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Purpose and principlesIndications, selection and cautionsMethod and interpretationClinical next stepsRisks, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

ABCDE and ugly-duckling assessment of pigmented lesions

Dermatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Purpose and principles

Assess a pigmented lesion systematically, compare it with the patient’s mole pattern, use the weighted seven-point checklist correctly, and arrange urgent specialist assessment without unsafe destructive sampling.

Begin with the story: when first noticed, change in size, shape, colour or elevation, bleeding, crust, itch or pain, previous melanoma, family history, ultraviolet exposure, sunbeds, immune suppression and photographs. Ask what prompted concern. A lesion can be clinically important even when the patient cannot date its onset, particularly on scalp, back, acral sites or beneath a nail.

Examine the lesion and its context in bright light. Record dimensions in millimetres, site, symmetry, border, colours, surface, palpability, ulceration and nodes when indicated. Compare with nearby and distant naevi to identify an ugly duckling. In richly pigmented skin, melanoma may arise acrally or under nails and colour contrast can be subtle; assessment must include palms, soles and nail units rather than focusing only on sun-exposed sites.

ABCDE and the seven-point checklist are decision aids, not exclusion tests. Seborrhoeic keratoses, haemangiomas and pigmented basal-cell carcinoma can mimic melanoma, while amelanotic melanoma may be pink or skin-coloured. A rapidly growing firm nodule, persistent nail band with periungual spread or any lesion that conflicts with the patient’s usual pattern deserves escalation despite a low arithmetic score.

Key points

  • ABCDE prompts asymmetry, border irregularity, colour variation, diameter and evolution; evolution is often the most useful single feature.
  • The ugly-duckling sign identifies a lesion that differs from the person’s background naevus pattern, even if it does not satisfy every ABCDE letter.
  • Nodular melanoma may be symmetrical, uniformly coloured and initially small; use elevated, firm and growing over weeks to months as an additional warning pattern.
  • NICE weighted seven-point major features—change in size, irregular shape and irregular colour—score 2 each; minor features score 1 each.
  • Minor features are diameter 7 mm or more, inflammation, oozing and change in sensation; a total of 3 or more triggers urgent suspected-melanoma referral.
  • Examine all skin, including scalp, nails, palms and soles, with informed consent and a chaperone where preferred; do not assume low risk from skin tone.
  • Dermoscopy by a trained clinician improves diagnostic accuracy but does not make a changing suspicious lesion safe for routine review.
  • Do not curette, cauterise, freeze or partially sample a possible melanoma in primary care; urgent specialist full-thickness excision planning preserves staging.

Indications, selection and cautions

Asymmetry

One half differs from the other in outline, colour, structure or elevation when imagined across more than one axis.

Irregular border and colour

Notches, projections, fading edges and multiple uneven shades of brown, black, red, blue, grey or white increase concern.

Evolution

Documented or credible change in size, shape, colour, surface, symptoms or elevation is a major warning even below 7 mm.

Ugly duckling

A lesion that looks unlike the patient’s otherwise similar naevi can expose malignancy that appears individually orderly.

Nodular growthRed flag

A new elevated, firm and continuously growing papule or nodule over weeks to months can be melanoma without classic ABCD asymmetry.

Acral or nail warningRed flag

An enlarging irregular palm or sole macule, broad changing nail band, nail dystrophy or pigment on adjacent skin requires urgent specialist review.

Red flags requiring action

  • Evolution, an ugly-duckling lesion, nodular growth, bleeding, ulceration, irregular colour or shape, nail-unit pigment extending onto skin, or a weighted seven-point score of 3 or more requires urgent suspected-cancer referral.

Method and interpretation

  1. 01
    Weighted seven-point checklistFirst step
    Why
    Standardise urgent-referral assessment of a suspicious pigmented lesion.
    Interpretation and limitations
    Score major change in size, irregular shape and irregular colour as 2 each and minor diameter, inflammation, oozing and sensation as 1; refer at 3 or more.
  2. 02
    Whole-skin and ugly-duckling comparison
    Why
    Find additional lesions and identify an outlier within the patient’s personal naevus phenotype.
    Interpretation and limitations
    Obtain consent for examination and images, preserve privacy and inspect scalp, acral skin and nails; a single outlier can outweigh reassuring symmetry.
  3. 03
    Dermoscopy by a trained clinician
    Why
    Assess pigment network, asymmetry, blue-white structures, atypical vessels and melanoma-specific acral or nail patterns.
    Interpretation and limitations
    Dermoscopy refines rather than replaces referral judgement and should not delay urgent assessment of a clearly evolving lesion.
  4. 04
    Baseline clinical photography
    Why
    Document size and morphology for selected specialist-led surveillance or comparison.
    Interpretation and limitations
    Use explicit consent, scale, consistent lighting, secure storage and a defined review date; photography is unsafe as indefinite watchful waiting for a suspicious lesion.

Clinical next steps

01Suspicious pigmented lesionRefer on pattern and evolutionFirst stepThe weighted checklist scores 3 or more, dermoscopy suggests melanoma, or an ugly-duckling, nodular, acral or nail warning exists.+
  1. 1Document history, measurements, morphology, patient’s comparison pattern and relevant risk factors without attempting destructive treatment.
  2. 2Make an urgent suspected-cancer referral using the local pathway and attach consented images only when secure systems and policy allow.
  3. 3Explain referral urgency without declaring a diagnosis, safety-net further growth or bleeding and ensure the patient knows how the appointment will arrive.
02Apparently benign lesionUse explicit safety-nettingAssessment is clinically reassuring and no significant evolution, outlier pattern or high-risk context is present.+
  1. 1Name the likely diagnosis and record dimensions and key reassuring features rather than writing simply benign mole.

Risks, monitoring and follow-up

  • Track referral receipt and outcome rather than assuming transmission of an electronic request completes the safety pathway.
  • For surveillance, compare exact millimetre measurements and standardised images at a predefined interval and escalate any objective evolution.
  • After a benign specialist diagnosis, retain return advice for change because a future new lesion may carry different risk.
  • Patients with previous melanoma or multiple atypical naevi need risk-stratified specialist follow-up, not repeated isolated lesion checks.
  • Audit urgent referrals for complete lesion description, seven-point score, photographs where appropriate and correct contact details.

Special situations

Evolution beats diameter

A melanoma can be smaller than 7 mm; credible change should never be neutralised by a ruler.

The patient supplies a comparator

People often recognise that one lesion behaves or looks unlike their stable moles before a clinician does.

Nodular melanoma breaks ABCD

Rapidly growing firm elevation may lack broad asymmetry or colour variation yet carries substantial thickness risk.

Acral examination is universal

Palms, soles and nails require examination in every skin tone when symptoms or a full skin check makes them relevant.

Photography needs ownership

An image without a defined reviewer, interval and escalation threshold creates documentation without surveillance.

Common pitfalls

  1. 01

    Reassuring a changing 5 mm lesion because it has not reached the minor-feature diameter threshold.

  2. 02

    Using symmetry to dismiss a rapidly growing firm nodule and missing nodular melanoma.

  3. 03

    Examining only sun-exposed skin in a dark-skinned patient and omitting soles and nails.

  4. 04

    Freezing a pigmented lesion before diagnosis and destroying the tissue needed for staging.

  5. 05

    Taking photographs without consent, secure storage or a named follow-up decision.

Practice

Two practice questions

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Question 1 of 2
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DermatologyOriginal SBA

Small lesion that is changing

A 5 mm pigmented lesion has enlarged and developed irregular colour over three months. It differs from all the patient’s other moles. What is the best action?

Choose one answer, then submit
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Sources and review status3 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG12 suspected skin cancer recommendationsWeighted checklist and urgent melanoma, SCC and BCC referral.
  • NICE NG14 melanoma assessment and managementDermoscopy, photography, biopsy and specialist assessment.
  • NHS melanoma skin cancerClinical warning features, diagnosis, treatment and follow-up.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
05
Specialist full-thickness excision biopsy
Why
Establish histological diagnosis and Breslow depth when melanoma is suspected.
Interpretation and limitations
Remove the whole lesion with a narrow clinical margin and adequate depth where anatomically feasible; avoid shave, curettage or destructive treatment that compromises staging.
  • 2Discuss self-awareness using the patient’s own mole pattern and advise return for any evolution, new symptoms or a lesion that becomes different.
  • 3Use planned photographic review only when clinically justified, with a named interval and clinician ownership rather than patient anxiety alone.
    • 03Uncertain assessmentSeek expertise instead of sampling badlyAnatomy, pigmentation, inflammation, nail location or limited dermoscopy experience prevents confident classification.+
    1. 1Treat diagnostic uncertainty as meaningful, especially for a changing solitary lesion or a patient with previous melanoma or immune suppression.
    2. 2Use advice-and-guidance or urgent referral according to risk, preserving the lesion intact for specialist dermoscopy and biopsy planning.
    3. 3Do not freeze, shave or punch only the darkest part because an incomplete specimen can underestimate melanoma architecture and depth.