Reasoning GP · Algorithm · 1-page summary
Pigmented skin lesions
For: adults and children with a new, changing or worrying pigmented lesion, or a growing pink or flesh-coloured nodule, in primary care. Not for: AK treatment detail (use the actinic keratosis protocol) or other nail problems (use the nail disorders protocol).
Core rule: change is the cardinal warning sign. Score every worrying lesion on the NICE weighted 7-point checklist, remember nodular and amelanotic melanoma can lack ABCDE features, and if melanoma is suspected refer — never partial biopsy or non-specialist excision.
0Act now — rarely an emergency, but do not miss these
- Acute uncontrolled bleeding, severe infection or airway compromise from a lesion → Same-day ED. ED is not the route for a suspicious lesion itself.
- On checkpoint immunotherapy for melanoma with a new organ symptom (diarrhoea or bloody stool, new breathlessness, severe or blistering rash) → consider an immune-related adverse event and contact oncology Urgent
- Suspected melanoma: suspected cancer pathway referral; do not take a partial biopsy or excise it yourself. Photography must not delay the referral.
1Triage — NICE weighted 7-point checklist
| Feature | Points |
|---|---|
| Major | Change in size · irregular shape · irregular colour — 2 each |
| Minor | Diameter ≥7 mm · inflammation · oozing · change in sensation — 1 each |
| Score ≥3 | → Suspected cancer pathway |
| Score <3 | High clinical concern → still refer on the suspected cancer pathway |
ABCDE and the “ugly duckling” sign are supplementary prompts. Evolution (any change) is the most important single feature.
2Screen — suspected cancer pathway (diagnosis within 28 days)
- Dermoscopy by a trained clinician suggests melanoma, or new pigmented lesion changing rapidly over weeks in any adult → Refer
- Lesion suggesting nodular melanoma, pigmented or not (elevated, firm, growing; bleeding or ulcerated) → Consider referral
- Suspected lentigo maligna (large, irregular, slowly spreading flat facial patch, older person) or nail: widening or irregular pigmented band, Hutchinson's sign → Refer
- Child or young person with change, irregular border or bleeding → Refer via local paediatric dermatology.
- Previous melanoma, new or changing lesion → specialist service per the follow-up plan; meets criteria → Refer
- Suspected SCC; BCC where site or delay could affect outcome → Consider referral
3Assess
☐ Change, symptoms, duration, sunburn and skin type, previous melanoma or family history, immunosuppression ☐ Whole skin and nails ☐ Dermoscopy only if trained ☐ Record site, maximum diameter (mm), evolution; photograph with a scale where permitted
Not in primary care: partial biopsy or excision of a suspected melanoma.
4Classify — reassure only if the diagnosis is clinically secure
- Common naevus — symmetrical, uniform colour, regular border, stable → reassure; return if it changes.
- Seborrhoeic keratosis — waxy “stuck-on”, well defined → reassure. Sudden eruption of many → think of internal malignancy (Leser-Trélat).
- Solar lentigo, dermatofibroma (dimples on pinching), cherry angioma → reassure.
- Pyogenic granuloma — fast-growing, bleeds easily; can mimic amelanotic melanoma → refer for excision. Spitz naevus in a child → refer.
- Actinic keratosis — rough, scaly, sun-exposed. Thick, tender, ulcerated, bleeding or fast-growing → assess for SCC.
- Uncertain or equivocal → refer rather than reassure.
5Treat today — only these
- Awaiting a melanoma appointment: keep the area out of the sun; no manipulation or treatment of the lesion. Do not promise an appointment within 2 weeks.
- Single uncomplicated AK (competent, not suspicious for SCC) → cryotherapy. Field AK → fluorouracil 5% with counselling: expected inflammation; stop and seek review for severe pain, ulceration, infection or eye exposure. Regimen per SPC; doses: NICE/SPC, BNF, local formulary.
- Excised lesions → histology per local skin cancer/pathology policy; always where melanoma or another skin cancer is possible.
- Sun protection: shade, clothing, hat, no sunburn, no sunbeds; sunscreen SPF ≥30 with good UVA protection as an adjunct. Teach self-examination.
6Refer routinely
- Suspected BCC → local dermatology/skin-cancer pathway; low-risk only by a GPwER under local protocol.
- Multiple or refractory AK; equivocal lesion not meeting urgent criteria → dermatology.
- Large or atypical congenital naevus, multiple atypical naevi, suspected familial melanoma → dermatology or genetics.
- Previous melanoma or high risk → follow the specialist surveillance plan, not an annual GP skin check.
7Never reassure by
- Regular borders or no ABCDE features (nodular melanoma).
- A pink or flesh-coloured colour (amelanotic melanoma).
- A diameter under 6 mm.
- A checklist score below 3 when you are still worried.
- A photograph review that delays a referral.
- Young age: childhood melanoma is rare but occurs.
8Safety-net — say it, then document it
Same week “Come back within the same week if a mole changes in size, shape or colour, grows quickly, bleeds without injury, ulcerates, becomes painful, keeps itching or crusting, or a new mole appears.”
Referred: “The aim is a diagnosis within 28 days. If it changes, bleeds, ulcerates or hurts before then, contact us or dermatology the same week. Go to A&E only for bleeding that won't stop, severe infection or breathing problems.” Record the referral date and chase it. Declined referral: document informed refusal and safety-net.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Whole skin and nails examined; 7-point score recorded
Diagnosis clinically secure (not equivocal)
Site, size in mm and change recorded; photo with scale
Safety-net and sun advice given
Summary of the full Reasoning GP pigmented skin lesions algorithm, which holds the detail, dermoscopy, AK and BCC management and evidence. Sources: NICE NG12 (updated April 2026), NG14, NG34; BAD BCC guideline 2021; SPCs. Clinical reference — follow local skin-cancer pathways and check doses: NICE/SPC, BNF.