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Health condition · Clinically reviewed

Moles, the ABCDE rule - and knowing when to get one checked.

Almost everyone has moles, and almost all of them are harmless. Knowing what’s normal for your skin is what makes a genuine change easy to spot.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE NG12 and British Association of Dermatologists sources you can see at the end.

  • 03

    Current for 2026

    Reflects current UK pathways for dermoscopy, mole mapping and two-week-wait referral.

Key facts

Moles at a glance.

The essentials, in plain English - what they are, the types, and how they’re assessed in the UK today.

  • What it is

    A benign cluster of pigment-producing cells (melanocytes) - almost every adult has several, and most never cause a problem.

  • Congenital naevi

    Present at birth - size ranges from a few millimetres to giant lesions, which carry a higher lifelong melanoma risk and need surveillance.

  • Acquired naevi

    The most common type - appear through childhood and early adulthood, then often stabilise or fade with age.

  • Atypical naevi

    Irregular in shape, border or colour but still benign - numerous atypical moles can signal a higher overall melanoma risk.

  • Blue naevi

    A blue-grey lesion caused by pigment sitting deeper in the skin rather than a different type of cell.

  • The main concern

    Telling a benign mole apart from melanoma - the ABCDE rule and the “ugly duckling” sign are the two tools that matter most.

Why this guide matters

Knowing what’s normal is the whole point.

Moles are common, mostly harmless and worth understanding - the three points below shape everything else on this page.

  • Most moles need nothing at all

    Reassurance and simple self-awareness are the right answer for the vast majority of moles you’ll ever have.

  • The ABCDE rule is a filter, not a diagnosis

    It flags moles worth a professional look - it doesn’t replace one, and no single feature is decisive on its own.

  • The ugly duckling sign catches what ABCDE misses

    A mole that simply looks different from the rest can be significant even without classic ABCDE features.

How the assessment is made

From a quick look to a clear answer.

The steps a UK GP or dermatologist will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    Visual assessment

    Size, shape, colour and border checked against the ABCDE features, and compared with the patient’s other moles.

  2. 02

    Assessing

    The ugly duckling sign

    A mole that looks noticeably different from its neighbours is a recognised red flag, even without classic ABCDE features.

  3. 03

    Assessing

    7-point checklist

    A weighted score combining major features (change in size, shape or colour) and minor features (diameter, inflammation, oozing, altered sensation).

  4. 04

    Confirming

    Dermoscopy

    A dermatoscope examines the pigment pattern in detail, improving accuracy well beyond the naked eye - GP or specialist with training.

  5. 05

    Confirming

    Mole mapping

    Total body photography for patients with many atypical moles or a strong family history, used to track subtle change over time.

  6. 06

    Deciding

    2-week-wait referral

    Any mole with suspicious features on the checklist is referred urgently to specialist dermatology.

  7. 07

    Deciding

    Excision biopsy

    Definitive diagnosis where malignancy is possible - the lesion is removed and sent for histopathology.

Typical timeline: a routine mole is usually assessed and reassured at the first visit.

Types and features

What moles actually look like.

From ordinary acquired moles to the features that mean it’s time for a specialist look.

  • Congenital naevus

    Present since birth - larger lesions are followed up long-term because of higher lifelong melanoma risk.

  • Acquired naevus

    The everyday mole - appears in childhood or early adulthood and usually stays stable.

  • Atypical (dysplastic) naevus

    Somewhat asymmetric, irregular-bordered or multi-coloured, but benign - warrants monitoring, especially if numerous.

  • Blue naevus

    A blue-grey, dome-shaped mole - the colour comes from deeper pigment, not from a different cell type.

  • Asymmetry and irregular borders

    One half not matching the other, or a ragged, notched edge - both are ABCDE features worth a check.

  • Colour variation

    Multiple shades of brown, black, red or white within one lesion, rather than a single even tone.

  • A changing mole

    Growth, itching, bleeding, crusting or a new mole appearing after age 40 - the “evolving” E in ABCDE.

  • Red flag - suspicious features

    Diameter over 6mm, an ugly duckling appearance, or rapid change deserves urgent specialist assessment.

Management

How moles are managed in the UK.

Reassurance and sun protection for most, structured surveillance for atypical or high-risk moles, and excision where there’s any doubt.

  • Reassurance

    The overwhelming majority of moles are entirely benign and need no treatment beyond awareness of their normal appearance.

  • Self-examination education

    Regular skin checks and familiarity with the ABCDE features, particularly important with many moles or a family history.

  • Sun protection

    Broad-spectrum sunscreen, covering up and avoiding peak sun - UV exposure is linked to both new moles and melanoma risk.

  • Monitoring and surveillance

    Regular specialist review with mole mapping for atypical moles, large congenital naevi or a strong family history.

  • Surgical excision

    Removal under local anaesthetic with histopathology for any mole with concerning features, or one that catches on clothing or shaving.

  • Cosmetic removal

    For benign moles causing cosmetic concern with no medical indication - generally a private rather than NHS service.

  • Genetic counselling

    Selective, for families whose pattern of melanoma suggests a hereditary melanoma syndrome.

  • MDT and pigmented lesion clinics

    Specialist dermatology, plastic surgery and the British Association of Dermatologists work together on complex or high-risk cases.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or dermatologist knows your skin and history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Suspected cancer: recognition and referral (NG12).

  • British Association of Dermatologists (BAD). Patient information on moles and melanoma.

  • British Association of Dermatologists. Revised UK guidelines for the management of cutaneous melanoma.

  • Cancer Research UK. Melanoma skin cancer risk factors and signs.

Red flags

When a mole needs urgent attention.

Most moles are entirely normal. These are the features that mean a mole should be assessed promptly.

  • Asymmetry

    One half of the mole doesn’t match the other - the “A” in ABCDE and a reason for assessment.

  • Border irregularity

    Ragged, notched or blurred edges rather than a smooth, well-defined border.

  • Colour variation

    More than one shade of brown, black, red, white or blue within the same lesion.

  • Diameter over 6mm

    Larger than a pencil eraser - not diagnostic alone, but one of the five features to weigh together.

  • Evolving or changing

    Any new growth, change in shape, colour, elevation, itching or bleeding over weeks to months.

  • Ugly duckling sign

    A mole that looks different from all the others on the body, even if no single ABCDE feature stands out.

  • New mole after 40

    New moles appearing later in adulthood are less common and worth a specialist look.

  • Giant congenital naevus

    Large lesions present from birth carry a higher lifelong melanoma risk and need long-term surveillance.

  • Bleeding, crusting or oozing

    A mole that bleeds without obvious injury, or won’t heal, needs prompt assessment.

Living with it

Ordinary skin, watched sensibly.

Four things that make the biggest difference day to day - knowing your own moles, protecting your skin, checking monthly and acting on change.

A quiet reminder

Familiarity is your best early-warning system.

You don’t need to memorise every mole - you just need to notice when one stops looking like itself.

  1. 01 Routine

    Know your moles

    Take stock of what’s normal for you - number, size and pattern - so a genuine change stands out sooner.

  2. 02 Sun

    Protect your skin daily

    Broad-spectrum SPF, protective clothing and avoiding peak sun reduce both new moles and melanoma risk over time.

  3. 03 Checks

    Do a monthly self-check

    A few minutes with a mirror, front and back, catches most changes early - use the ABCDE rule as your guide.

  4. 04 Escalate

    Don’t wait on a changing mole

    If something looks different, is changing, or simply worries you, get it seen rather than watching and waiting.

Frequently asked

Everything we get asked about moles.

Quick answers on types, the ABCDE rule, monitoring and removal.

  • What is a mole?

    A benign cluster of melanocytes, the cells that produce skin pigment. Most adults have somewhere between 10 and 40, and their number and appearance are shaped by genetics and sun exposure.

  • What is the difference between congenital and acquired moles?

    Congenital moles are present at birth and can range from tiny to giant, with larger ones carrying an increased lifelong melanoma risk. Acquired moles develop later, usually through childhood and early adulthood, and are the far more common type.

  • What does the ABCDE rule mean?

    It stands for Asymmetry, Border irregularity, Colour variation, Diameter over 6mm and Evolving or changing. No single feature is diagnostic on its own, but together they help identify moles that need a specialist look.

  • What is an atypical or dysplastic mole?

    A mole with somewhat irregular features - asymmetry, an uneven border or varied colour - that is still benign. Having several atypical moles, particularly with a family history of melanoma, is associated with a higher overall melanoma risk and usually warrants monitoring.

  • When should I see a doctor about a mole?

    If it shows any ABCDE features, looks different from your other moles (the “ugly duckling” sign), is new after the age of 40, or bleeds, itches or won’t heal. Your GP can examine it and refer urgently if needed.

  • Can moles be removed for cosmetic reasons?

    Yes, benign moles causing cosmetic concern can usually be removed privately by a dermatologist, though this isn’t routinely funded on the NHS. Any mole removed for medical reasons because of suspicious features is always sent for histopathology.

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