A spot that appears waxy, raised or ‘stuck on’ may be a harmless seborrhoeic keratosis. But appearance alone is not enough to rule out melanoma. In the question of melanoma versus seborrhoeic keratosis, the safest answer is not a self-diagnosis – it is a timely examination by a qualified health professional.

Australia has some of the highest rates of skin cancer in the world. Melanoma can grow quickly and spread if it is not found early, while seborrhoeic keratoses do not become melanoma and usually need no treatment. Knowing the broad differences can help you recognise when a spot deserves urgent attention. Knowledge can save your life, but a skin check provides the answer.

What is a seborrhoeic keratosis?

A seborrhoeic keratosis is a common benign skin growth. They become more frequent with age and can occur almost anywhere except the palms and soles. Some people develop one or two, while others develop many over time.

They often look as though they have been placed on top of the skin. Their surface may be waxy, rough, crumbly or warty. Colours range from skin-coloured and light tan to dark brown or nearly black. They may be flat or raised, and can become itchy or irritated when rubbed by clothing, jewellery or a razor.

Despite the name, seborrhoeic keratoses are not caused by poor hygiene and are not contagious. They are benign, meaning they are not cancer. A doctor may remove one if it catches, bleeds because it is repeatedly irritated, or causes discomfort or concern.

What is melanoma?

Melanoma is a cancer of melanocytes, the cells that produce pigment in the skin. It can develop within an existing mole, but many melanomas begin as a new spot. It may occur on skin that gets regular sun exposure, such as the back, legs, face, ears and arms, but it can also develop in less obvious places including the scalp, nails, soles of the feet and genital area.

Melanoma does not always look like the textbook dark, irregular mole. It can be brown, black, pink, red, purple, skin-coloured or a mixture of colours. Some melanomas are raised; others are flat. This variation is one reason a changing or unusual lesion should not be dismissed because it does not match an image found online.

Melanoma versus seborrhoeic keratosis: the visible clues

There is overlap between these lesions. A seborrhoeic keratosis can be dark, uneven and crusty. Some melanomas can look raised, scaly or wart-like. Even experienced clinicians may use dermoscopy, a specialised magnified skin examination, to assess a suspicious spot. If there is doubt, a biopsy is the only way to confirm the diagnosis.

Still, certain patterns should prompt a skin check. Seborrhoeic keratoses commonly have a sharply defined, stuck-on appearance and may have tiny surface pits or a waxy texture. They often remain broadly similar over time, although they can slowly become thicker or darker.

Melanoma is more likely to stand out as a lesion that is new, changing or clearly different from the others on your skin. This is often called the “ugly duckling” sign. If one spot does not resemble your usual moles or age-related marks, it deserves attention.

The ABCDE guide can also be useful. Look for asymmetry, an irregular border, uneven colour, a diameter that is growing or larger than about 6 mm, and evolution – any change in size, shape, colour, surface or sensation. The most useful letter is E. Change is a warning sign, even when a lesion is small.

Do not rely on the absence of pain. Early melanoma is often painless. Itching, tenderness, bleeding, crusting or a sore that does not heal can all be reasons to seek assessment, but a lesion does not need to bleed before it is serious.

Why photographs and online comparison are not enough

Taking a clear photo can help you track a lesion between appointments, particularly if you include a ruler or familiar object for scale. It cannot diagnose skin cancer. Lighting, camera settings and screen displays change how colour appears, while surface detail can be missed entirely.

Online images also tend to show classic examples. Real skin lesions are less tidy. Melanoma may imitate a harmless growth, and a harmless growth may look alarming. This is particularly relevant for people with many moles, extensive sun damage, fair skin, a personal or family history of melanoma, or a history of frequent sunburn.

People with skin of colour should also take changing lesions seriously. Although melanoma is less common in darker skin, it can be diagnosed later and may occur in areas with little sun exposure, including the palms, soles and under nails. A new dark streak in a nail, particularly one that widens or affects the surrounding skin, needs prompt medical review.

When to book a skin check

Book a skin check soon if you notice a new spot in adulthood that is growing, changing, unusually dark or unlike the others on your body. Arrange an urgent medical appointment if a lesion is bleeding without a clear injury, becomes persistently painful, develops a non-healing ulcer, or changes noticeably over weeks or months.

A clinician will ask when you first noticed the spot and whether it has changed. They may examine your whole skin surface, not only the lesion that brought you in. This matters because people often focus on one visible mark while another suspicious lesion is hiding on the back, scalp or back of the legs.

If the clinician considers melanoma possible, they may recommend an excision biopsy, where the lesion is removed and sent to a laboratory. This can feel worrying, but it is the appropriate next step when cancer needs to be excluded. Early-stage melanoma is often highly treatable, and every minute counts when a suspicious lesion is being assessed.

Do not try to remove a suspicious spot yourself

Over-the-counter freezing products, acids and home remedies are not suitable for a spot that has not been diagnosed. Attempting to burn, cut or freeze a lesion can cause infection and scarring, and may delay a proper diagnosis. It can also alter the lesion before a doctor has had the chance to assess it.

If a doctor has confirmed that a spot is a seborrhoeic keratosis, removal may still be an option for irritation or cosmetic reasons. The method depends on the location, size and texture of the lesion, as well as the risk of scarring or pigment change. That decision should follow diagnosis, not come before it.

Reduce future risk while staying alert

Sun protection cannot prevent every melanoma, but it reduces harmful ultraviolet exposure. Use broad-spectrum SPF50+ sunscreen correctly, wear protective clothing, a broad-brimmed hat and sunglasses, seek shade, and avoid deliberate tanning. Reapply sunscreen every two hours when outdoors, and more often after swimming, sweating or towel drying.

Make skin checks part of your routine. Check your face, scalp, torso, arms, legs, soles, nails and areas that are hard to see with the help of a partner or mirror. If a spot looks different, changes, or simply does not feel right, do not wait for certainty. Arrange a professional skin check and let a trained clinician decide what it is.