A spot that seems to have appeared out of nowhere can be unsettling, particularly after years of sun exposure. Can melanoma appear suddenly? It can certainly look that way. Some melanomas develop as a new mark on previously normal-looking skin, while others have been present but only become noticeable once they change in size, colour, shape or feel.
The practical message is simple: do not wait to see whether a suspicious new or changing spot settles on its own. Melanoma can spread if left untreated, but when it is found early, treatment is often much more straightforward. A timely skin check can provide answers and, where needed, urgent care.
Can melanoma appear suddenly, or was it already there?
Melanoma begins when pigment-producing skin cells, called melanocytes, grow in an abnormal and uncontrolled way. It may arise within an existing mole, but many melanomas develop as a completely new lesion. That is why checking only the moles you have had since childhood is not enough.
A melanoma may seem sudden for several reasons. It may be on an area you do not regularly see, such as the back, scalp, behind the ears, soles of the feet or the back of the legs. A small change may also become more obvious quickly once the lesion develops a darker area, irregular edge, crust or raised section.
Some melanomas do grow faster than others. Nodular melanoma, for example, can grow vertically into deeper layers of skin relatively quickly. It does not always follow the familiar picture of a flat, irregular brown mole. It may look like a firm, raised lump that is black, brown, red, pink or skin-coloured. It may bleed, crust or continue to grow over weeks.
That does not mean every new mark is melanoma. Skin tags, harmless moles, seborrhoeic keratoses, insect bites and irritated follicles can all appear or change. But it is not possible to reliably tell the difference from a photo, an online checklist or a quick glance in the mirror. A trained clinician may use dermoscopy, a specialised magnified skin examination, and arrange a biopsy if needed.
Changes that should prompt a skin check
The ABCDE guide remains a useful starting point for spotting concerning changes:
- A is for asymmetry: one half does not match the other.
- B is for border: the edges are irregular, blurred, scalloped or poorly defined.
- C is for colour: there is more than one colour, or a new dark, blue, red, white or pink area.
- D is for diameter: the spot is growing, particularly if it is larger than 6 mm. Smaller lesions can still be melanoma.
- E is for evolving: any change in size, shape, colour, surface or sensation.
The most useful warning sign is often evolution. A mole does not need to meet every ABCDE feature to deserve assessment. If it is changing, it needs attention.
Also watch for the “ugly duckling” sign. This means a spot that looks noticeably different from your other moles. It may be darker, paler, larger, more raised or simply unlike the rest. Your own pattern matters. Someone with many freckles or moles may have one lesion that stands out, even if it is not especially large.
Symptoms are another reason to act. Book a skin check if a spot itches persistently, is tender, bleeds without a clear injury, forms a recurring scab, becomes crusty or does not heal. A non-healing sore should never be ignored, especially on sun-exposed skin such as the face, ears, neck, scalp, forearms and lower legs.
Why speed matters in Australia
Australia has some of the highest rates of skin cancer in the world. High UV levels, outdoor work and recreation, and a lifetime of sun exposure all contribute to risk. UV damage is cumulative, so the sunburn you had decades ago can still matter now.
Melanoma is not limited to older Australians or people with fair skin. It can affect adults of any age and people of every skin tone. In darker skin, melanoma is sometimes diagnosed later because people may wrongly assume they are not at risk. Check the palms, soles, nails, genital area and inside the mouth as well as sun-exposed areas. A new dark streak in a nail, particularly one that widens or extends onto the surrounding skin, should be assessed promptly.
Certain factors increase risk: a personal history of melanoma or other skin cancers, a close family history of melanoma, many moles, atypical moles, fair skin that burns easily, red or blond hair, heavy sun exposure, a weakened immune system, and past use of tanning beds. However, melanoma can occur without any obvious risk factors.
For people who work outdoors, including tradies, farmers, fishers, landscapers and delivery workers, regular self-checks and professional skin checks are a practical part of health care. The same applies to regular beachgoers, runners, golfers, surfers and parents spending long hours outdoors with children.
What to do when you notice a suspicious spot
If a lesion is new and changing, contact a GP or a skin cancer clinic and ask for the earliest available appointment. Tell the receptionist that the spot is changing, bleeding, growing or concerning you. This helps the practice understand the level of urgency.
Take a clear photo in good light before your appointment, ideally with a ruler or familiar object nearby for scale. A photo is not a substitute for examination, but it can help document change. Avoid picking, scratching or trying to remove the spot yourself. Over-the-counter wart treatments and home remedies can irritate the skin and delay a correct diagnosis.
If the area is bleeding, apply gentle pressure with a clean dressing. If you have a rapidly growing dark or raised lesion, a sore that will not heal, or a spot changing over days to weeks, seek assessment promptly rather than waiting for your next routine check.
At the appointment, the clinician will ask when you first noticed the lesion and whether it has changed or caused symptoms. They may examine your whole skin surface, because finding one concerning lesion can be a reason to look for others. If melanoma is suspected, a biopsy is usually needed to confirm the diagnosis. This involves removing all or part of the lesion for laboratory testing.
Do not rely on a single self-check
Self-checking is valuable, but some areas are hard to inspect alone. Use a full-length mirror and a hand mirror for your back, buttocks, scalp and the backs of your legs. Ask a partner, family member or trusted friend to help check places you cannot easily see. If you have many moles, photographs taken over time may make change easier to identify.
A professional skin check is particularly worthwhile if you have a personal or family history of skin cancer, lots of moles, a previous severe sunburn, or regular occupational UV exposure. Your clinician can advise how often you should be checked based on your individual risk. There is no single interval that suits everyone.
Prevention still matters after a skin check
Finding a suspicious lesion early is vital, but reducing future UV exposure is equally important. In Australia, protect your skin whenever the UV Index is 3 or above. Seek shade, wear sun-protective clothing, a broad-brimmed hat and close-fitting sunglasses, and apply broad-spectrum SPF50+ sunscreen generously to exposed skin. Reapply it at least every two hours, and after swimming, sweating or towel drying.
Sunscreen is one layer of protection, not a reason to stay in direct sun longer. Shade, clothing and planning outdoor activities outside peak UV periods provide stronger protection.
A new or changing spot may turn out to be harmless. Getting it checked is not overreacting – it is a sensible response to a disease where early detection can save your life. If something on your skin is different, changing or simply does not feel right, make the appointment. Every minute counts.