Skin cancer is the most common cancer in many countries. Melanoma is the most dangerous type because it can spread to other organs if not caught early; basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are far more common but generally less aggressive. Regular skin checks by a dermatologist — and monthly self-examination — are the cornerstones of early detection.
The ABCDE rule for suspicious moles
The ABCDE criteria are a clinical and self-examination tool for identifying features associated with melanoma. Any mole or pigmented lesion that matches one or more of these should be seen by a doctor promptly.
| Letter | Feature | Normal vs concerning |
|---|---|---|
| A — Asymmetry | Shape | Benign moles are symmetrical; melanoma is often asymmetric |
| B — Border | Edge regularity | Benign borders are smooth; melanoma borders are irregular, notched or ragged |
| C — Colour | Pigment variation | Benign moles are uniform; melanoma has multiple shades — brown, black, red, white, blue |
| D — Diameter | Size | Concern if > 6 mm, though melanoma can be smaller |
| E — Evolution | Change over time | Any change in size, shape, colour or symptom (itching, bleeding) warrants review |
Other types to know
- Basal cell carcinoma (BCC) — pearly or waxy bump, often with a rolled border; may have a central depression or ulcer; common on sun-exposed areas; rarely spreads
- Squamous cell carcinoma (SCC) — firm red nodule or rough scaly lesion; can ulcerate; more likely than BCC to spread if untreated
- Actinic keratosis — a pre-cancerous rough scaly patch on sun-exposed skin; can progress to SCC if left untreated
What happens at a skin check
A dermatologist performs a full-body skin examination, typically using a dermatoscope — a handheld illuminated magnifier that reveals subsurface features not visible to the naked eye. Any suspicious lesion is photographed and mapped. A biopsy (punch biopsy or excision) is taken from lesions that cannot be confidently categorised as benign.
Total-body photography — baseline photos of all moles — is used in high-risk patients to detect change over time. Digital dermoscopy systems allow precise comparison of individual lesions at each visit.
Who should screen and how often
Annual full-body skin checks are recommended for: people with a personal or close family history of melanoma; those with many moles (> 50), atypical moles or moles present since childhood; fair-skinned individuals with significant sun exposure history; people who have had repeated sunburns, particularly blistering burns in childhood; and immunosuppressed individuals.
For average-risk adults, self-examination monthly and a dermatology review every 2–3 years is a reasonable baseline. Those in high-UV environments or with extensive occupational sun exposure should check more frequently.
"Melanoma caught at Stage I has a 99% five-year survival rate. Caught at Stage IV, that falls below 30%. The check takes ten minutes."
Sara Nassereddin, Health Technology Writer, Looms