Dermatology
Melanoma & Skin Cancer
Library·Dermatology·Melanoma & skin cancer
Don't miss
- Acral lentiginous melanoma - palms, soles, subungual - disproportionate in Maori and Pacific, not UV-related
- Nodular melanoma - lacks ABCDE features; use EFG (Elevated, Firm, Growing)
- Amelanotic melanoma - rapidly growing pink/red nodule
- Non-healing ulcer or "spot that bleeds" on sun-exposed skin (SCC)
First-line
- Screen
- ABCDE + ugly duckling. Add EFG for nodular
- If uncertain
- Excise with 2 mm margin for diagnostic histology - do NOT watch and wait
- High-risk surveillance
- Annual full-skin check: prior melanoma, FDR family history, multiple atypical naevi, heavy UV history
- Sun protection
- SunSmart - shade, clothing, hat, SPF 30+ broad-spectrum, sunglasses
Refer when
- Suspicious lesion you are not excising yourself - urgent (2-week) dermatology / plastics
- Confirmed melanoma - wide local excision planning
- Lesions in difficult sites (face, ear, hands, genitals)
- Multiple atypical naevi or strong family history - dermatology surveillance
Tell the patient
- NZ has among the highest melanoma rates in the world - early detection saves lives
- Take photos of moles you are watching - small changes are easy to miss
- Sun protection still matters every day from September to April
- Skin cancer is treatable when caught early - come back rather than wait
Melanoma is New Zealand's most dangerous skin cancer and the country has one of the highest per-capita incidence rates in the world, driven by high ambient UV, outdoor culture, and a predominantly fair-skinned population. Non-melanoma skin cancer (basal cell carcinoma and squamous cell carcinoma) is far more common but less likely to be fatal; both warrant prompt recognition and appropriate management in primary care.
❍ Recognising melanoma: ABCDE and beyond
The ABCDE criteria provide a structured approach to pigmented lesions:
- Asymmetry: one half does not mirror the other
- Border: irregular, ragged, notched, or blurred edges
- Colour: variation within the lesion - shades of brown, black, red, white, or blue
- Diameter: greater than 6 mm, though early melanomas can be smaller
- Evolving: any change in size, shape, or colour, or a new symptom (bleeding, itching) over weeks to months
The ugly duckling sign - a lesion that simply looks different from a patient's other naevi - has comparable sensitivity to ABCDE and is particularly useful in patients with many moles, where individual lesion characteristics may be less distinctive.2
Dermoscopy significantly improves diagnostic accuracy and reduces unnecessary excisions in experienced hands. If you use it, specific features associated with melanoma include atypical pigment network, regression structures, blue-white veil, and atypical vasc