Adults typically carry dozens of moles, and the overwhelming majority will never cause a problem. The point of checking is not to catalogue every mark — it is to notice the small number that behave differently from the others.
Melanoma is far less common than other skin cancers but accounts for most skin cancer deaths, and it is highly treatable when caught early. Early detection is largely a matter of noticing change.
The features that matter
The long-standing checklist is still the most useful starting point.
- Asymmetry — one half does not match the other
- Border — edges that are ragged, notched or poorly defined rather than smooth
- Colour — more than one shade within a single lesion, or unusual colours
- Diameter — larger than about 6 mm, roughly a pencil eraser, though small melanomas exist
- Evolving — any change in size, shape, colour, or sensation
Of these, evolution is the one clinicians weight most heavily. A mole that has looked the same for twenty years is far less concerning than one that has changed over three months, whatever its appearance.
Other things worth showing someone
Not everything concerning is a mole.
- A sore or scab that has not healed within a month, or heals and reopens
- A new firm bump, particularly pearly or translucent, on sun-exposed skin
- A rough, scaly patch that persists and sometimes bleeds
- A dark streak appearing under a fingernail or toenail without an injury to explain it
- Any lesion that itches, bleeds, or is tender without cause
Who should be checking more carefully
Risk is not evenly distributed. Pay closer attention if you have fair skin that burns easily, a large number of moles, a history of blistering sunburns, a personal or family history of skin cancer, a history of tanning bed use, or a condition or medication that suppresses your immune system.
How to check yourself
Once a month, in good light, after a shower. Work through it in the same order each time so you do not skip areas: face and ears, scalp, neck, chest and torso, both sides of each arm and hand including under the nails, front and back of the legs, tops and soles of the feet and between the toes. Use a hand mirror or ask someone for your back, which is where a substantial share of melanomas in men are found.
Photographs help. A phone photo of anything you are unsure about, with a ruler or coin for scale, makes a three-month comparison genuinely meaningful rather than a memory test.
When to book
Anything that fits the checklist, anything that has changed, anything that has not healed in a month, or anything simply worrying you. A virtual dermatology assessment can review clear photographs, triage what needs direct examination, and arrange in-person assessment or biopsy where that is warranted. Nobody will think you wasted their time — the whole point of the system is that most checks are reassuring.
