Know Your Skin

The ABCDEF/G Guide

Use the ABCDEFG checklist — recommended by BPAC New Zealand — to check your own skin regularly:

Close-up of a mole or skin lesion with black and brown coloring on skin.
Close-up of a mole or skin lesion with black and brown coloring on skin.

A — Asymmetry
One half doesn't match the other

Close-up of a mole on human skin with the DermNet logo in the bottom left corner.

B — Border
Irregular, ragged, or blurred edges

Close-up image of a skin lesion with a dark, irregularly-shaped mole on light skin, with text overlay reading 'Te Whatu Ora, Health New Zealand.'
Close-up image of a skin lesion with a dark, irregularly-shaped mole on light skin, with text overlay reading 'Te Whatu Ora, Health New Zealand.'

C — Colour
More than one colour, or uneven colour

Close-up of a skin mole with dark pigmentation and irregular borders.
Close-up of a skin mole with dark pigmentation and irregular borders.

D — Different
Looks different from your other moles (‘ugly duckling’ sign)

Close-up photo of a mole or skin growth on human skin with hair follicles visible.

E — Evolving
Changing in size, shape, or colour over weeks to months

Close-up of skin with a small mole and a DermNet logo in the lower left corner.

F/G — EFG (Elevated, Firm, Growing)
Key warning signs for nodular melanoma — a rapidly growing raised, firm lump

Any lesion that is new, changing, or doesn't look right deserves a professional assessment.

Don't wait.

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Melanoma Under the Nails

One important and often overlooked form of melanoma is subungual melanoma — melanoma that develops under a fingernail or toenail. It is a subtype of acral lentiginous melanoma (ALM), a rare form of skin cancer that arises on the palms, soles, and nail beds — areas not typically associated with sun exposure.

Subungual melanoma most commonly appears as a dark brown or black vertical streak running along the nail — known as longitudinal melanonychia.

Close-up of an adult toenail with dark discoloration and thickening, possibly indicating a fungal infection, on a blue textured background with 'DermaNet' logo and slogan.

Because it is not linked to sun exposure and can be mistaken for a bruise, fungal infection, or trauma, diagnosis is often delayed.

At SkinSure, our full skin checks include assessment of the nails — because melanoma can hide in places you may not think to look.

If you notice a new dark streak on a single nail that is growing, widening, or changing — have it assessed promptly.

Other warning signs include:

  • A dark band in the nail that is widening or changing

  • Pigmentation spreading onto the skin surrounding the nail (known as Hutchinson's sign)

  • Nail dystrophy — brittleness, cracking, or thickening of the nail

  • Bleeding or ulceration under the nail

While subungual melanoma accounts for around 2–3% of melanoma cases in people with lighter skin, it represents a disproportionately high percentage — up to 30% — of melanomas diagnosed in people with darker skin tones, including those of Asian, African, and Pacific descent.

Because it is not linked to sun exposure and can be mistaken for a bruise, fungal infection, or trauma, diagnosis is often delayed.

At SkinSure, our full skin checks include assessment of the nails — because melanoma can hide in places you may not think to look.

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