GMC-Registered · UK skin cancer specialist
Dermatologist's quick take
- Solar lentigines (sun spots) are flat, uniform, and don't change — harmless cosmetic
- Actinic keratoses are scaly, rough, persistent — pre-cancerous, treat them
- Basal cell carcinoma: pearly bump that bleeds, often on face, slow-growing
- Squamous cell: scaly, ulcerated, can grow rapidly, more dangerous than BCC
- Melanoma: pigmented, asymmetric, changing — the deadliest but most curable when caught early
I'm Dr. Iwasa, a UK-based dermatologist. The single hardest call patients make is whether the brown patch on their cheek is "just sun damage" or something that needs a biopsy. The good news: most pigmented lesions in adults are harmless. The bad news: the few that aren't can kill you, and they often hide in plain sight.
This guide gives you a clear visual framework. For ongoing monitoring, use ScanSkinAI's free AI skin analysis to triage anything that worries you.
Solar lentigines vs actinic keratoses
The first split is between flat pigmented spots and rough scaly patches.
Solar lentigines (sun spots)
- Light to dark brown, uniform colour
- Smooth surface — invisible to touch
- Sharp, regular borders
- Stable for years, no change
- Cosmetic only — not pre-cancerous
Actinic keratoses
- Pink, red, or skin-coloured
- Sandpapery texture, sometimes tender
- Persistent or recurring
- Pre-cancerous — ~10% become SCC
- Treat with cryo, 5-FU, or PDT
The three skin cancers — what to look for
Basal cell carcinoma (BCC)
The most common cancer in humans. Slow-growing, rarely metastasises, but locally destructive. Classic appearance: a pearly, slightly translucent bump on sun-exposed skin — face, ears, scalp, neck. Often has visible fine blood vessels (telangiectasias) on the surface. May develop a central crater or repeatedly bleed and crust. If a "pimple" hasn't healed in 4 weeks, think BCC.
Squamous cell carcinoma (SCC)
Second most common. Often arises from an actinic keratosis. Appears as a scaly, red, crusted patch or a firm nodule, often tender. Can grow rapidly. Higher metastasis risk than BCC, especially on lips, ears, and in immunosuppressed patients. Any persistent rough patch or non-healing ulcer needs assessment.
Melanoma
The deadliest but most curable when caught early. Use the ABCDE rule: Asymmetry, irregular Border, multiple Colours, Diameter >6 mm, Evolving. Nodular and amelanotic subtypes can be skin-coloured or pink — see our guide on when to worry about a mole.
The behavioural test
When clinical features are ambiguous, behaviour decides:
- Stable for years → almost always benign.
- Slowly growing or changing → see a dermatologist within 4 weeks.
- Rapid change in 4–8 weeks → see a dermatologist within 2 weeks.
- Bleeds, crusts, or doesn't heal → urgent referral.
Reduce future damage starting today
- Daily SPF 30+ even in winter — UVA penetrates clouds and windows
- Reapply every 2 hours when outdoors, sooner if swimming or sweating
- Wide-brimmed hat and UPF clothing for prolonged outdoor activity
- Avoid sunbeds — they triple melanoma risk and accelerate ageing
- Use a topical retinoid 3–5x weekly to repair existing photodamage
- Vitamin C serum every morning under sunscreen for added antioxidant protection
Same-week dermatology referral if:
- A pearly bump on your face has been there for 4+ weeks
- A scaly patch is persistent, growing, or bleeding
- A pigmented lesion is changing, asymmetric, or has multiple colours
- An "ulcer" or "scab" hasn't healed in 6 weeks
- You have many actinic keratoses (field damage warrants treatment, not just observation)
How AI helps you decide
Free AI skin analysis is excellent triage for "is this normal?" questions. It distinguishes pigmented from non-pigmented lesions, applies ABCDE/EFG criteria, and flags the high-risk visual features dermatologists look for. It's not a substitute for biopsy — but it's a fast, free second opinion that saves you weeks of anxiety or, conversely, prompts you to make the appointment you'd otherwise put off.
Get an instant AI assessment
Free 60-second photo analysis distinguishes sun spots, actinic keratoses and skin cancer.
Frequently Asked Questions
Dr. Celina Kazumi Iwasa
VerifiedGMC-Registered · UK Hospital + Private Practice · Skin Cancer Screening Specialist
Dr. Iwasa is a GMC-registered dermatologist working across UK hospital and private practice settings. She specialises in skin cancer screening, mole assessment and dermoscopy, with a focus on UK and European patients across Fitzpatrick I–IV skin types.