Melanoma is a skin cancer that starts in the cells that make pigment. It is much less common than other skin cancers but causes most skin cancer deaths, because it can spread. Found and removed while it is still thin, it is usually curable. A seborrheic keratosis is a common, harmless growth that looks stuck onto the skin, like a piece of wax or a small barnacle. They are not cancer and they do not become cancer. The reason to see a doctor is to be sure that is what you are looking at.
The same eight facts on every condition comparison.
It is a pigment-cell cancer.
Melanoma arises from melanocytes, the cells that produce pigment.
It can look many ways.
It may be dark, multicolored, pink or almost unpigmented.
Early assessment matters.
Invasive melanoma can spread beyond the skin.
Uncertain spots should not be removed at home.
Biopsy, not cosmetic removal, is the right step.
It is a benign growth.
Surface skin cells form a waxy, warty or stuck-on growth.
Color varies.
It can be tan, brown, gray or almost black.
It is not a precancer.
These growths become more common with age.
Uncertain lesions are tested.
Tissue is examined before any destructive treatment if the appearance is unclear.
Superficial spreading melanoma The most common, a growing flat spot.
Nodular melanoma A fast-growing raised bump.
Lentigo maligna melanoma Slow, flat brown patch on sun-damaged skin.
Acral lentiginous melanoma On palms, soles or under nails.
Classic seborrheic keratosis Raised, waxy, stuck-on growth.
Stucco keratosis Small white-gray bumps on the legs.
Dermatosis papulosa nigra Small dark bumps on the face.
Abnormal pigment cells escape normal growth controls and multiply within the skin. Some melanomas grow into deeper tissue, and the depth of invasion helps determine their stage.
A benign overgrowth of surface skin cells creates a localized plaque. Keratin and sometimes pigment collect in the growth, giving it a waxy, rough or stuck-on appearance.
Melanoma. More common in adults, but a concerning changing lesion needs assessment at any age.
Seborrheic Keratosis. Usually appears in adult life and becomes increasingly common with age.
Melanoma starts when pigment cells develop DNA damage and grow out of control. Ultraviolet light is the main cause of that damage for most melanomas.
Seborrheic keratoses are harmless growths of skin cells that become more common with age.
About 1 in 10 people with melanoma have a family history of it. Genes such as CDKN2A raise the risk.
They often run in families.
Evidence labels come from each condition’s own treatment list.
A strong urea cream can soften and flatten the rough white growths that scatter over the lower legs, called stucco keratoses, if the roughness is what bothers you. It smooths the surface rather than removing the growth, and it has to be used continuously. It does nothing for thick, dark, stuck-on growths elsewhere.
Wart treatments are often tried on these because the surface looks similar. Salicylic acid can thin the rough top layer, but it does not clear the growth, and it irritates the normal skin around it. The bigger problem is that it is usually being used on something nobody has examined.
This is aftercare, not treatment. A thin layer of plain petroleum jelly over a treated spot keeps the scab soft and gives the neatest healing, under a small dressing rather than an adhesive strip. It does nothing to a growth that is still there.
Daily mineral sunscreen over a spot that has just been treated stops the temporary mark from darkening and helps it fade faster, which matters most on the face, chest and hands. It will not remove a growth or stop new ones forming. Sun is only one of several things that drive these, and age and family history matter more.
A high-strength peroxide solution applied in clinic was approved for raised growths on the face and body. It cleared some growths, often needed repeat visits, and commonly caused stinging, crusting and pigment change. It was withdrawn from sale in the United States, so in practice removal is done by hand rather than with a liquid.
The treatment that cures the great majority of thin melanomas. Once the diagnosis is confirmed, a second and wider operation removes a margin of surrounding skin, with the width set by how thick the melanoma was. The scar is longer than most people expect, and that is the trade that stops it coming back at the site. Anything pigmented that is removed, anywhere, should be sent for pathology.
Above a certain thickness, the first lymph node the area drains to is located with a tracer and removed to see whether cells have reached it. It is a staging test rather than a treatment: it tells you where you stand and shapes what is offered next. It carries its own risks, including lasting swelling of the limb, so it is offered as a discussion rather than an automatic step.
Used at some centers for lentigo maligna on the face, where sparing skin matters and the true edge of the pigment is hard to see. It is not the standard operation for melanoma generally — wide excision is, and the evidence sits with that. If Mohs is offered to you, it is fair to ask why it suits this particular lesion in this particular place.
Nothing diagnoses melanoma except a biopsy. Where it is possible, the whole spot is removed with a narrow margin rather than sampled, because the pathologist needs the full depth to measure the thickness, and thickness sets everything that follows. It is done under local anesthetic and usually takes under half an hour. A biopsy does not make melanoma spread, and believing that it does is a common cause of delay.
When a growth is changing, bleeding on its own, or simply looks unlike your others, part or all of it is taken after numbing and examined under a microscope. It is the only way to be certain, and the threshold for doing it is deliberately low, because the cost of a small biopsy is trivial next to missing a melanoma. An irritated growth is one of the commonest reasons a benign growth ends up being sampled.
The growth is numbed and shaved off level with the skin in a few seconds. It is the method of choice when there is any question about what a growth is, because it produces tissue that can be sent to the laboratory. It leaves a flat mark that fades over months, and it does not stop new growths appearing elsewhere.
The growth is scraped off with a small curette and the base sealed with a fine electric tip. It is controlled and shallow, which is why it is often preferred for small facial growths and for the dark facial growths common on deeper skin tones. Scraping first still gives tissue that can be examined if there is doubt.
A few seconds of liquid nitrogen makes flatter growths blister and lift off over a week or two, and it is the quickest way to treat several at once. It destroys the growth, so nothing can be examined afterward, which is why it is not used on anything with a question attached. It is used cautiously on the face and on deeper skin tones, because the pigment cells are sensitive to cold and it can leave a pale spot.
An ablative laser can vaporise a growth precisely and is sometimes used when several need treating on the face. Like freezing, it destroys the tissue, so it is only for growths already confirmed as harmless. It is the most expensive of the options and it is not better than a curette for a single growth.
Melanoma does not progress on a fixed schedule. Some variants change over years, others over weeks, so this is the sequence, not a timetable. Skin checks continue for years after treatment, because a second melanoma and a recurrence are both possible, and close relatives are usually advised to have their skin checked.
Seborrheic keratoses appear slowly, change slowly, then stay. Two departures deserve attention: one growth that starts changing - growing, darkening, bleeding on its own, or itching persistently - and a sudden crop of many new ones over weeks to months.
Cells travel to the nearest nodes first
A lump near a previous melanoma site is significant and checked promptly.
Treated by an oncology team
Melanoma can spread to organs far from the skin. Immunotherapy and targeted therapy have changed outcomes substantially in the last decade.
Catching on clothing makes it flare
A growth caught by clothing, a strap or a waistband can turn red, swollen, itchy, crusted or sore, and can bleed. That is an irritated seborrheic keratosis. It settles, but it looks alarming and often prompts removal or a sample.
Arrange prompt assessment of a new or changing unusual spot, especially an evolving lesion or one that bleeds. Diagnosis requires clinical evaluation and usually biopsy.
Have a new, changing, bleeding or uncertain growth assessed; skin cancer can sometimes resemble a harmless stuck-on growth.
It varies more than people expect. The common superficial spreading variant often changes over months to a few years. Nodular melanoma can grow downward over weeks to a few months. You cannot tell which you have by looking, so a changing spot gets examined now, not in six months.
No, and this belief causes delay. Removing a suspicious lesion is how melanoma is diagnosed and how the thickness is measured, and thickness determines the treatment. There is no evidence a biopsy spreads it.
No. Most melanomas arise as new spots, so removing moles does not remove the risk and means many scars for no benefit. Many or unusual moles are a reason for regular examinations, not preventive removal.
Usually not. Pigmented nail bands are common and often normal in deeper skin tones, frequently on several nails at once. It needs examining if it is on one nail only, if it is getting wider, if it has more than one shade, if the nail is splitting, or if the pigment spreads onto the skin around it.
The melanoma is treated, but you are not discharged. Having had one raises the chance of a second, so skin checks continue for years, and close relatives are usually advised to have their skin examined. Ask how often yours should be and who arranges it.
Yes. Sun exposure raises risk, but melanoma also occurs on soles, palms, under nails and on skin never exposed, and in people who have never burned. Sun history changes your risk profile, not whether a particular spot should be looked at.
It could be, which is why it should be looked at rather than diagnosed at home. Melanoma is sometimes mistaken for a seborrheic keratosis, and a dermatoscope resolves most of these in seconds. The concerning features are change in size, shape or color, bleeding without being knocked, an irregular edge, and a growth unlike your others. Book rather than watch.
Age and family history account for nearly all of it. They accumulate steadily from the forties onward, and someone whose parents had many will develop many. A genuinely sudden crop over weeks to months, especially with itching, is different and worth examining.
No. Removal deals with that growth, not the age and inherited tendency behind it, so new ones can keep appearing elsewhere. That is expected, not a failed removal.
Often, at least for a while. A flat spot darker or paler than nearby skin is common, and dark marks usually fade over months. Pale marks can be permanent and are more noticeable on deeper skin tones, so ask about the method and do a test spot before treating a large area. Daily sunscreen on the treated spot makes a real difference.
Most likely it caught on clothing, a strap or a razor and became an irritated seborrheic keratosis. They look far worse than they are and they settle. Still have it looked at - an irritated growth is one of the harder ones to be sure about by appearance, and a growth that bled with nothing catching it is a different question.
As many as you and your doctor think sensible, usually in sessions rather than all at once. It is normally considered cosmetic, so ask about cost first. On the face, and particularly on deeper skin tones, start with a small test area and see how it heals.
Sources
