Condition

Melanoma

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.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026

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Change is the signal, not size, not color, not whether it hurts. A spot that is new, or different from how it looked a few months ago, or different from all your other moles, is the one to have examined, and melanoma that hurts or bleeds is usually melanoma that has been there a while. Watching is not a plan, and I would rather look at fifty harmless moles than see one melanoma at the appointment after the one it should have been caught at. Melanoma also occurs in every skin tone and on palms, soles, under nails and on skin that has never seen the sun, so check those places too and say so specifically if a spot there is changing.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

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How commonAround 100,000 new invasive cases are diagnosed in the United States each year. It is a small fraction of all skin cancers but causes the majority of skin cancer deaths
Who gets itAny age and any skin tone. Risk rises with fair skin, many moles, sunburns, tanning bed use, family history, immune suppression and age
Curable or managedUsually curable when it is found and removed while still thin. Once it has spread it is treated rather than reliably cured, although treatment has improved substantially
Prescription neededNot applicable. Melanoma is diagnosed by biopsy and treated by surgery, with drug treatment from an oncologist for more advanced disease
Time to improveA biopsy result usually takes a few days to two weeks. Treatment is planned from that result, not from how the spot looks

What It Is

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Melanoma is a cancer of melanocytes, the pigment cells. They sit along the bottom of the outer layer of skin, so melanoma usually starts at the surface and is visible long before it causes symptoms.

Most melanomas appear as a new spot rather than inside a mole you have had for years, though a minority do arise in an existing mole. The advice to watch your moles misses the more common pattern: something new that does not look like anything else on you.

Melanoma grows in two phases. First it spreads sideways within the top layer of skin, where it cannot spread elsewhere in the body. Then, in most variants, it grows downward into the deeper skin. How far down it has grown, measured in millimeters and called the Breslow thickness, is the most important line in the pathology report. It drives how much skin is removed, whether lymph nodes are checked, and what follows.

The variants do not all look the same. Superficial spreading melanoma is the most common, the flat, irregular, multi-colored spot most descriptions are based on. Nodular melanoma is a firm, raised, often evenly colored bump that grows downward from the start over weeks to months, and the usual rules miss it. Lentigo maligna develops slowly over years on sun-damaged skin, usually on an older adult's face. Acral lentiginous melanoma occurs on the palms, soles and under the nails, and is the one most often diagnosed in people with deeper skin tones. Amelanotic melanoma has little or no pigment and looks pink, red or skin-colored, which is why a persistent pink bump that keeps growing deserves the same attention as a dark one.

Melanoma also occurs where most people never look: the scalp, between the toes, under a nail, the genital area, the mouth and the eye. Less common, and found late.

Symptoms

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A spot that is not staying still

Changing Mole

A mole that has changed in size, shape or color, or that looks different from every other mole on the body. Change over weeks to months matters more than how it looks on a single day. Any clearly changing mole should be seen.
Uneven edges, mixed shades

Irregular Border and Color

A spot with a ragged or blurred outline and more than one color in it, such as brown mixed with black, red, white or blue. Uneven halves are part of the same picture. Photographs taken months apart make this easier to judge.
Easily missed sites

On the Palms, Soles or Nails

A dark patch on a palm or sole, or a new brown-black band running the length of a nail, especially if it widens or the pigment spreads to the surrounding skin. These sites are more commonly affected in deeper skin tones. They are easy to overlook, so they deserve specific attention.

Where It Shows Up

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Back view of a whole body with red marks across the upper and middle back, both shoulders, the lower back and the back of the head.
The back in men
The back is the commonest site in men, and it is the one found late, because nobody looks at it. The scalp is the same problem for the same reason. Anyone checking their own skin needs a second person or a mirror for these two.
Front view of a whole body with red marks down both lower legs and thighs and on the face and neck.
The lower legs in women, and the head and neck in both
The lower legs are the commonest site in women. The head and neck are common in both, and in older adults especially. Melanoma can appear anywhere, including skin that has never seen the sun.
Front view of a whole body with red marks on both palms and fingers, on both soles and across the genital area.
Palms, soles, nails and the genital area
These are the sites that get missed, and they are also the ones that matter most on deeper skin tones, where melanoma turns up on the palms, the soles, between the toes and under a nail far more often than anywhere sun-exposed. A dark streak under a nail that is widening should be looked at.

What Happens in the Skin

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This is what is going wrong under the skin, in the order it happens. Click a step to see it.

How Melanoma happens
Skin basics
BARRIEREPIDERMISDERMIS0NORMAL SKIN1ULTRAVIOLET LIGHT DAMAGES DNA2IT SPREADS SIDEWAYS AT FIRST3IT STARTS GROWING DOWNWARD4IT REACHES NODES AND ORGANS

Pigment cells sit in an even row along the bottom of the outer layer of skin. Sunlight damages the DNA inside them most days, and nearly all of that damage is repaired within hours. The cells stay in their row and divide only when they are told to.

Ultraviolet light, from the sun or a tanning bed, damages the DNA inside pigment cells. Almost all of that damage is repaired. Over years some of it is not, and a cell ends up with a set of mutations that let it multiply without the usual controls. Not every melanoma starts this way — the ones on palms, soles and nails largely do not.

The abnormal cell multiplies sideways within the top layer of skin. There are no blood vessels or lymphatic channels up here, so at this stage it cannot travel anywhere else in the body. This is the flat, irregular, multi-colored spot the ABCDE rules describe, and removing it at this point usually ends the story.

At some point cells begin growing down into the deeper skin, where the blood and lymphatic channels run. How far down it has gone, measured in millimetres as the Breslow thickness, is the single most important thing the pathology report says. Nodular melanoma skips most of the sideways phase and does this from the start, over weeks to months.

Once cells are in those channels they can travel to the nearest lymph nodes, and from there to organs such as the lungs, liver, bone and brain. This is the state everything on the lists below is pushing on. The only thing that decides whether a melanoma is caught before this step is how quickly a changing spot gets examined.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

Four things happen, and they explain why the same cancer behaves so differently depending on when it is found. Ultraviolet light, from the sun or a tanning bed, damages the DNA in pigment cells. Most damage is repaired, but over years some is not, and a cell picks up mutations that let it multiply uncontrolled. It first spreads sideways in the top layer of skin, where there are no blood vessels or lymphatic channels, so it cannot go anywhere. At some point it grows downward into the deeper skin, where those channels are, and cells can then travel to lymph nodes and other organs.

The pattern of exposure matters, not just the total. Intermittent intense exposure and blistering sunburns, especially in childhood, are linked more strongly to melanoma than steady daily exposure, which matters more for the other skin cancers. Tanning beds deliver exactly that, deliberately.

Not all melanoma is sun-driven. Melanomas on the palms, soles, under nails, in the mouth and in the genital area largely are not, and they occur in every skin tone. Sun history is not a screening tool, and a low-sun life is not a reason to skip examining a changing spot.

Genetics contribute in two ways: inherited risk, which shows up as melanoma in close relatives and sometimes in specific genes, and mutations acquired in the tumor itself. Some of those, such as BRAF mutations, matter for treatment, because drugs target them.

Risk Factors

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Risk factors change how closely you should be watched, not whether a particular spot needs examining. Plenty of melanomas occur in people with none.

Sun exposure
Ultraviolet exposure and sunburns
Blistering sunburns, especially in childhood, raise risk. Intense occasional exposure matters more than steady daily sun.
Sun exposure
Tanning beds
A recognized cause. Risk rises with more use and a younger age at first use.
Moles & past cancer
Many moles
A large number of moles, often quoted as more than about fifty, raises risk.
Moles & past cancer
Atypical moles
Large, irregular or unusually colored moles. They raise risk across all your skin, so the answer is regular checks, not removal.
Moles & past cancer
Previous melanoma or other skin cancer
One of the strongest predictors. A second is more likely, and usually found early because the person is followed.
Inherited
Fair skin that burns easily
With red or blond hair, light eyes and freckling. Risk markers, not requirements.
Inherited
Family history
Melanoma in a parent, sibling or child raises risk, and family clusters may prompt genetic assessment.
Inherited
Large congenital moles
Moles present from birth, especially large ones, carry a higher lifetime risk and are monitored.
Inherited
Rare inherited conditions
Xeroderma pigmentosum and some others cause very high risk and are managed by specialists.
Age & immune health
Age
Risk rises with age, but melanoma is also one of the more common cancers in young adults, so age never dismisses a changing spot.
Age & immune health
A weakened immune system
Transplant, some medicines and some illnesses raise risk and can make melanoma more aggressive. Ask about a skin check plan.

Course

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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.

In the top layer onlyIn situ
The stage everything on this page is aimed at

The abnormal cells sit in the outer layer only. It cannot spread from here, and removing it ends the story.

Growing sidewaysEarly invasive
Most people need nothing further

Cells have entered the deeper skin, but only just. Thin melanomas, generally under one millimeter, are removed with a margin of skin. Superficial spreading melanoma often changes over months to years.

Growing downwardThicker
Depth drives the next decision

The deeper the growth, the higher the chance cells have reached lymphatic channels. Thickness, and whether the surface has broken down, drive whether lymph nodes are checked. Nodular melanoma can grow downward over weeks to months, so a fast-growing firm bump is urgent whatever it looks like.

Reaching lymph nodesRegional
Cells travel to the nearest nodes first

A lump near a previous melanoma site is significant and checked promptly.

ArmpitGroinNeck
Reaching other organsAdvanced
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.

LungsLiverBoneBrain

What Makes It Better & Worse

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Melanoma is not one problem, it is four — DNA damage to pigment cells, sideways spread in the top layer, growth downward into deeper skin, and spread to lymph nodes and organs. Almost everything that decides the outcome happens between steps two and three, and where a melanoma is caught depends on how quickly it is examined.

What is driving yours?

FATBARRIEREPIDERMISDERMIS

Ultraviolet light, from the sun or a tanning bed, damages the DNA inside pigment cells. Almost all of that damage is repaired. Over years some of it is not, and a cell ends up with a set of mutations that let it multiply without the usual controls. Not every melanoma starts this way — the ones on palms, soles and nails largely do not.

The abnormal cell multiplies sideways within the top layer of skin. There are no blood vessels or lymphatic channels up here, so at this stage it cannot travel anywhere else in the body. This is the flat, irregular, multi-colored spot the ABCDE rules describe, and removing it at this point usually ends the story.

At some point cells begin growing down into the deeper skin, where the blood and lymphatic channels run. How far down it has gone, measured in millimetres as the Breslow thickness, is the single most important thing the pathology report says. Nodular melanoma skips most of the sideways phase and does this from the start, over weeks to months.

Once cells are in those channels they can travel to the nearest lymph nodes, and from there to organs such as the lungs, liver, bone and brain. This is the state everything on the lists below is pushing on. The only thing that decides whether a melanoma is caught before this step is how quickly a changing spot gets examined.

What helps

  • Daily sun protection, no tanning beds Cuts future risk, and you control it.

What makes it worse

  • Tanning beds A recognized cause, riskier the younger you start.
  • Blistering sunburns in childhood Linked more strongly than steady daily exposure.
  • Not telling close relatives It changes their screening advice.
  • Immune-suppressing treatment Risk is higher and behavior more aggressive.
  • Wearing sunscreen only on holiday Risk builds over a lifetime of ordinary days.

What helps

  • Learning the ABCDE signs Asymmetry, Border, Color, Diameter, Evolving above all.
  • The ugly duckling rule The mole that does not belong is worth examining.
  • Knowing ABCDE is not complete Firm, growing and new counts on its own.
  • Checking the places nobody checks Scalp, ears, soles, between the toes, nails, genitals and mouth.
  • Photographing your own skin Same distance and light, every few months.
  • Regular clinician skin checks Ask how often yours should be.
  • Dermoscopy A handheld magnifier, far more accurate than the naked eye.
  • A biopsy removing the whole lesion Lets the thickness be measured.

What helps

  • Surgical removal with a margin This cures most thin melanomas.

What makes it worse

  • Waiting out a changing spot A melanoma watched for six months is thicker.
  • Only checking sun-exposed areas The scalp, soles, nails and mouth are found late.
  • Assuming a pink bump is harmless Melanoma without pigment is a recognized variant.
  • A fast-growing bump ignored Nodular melanoma grows downward from the start.
  • Treating a spot at home Freezing kits and black salve destroy the evidence.
  • A mole lasered off cosmetically Destroy it and no one can check it.

What helps

  • Sentinel lymph node biopsy It changes staging and treatment.
  • Oncology referral for advanced disease Immunotherapy and targeted drugs changed the outlook.

What makes it worse

  • Skipping follow-up A second melanoma is meaningfully more likely.

How These Treatments Work

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Treatments for Melanoma do not all work in the same place. Tap one to see where it acts.

Pick a treatment
Skin basics
BARRIEREPIDERMISDERMISREMOVES IT WITH A MARGINCHECKS FOR SPREADTREATS SPREADBLOCKS THE GROWTH SIGNALPREVENTS THE NEXT ONE

How deep it has grown decides everything that follows.

Looks at the first lymph node it would travel to.

Trains the immune system to attack melanoma cells elsewhere in the body.

For tumors carrying a BRAF change.

Finding it early is the whole game, so regular checks matter more than any cream.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

Over-the-Counter Products

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Everything here you can buy without seeing anyone.

No over-the-counter options listed yet.

Prescriptions

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These need a prescription.

No prescription treatments listed yet.

Procedures

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These are done in the office, usually over several visits.

16:9 hero for Skin Biopsy. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Skin Biopsy works in the skin
Always
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.
16:9 hero for Surgical Excision. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Surgical Excision works in the skin
Always
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.
Sentinel lymph node biopsy
Strong evidence
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.
16:9 hero for Mohs Surgery. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Mohs Surgery works in the skin
Limited evidence
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.
Cryotherapy or cosmetic laser
Never use
Freezing or lasering a pigmented spot off destroys it without anyone ever finding out what it was. If it was a melanoma, the thickness can no longer be measured and no one can check the edges. A spot that concerns you is examined and sampled, not erased for convenience, and this is one of the few places where the cheaper, quicker option costs something real.

When to See a Dermatologist

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If a spot is changing, get it looked at, not after the summer and not to see whether it settles. Waiting is what separates an early melanoma from a late one. Book for any ABCDE sign: asymmetry, an uneven, notched or blurred border, more than one color in a single spot, a diameter larger than about six millimeters, and evolving, meaning changing in size, shape, color, height or surface, or newly itching, crusting or bleeding, which is the most important of the five. Book as well, letters or not, if a spot looks different from all your other moles, if a new firm bump is growing over weeks, if an unpigmented spot keeps enlarging, if a sore has not healed within four weeks, if a dark band in a nail is widening, or if a spot on a palm or sole is changing. Be seen urgently if a pigmented spot bleeds, ulcerates or grows fast. Dermoscopy helps, but only a biopsy diagnoses melanoma, so if you are told to watch a spot that is actively changing, ask for a biopsy or a second opinion. Anything pigmented that is removed goes to pathology, not off cosmetically.

— Dr. Schwarz, Board Certified Dermatologist

Complications

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Lookalikes

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Seborrheic Keratosis

The commonest thing mistaken for melanoma, in both directions. Seborrheic keratoses are harmless growths that can be dark brown or black with an irregular outline. They look stuck on rather than growing out of the skin, the surface is rough, waxy and crumbly, and people usually have several of a similar kind. A melanoma is flat or firm rather than crumbly, and it is normally the one spot that does not match the others. If you cannot tell them apart, that is exactly what dermoscopy is for.

Moles

Most dark spots are ordinary moles, and most melanomas turn up as new spots rather than as changes inside old moles. An ordinary mole is roughly symmetrical, one shade throughout, evenly edged, and it looks like your other moles. What matters is the one that does not belong, or the one that has changed over months. A mole that has looked the same for twenty years is not the one to worry about.

Basal Cell Carcinoma

A basal cell carcinoma that contains pigment can look like a dark raised melanoma, and both are skin cancers that need removing. The basal cell tends to be pearly and translucent with fine blood vessels running over the surface, often with a rolled edge or a central dip that bleeds and scabs over and over again. It grows slowly over years and does not spread to other organs. Either way the answer is the same: it is examined and sampled, not watched.

Myths

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  • "People with deeper skin tones do not get melanoma." They do. It is less common, diagnosed later, and outcomes are consistently worse, partly because of this belief. It also more often occurs on the palms, soles and under nails.
  • "If it does not hurt or bleed, it is not serious." Pain and bleeding are late features. Most melanomas are found because they changed, not because they caused a symptom. Waiting for a symptom is waiting for depth.
  • "Melanoma only happens where the sun hits." Much of it is sun-driven, not all. Melanoma occurs on the soles, between the toes, under nails, in the genital area, the mouth and the eye. Sun history is not a screening test.
  • "A mole I have had for years cannot become melanoma." Most melanomas are new spots, but existing moles can change, and a long-standing mole behaving differently is exactly what to have examined.
  • "All melanomas are dark." Amelanotic melanoma has little or no pigment and can look pink, red or skin-colored. A persistent pink bump that keeps growing needs examining like any dark irregular spot.
  • "A biopsy makes cancer spread." It does not, and this belief causes real delay. A biopsy is how melanoma is diagnosed, how thickness is measured, and how the right operation is chosen.
  • "A base tan protects you." A tan is visible DNA damage. It gives almost no protection, and the exposure used to get it adds risk.
  • "Sunscreen is more dangerous than the sun." Sunscreen is well studied and regulated, and ultraviolet radiation is a known cause of skin cancer. If an ingredient concerns you, mineral sunscreens, clothing, hats and shade all work.
  • "An app can tell me if my mole is fine." Phone apps and photo checkers cannot rule melanoma out, and a reassuring result is no reason to skip an appointment.

Questions Patients Ask

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How quickly does melanoma grow?

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.

Does having a mole removed spread cancer?

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.

Should I have all my moles removed to be safe?

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.

I have a dark line on my nail. Is that melanoma?

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.

If it is removed and the margins are clear, am I finished?

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.

I never sunbathe. Do I still need to worry about a changing spot?

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.

References

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