you are prone to.

Taking pictures of your skin every 6-12 months, perhaps with the help of a partner, can be very useful.

Schematic structure of skin


It follows from rule 1 above that you need to look for a mole or blemish which looks or is behaving differently. If you spot something which you are unsure about, look elsewhere on your skin for something which looks very similar. If you can’t find a similar mole or lesion – consult a doctor.

Following these first 2 rules will go a long way on their own in protecting you from serious cancer developing on your skin.

An 'ugly duckling' (melanoma)


Most people nowadays wouldn’t put off going to see a doctor if a mole or skin lesion is growing or changing quickly. When I say quickly, that means over the course of some weeks. A slower change of a FLAT skin lesion (one you can’t feel when you run your finger over it) can be monitored safely until it reaches a size of the end of a pencil (6-7 mm). A growing nodular lesion or mole (one you can feel with a finger) should prompt you to seek advice as soon as practical.

Don’t ignore a rapidly changing skin blemish and book to see a doctor urgently.

Modular melanoma


This is my short-hand for the ‘ABCDE’ rule, which you may have heard of. I personally think this rule is over-complex and I don’t usually spend too much time talking about it to patients. It’s a way to describe asymmetry (A), change in the border (B), colour (C), diameter (D) and whether it is evolving (E). If you can remember what the letters stand for, by all means, use the ‘ABDCE’ rule!

But you can also simply think of an island holiday in the sun – is a mole starting to look like an island from the air? Maybe you can remember being sunburnt on one of these islands in the past?

Superficial spreading melanoma


Many harmless skin blemishes and moles can bleed or develop a crust from minor trauma such as catching on a nail or clothing. If this keeps happening and it isn’t healing over a month or so it is wise to have it checked out as it could mean something is amiss.

Wash the area gently with soap and water once a day, but don’t disturb any crust and allow this to drop off naturally. Keeping a wound covered with a plaster or using simple Vaseline over it 3 times a day will help it to heal quicker.

Basal Cell Carcinoma


Whilst it is true that skin cancer might itch or be painful, these symptoms are also very common in harmless blemishes. They are therefore not a useful predictor of skin cancer on their own. But if you have noticed any of the changes described in the other rules above AND itching or pain, then this should prompt you to have the mole blemish examined by a doctor.

Persistent itching and pain can mean that a blemish is being irritated by friction, for example from your work or sport, or rubbed by clothing. Try keeping the blemish covered or apply a moisturiser daily to an itchy or painful blemish.

Itching on its own is unlikely to be a problem


Another useful rule is to be more suspicious of single lesions. You might develop a ‘verruca’ or some sort of repeat trauma to an area of your body, such as a finger or toe and falsely attribute this to harmless changes. Some skin cancers can grow very slowly and not look particularly worrisome in themselves.

The lonely skin lesion IS an ‘ugly duckling’! But don’t feel sorry for it – get it checked out and removed if advised!


Skin cancer is common and you shouldn’t hesitate to see a doctor if you are concerned. The good news is that skin cancer can be cured, provided you don’t wait too long to get things checked out. The vast majority of skin cancers grow pretty slowly and you can observe your blemishes safely for a good few weeks before booking an appointment. Fast-changing blemishes (over weeks) are unusual, but these should be biopsied or removed urgently for diagnosis and treatment.

A biopsy or skin lesion removal is no big deal, by the way. If you see an experienced doctor, who has removed a lot of skin lesion he or she will be skilled at minimising any discomfort from a local anaesthetic. If you are not good with needles then tell the doctor when you see him or her – they can consider a local anaesthetic cream for an hour or so before any injection and this can render a procedure next to pain-free.

Sometimes moles & skin lesions can cause people nuisance by catching on clothing or hair care. They may also be unsightly and affect your confidence. Most of the time these can also be treated, but this would normally not be supported on the NHS. There are many ways to biopsy or remove a skin blemish – you can read about these here.

Which type of doctor should I see?

It is a sad fact that most universities and medical schools provide only a few hours or days training in recognising skin disease and skin cancer. Make sure that the doctor you have booked to see knows what they are doing – don’t be afraid to ask them about their training and experience. Ask if they have received training in dermoscopy (see photo above) – this is a specialist tool to aid diagnosis of skin cancer. Some GPs have undergone such training and you can ask the receptionist when booking your appointment. If you feel that you have not received the reassurance you need, ask for a second opinion or a referral to a skin specialist.

Written by James Dean
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