What Is Melanoma? Signs, Symptoms and When to See a Doctor

Melanoma is a type of skin cancer that can develop in normal-looking skin, an existing mole, or less visible areas such as the palms, soles, and beneath the nails. Warning signs include a new or changing lesion, uneven colour, irregular borders, unexplained bleeding, and a spot that looks different from other moles. Suspicious skin changes should be assessed by a doctor, as melanoma can only be confirmed through clinical examination and, when needed, a biopsy.

Melanoma is a form of cancer that begins in melanocytes - the cells that produce melanin, the pigment that gives colour to the skin, hair, and eyes. Although it is less common than basal cell carcinoma and squamous cell carcinoma, melanomacan behave more aggressively because its cells may invade deeper tissues and spread to other parts of the body.

Recognising melanoma signs and symptoms early can make a meaningful difference to treatment outcomes. A melanoma may appear as a new spot, develop within an existing mole, or occur in a location that receives little sun exposure, including the palms, soles, and beneath the nails. At the National Cancer Centre Singapore (NCCS), we assess melanoma according to its location, depth, stage, and molecular characteristics before recommending an individual care plan.

Key Takeaways

• Melanoma begins in pigment-producing melanocytes and can develop in normal-looking skin as well as within an existing mole.
• The ABCDE guide helps identify suspicious pigmented spots, but melanoma can also be small, evenly coloured, pink, or located beneath a nail.
• In Asian populations, acral melanoma affecting the palms, soles, and nail , is proportionally more common than it is in populations of European ancestry.
• A new or changing lesion, an unexplained dark nail streak, a spot that looks different from a person’s other moles, or a sore that does not heal should be medically assessed.
• Only a clinical examination and, when appropriate, a biopsy can determine whether a suspicious skin lesion is melanoma.

What Is Melanoma?

Melanocytes are found mainly in the outer layer of the skin, called the epidermis. Their principal function is to produce melanin, which helps protect skin cells from some of the damage caused by ultraviolet (UV) radiation.

Melanoma develops when genetic changes disrupt the normal mechanisms that regulate melanocyte growth and survival. As a result, these altered cells begin to proliferate uncontrollably, forming a malignant lesion.

At an early stage, melanoma may remain confined to the epidermis. This is known as melanoma in situ. If the cells grow through the epidermis and enter the deeper dermis, the melanoma becomes invasive. The dermis contains blood vessels and lymphatic channels through which may serve as pathways through which cancer cells can spread to other parts of the body.

Although melanoma is most commonly associated with skin cancer, melanocytes are also present in other parts of the body, meaning melanoma can arise in a variety of sites. These include the skin, the nail unit, mucosal tissues such as those lining the mouth or nasal passages, the genital or anorectal region, and the eye.

This article focuses primarily on cutaneous and acral melanoma, which are melanomas involving the skin, palms, soles, or nail units.

Where Can Melanoma Appear?

Melanoma can develop anywhere melanocytes are present. The locations that deserve attention differ between individuals and populations.

Sun-exposed skin

Cutaneous melanoma can appear on areas that regularly or intermittently receive UV exposure. This includes the face, scalp, neck, arms, back, and legs.

While men are more likely to develop cutaneous melanoma on the trunk (central part of body that connects the head, neck and limbs) and women on the legs, it is important to note that melanoma can occur at any site, and these patterns should not be treated as rules.

Intermittent intense UV exposure and episodes of sunburn are particularly relevant to some cutaneous melanomas.

Palms and soles

Acral melanoma arises on the palms, soles, or within the nail unit. It is not necessarily caused by UV exposure and can occur in people of any skin colour.

Melanoma is relatively uncommon in Singapore, but its distribution differs from that seen in Western populations. An acral melanoma may first look like:

• A flat brown or black patch on the sole
• An irregular mark that resembles a bruise
• A patch with several shades of brown, black, grey, red or blue
• A lesion that gradually increases in size
• A non-healing area initially mistaken for a blister, corn or wart

A new mark on the foot that does not resolve as expected deserves medical attention, particularly if it grows, changes, or bleeds.

Beneath the fingernails or toenails

Nail melanoma, also called subungual melanoma, may appear as a brown or black line running lengthways along the nail. Pigmented nail streaks have several possible causes and are not automatically cancerous.

Features that should raise concern include:

• A new streak affecting one nail
• A band that becomes wider or darker
• Uneven colour within the streak
• Irregular or blurred borders
• Pigment extending onto the skin beside the nail
• Splitting, lifting or distortion of the nail
• Bleeding or a persistent lump beneath the nail

Dark nail streaks can be normal in people with more deeply pigmented skin, especially when similar bands affect several nails. The pattern and any change over time matter. A doctor or dermatologist should assess a new or evolving streak rather than relying on photographs online.

What Are the Main Melanoma Signs and Symptoms?

Melanoma does not have one fixed appearance. A dark, irregular mole is a recognised presentation, but it is not the only one.

The most important warning signs are change and difference. A lesion that is evolving or looks unlike the rest of a person’s moles may deserve closer attention even if it does not meet every item in a checklist.

ABCDE Guide to Check a Mole or Pigmented Spot

The ABCDE guide provides a structured way to examine pigmented skin lesions. It is a screening aid, not a method of diagnosing melanoma at home.

“Evolving” is particularly important. A small lesion that is changing steadily may be more concerning than a larger mole that has remained stable for years.

Photographs taken under consistent lighting can help a person recognise change, but they should not delay a clinical assessment when a lesion already appears suspicious.

Look for the “Ugly Duckling” Sign

Most moles on one person tend to share certain features. They may be similar in colour, shape, or size even if they are not identical.

The “ugly duckling” sign describes a spot that looks noticeably different from the person’s other moles. It might be darker, lighter, larger, redder, or more irregular than the surrounding lesions.

This comparison can be useful because individual mole patterns vary. A dark mole may be expected on one person but stand out clearly on someone whose other moles are small and light brown.

A lesion can also be suspicious if it is the only new mole to appear or if it changes while neighbouring moles remain stable.

Melanoma May Not Be Brown or Black

An amelanotic melanoma contains little or no visible pigment. It may appear:

• Pink or red
• Flesh-coloured
• Pearly or translucent
• Like a small, raised lump
• Like an irritated patch or healing pimple
• As a sore that repeatedly crusts or bleeds

Because it lacks the dark colour commonly associated with melanoma, it may be mistaken for an insect bite, scar, eczema patch, or non-cancerous growth.

A pink or skin-coloured lesion that enlarges, changes, bleeds, or does not heal should be examined even if it does not resemble a traditional mole.

Other Changes That Should Not Be Ignored

The ABCDE guide does not capture every possible presentation. Other melanoma signs and symptoms can include:

• Itching or a new sensation within a mole
• Pain or tenderness
• Bleeding without an obvious injury
• Oozing or crusting
• A surface that becomes scaly
• A mole becoming firmer or more raised
• Redness or swelling beyond the lesion’s edge
• Breakdown of the skin
• A new lump beside an existing pigmented spot

Itching alone does not mean that a mole is melanoma. However, persistent itching or itching accompanied by visible changes to a mole warrants greater clinical concern.

When Should You See a Doctor?

You do not need to wait until a lesion meets all five ABCDE criteria. Arrange a medical assessment if you notice:

• A new pigmented or unusual-looking spot that continues to grow
• A mole changing in size, shape, colour or texture
• A spot that looks different from your other moles
• A dark patch on the palm or sole that does not fade
• A new or widening dark streak beneath one nail
• Pigment spreading from a nail onto the nearby skin
• A lesion that repeatedly bleeds, crusts or breaks open
• A sore that does not heal after several weeks
• A lump or patch that remains unexplained
• A mole that becomes persistently painful or itchy

Seek assessment sooner if the change is rapid or if you have previously had melanoma, have a strong family history of the disease or are immunosuppressed.

A general practitioner can perform an initial assessment and refer you to a dermatologist or another appropriate specialist. A doctor may use a dermatoscope, a handheld instrument that magnifies the skin and reveals structures not easily seen with the unaided eye.

Dermoscopy can improve assessment, but it does not always provide a final diagnosis. If melanoma is suspected, a tissue examination is usually required.

How to Perform a Useful Skin Self-Check

A self-check should be systematic so less visible areas are not missed. A full-length mirror, hand mirror, and good lighting can help.

Areas to examine:

• Face, ears, neck and scalp
• Chest, abdomen and sides of the body
• Front and back of both arms
• Hands, spaces between the fingers and fingernails
• Front, back and sides of both legs
• Feet, soles, spaces between the toes and toenails
• Back, buttocks and back of the neck using a second mirror
• Areas covered by underwear, where practical

Regular skin self-examination is recommended, ideally monthly. The goal is to become familiar with your normal pattern so that a new or changing lesion is easier to recognise.

What Increases the Risk of Melanoma?

A risk factor increases probability but does not determine what will happen to an individual. People with few recognised risk factors can still develop melanoma.

Ultraviolet radiation and sunburn

UV radiation can damage DNA in skin cells. Exposure comes from sunlight as well as artificial tanning devices.

Risk is influenced by the intensity and pattern of exposure, not only the total amount of time spent outdoors. Repeated sunburn, especially during childhood and adolescence, is associated with a higher melanoma risk later in life.

Acral and mucosal melanomas are not linked to UV exposure in the same way, so sun protection cannot prevent every melanoma.

Skin type and number of moles

People with lighter skin, hair, or eyes and those who burn easily have less natural protection against UV damage. Having numerous moles or atypical moles can also increase risk.

Darker skin contains more melanin, but it does not provide complete protection. Melanoma may also be detected later in people with darker skin because patients and healthcare providers may be less suspicious of skin cancer.

Personal or family history

Someone who has previously had melanoma has a greater risk of developing another primary melanoma. Risk may also be higher when a close blood relative has had the disease.

A strong family pattern can occasionally be associated with an inherited cancer predisposition. Genetic assessment is not needed for every melanoma patient, but it may be considered when several close relatives are affected or a person has developed multiple primary melanomas.

The provides genetic counselling to individuals with a personal and/or family history of cancer. If you have a personal or family history suspicious for a hereditary cause, call 6436 8088 for an appointment with CGS.

A weakened immune system

People with reduced immune function, including some organ transplant recipients and those taking long-term immunosuppressive medication, can have a higher risk of skin cancer.

These patients should follow the skin surveillance advice given by their care team and report suspicious changes promptly.

How Is Melanoma Confirmed?

A visual assessment can identify a suspicious lesion, but it cannot confirm melanoma. Diagnosis generally requires removal of all or part of the lesion so it can be examined by a pathologist.

When feasible, the doctor may perform an excision biopsy, removing the entire suspicious lesion with a small margin of surrounding normal-looking skin. The purpose at this stage is to establish the diagnosis and measure important features, not necessarily to complete all cancer surgery in one procedure.

The pathology report may include:

• The melanoma subtype
• Breslow thickness, which measures how deeply the melanoma has grown
• The presence or absence of ulceration
• The rate of cell division in selected reports
• Whether the biopsy edges contain melanoma cells
• Other microscopic features relevant to staging

Breslow thickness is a particularly important prognostic factor because the depth helps estimate the likelihood of spread and guides further management. Depending on the findings, additional surgery, lymph node assessment, imaging, or molecular testing may be considered.

A suspicious mole should not be burned, lasered, or destroyed without an appropriate diagnosis, as this can prevent the tissue from being examined fully.

Can Melanoma Be Prevented?

Not every melanoma is preventable, particularly acral, mucosal, ocular, or genetically influenced melanoma. Nevertheless, reducing unnecessary UV exposure remains one of the most effective steps in lowering the risk of UV-related skin cancers.

It is recommended using at least SPF 50 sunscreen with broad UVA protection and reapplying it every two hours during prolonged outdoor exposure. Sunscreen should be used together with shade and protective clothing, not as permission to remain in intense sunlight for longer.

Practical measures include:

• Seeking shade during periods of intense sunlight
• Wearing long sleeves, a broad-brimmed hat and UV-protective sunglasses
• Using a broad-spectrum sunscreen with strong UVA and UVB protection
• Applying enough sunscreen to exposed skin
• Reapplying sunscreen after sweating, swimming or prolonged outdoor activity
• Avoiding tanning beds and artificial tanning devices
• Protecting children from sunburn
• Checking the palms, soles and nails as well as sun-exposed skin

Recognising Melanoma Signs and Symptoms Can Can Make a Difference

Melanoma may look like an irregular dark mole, but it can also appear as a pink lump, a changing patch on the sole, or a dark streak beneath a nail. The most useful warning signs are a lesion that is new, evolving, non-healing, or visibly different from the rest of the skin.

Most moles and pigmented marks are benign. Still, it is safer to have a concerning change assessed than to monitor it indefinitely without medical guidance. Photographs and self-checks can help identify change, but they cannot replace clinical examination and biopsy when melanoma is suspected.

The earlier a melanoma is identified, the more treatment options are available, and the better the likely outcome. If you notice possible melanoma signs and symptoms, consult a doctor for an appropriate assessment. If melanoma is diagnosed, our multidisciplinary teams at NCCS evaluate its depth, stage, location, and biological characteristics before recommending care. Learn more about the personalisedcancer treatment and support available at NCCS.

Frequently Asked Questions

1. Can melanoma spread after a mole is biopsied?
   A properly performed biopsy does not cause melanoma to spread. It provides the tissue needed to make an accurate diagnosis and determine important features such as tumour depth. Delaying a recommended biopsy may allow an existing melanoma to continue growing.
   
   
2. Is melanoma contagious?
   No. Melanoma cannot be transmitted through touch, shared personal items, sexual contact, or close contact with someone who has the disease.
   
   
3. Can a tattoo hide melanoma?
   Yes, dark or densely coloured tattoo ink can make a new or changing lesion more difficult to notice. A mole should not be tattooed over, and any suspicious change within or beside a tattoo should be assessed.
   
   
4. Can children develop melanoma?
   Melanoma can occur in children, but it is rare. A rapidly changing mole, unexplained bleeding lesion, or unusual growth should still be examined. Changes that occur naturally as a child grows can complicate assessment, so a doctor should evaluate concerning lesions.
   
   
5. Does removing a normal mole prevent melanoma?
   Removing an ordinary benign mole does not generally prevent melanoma because the disease can arise in normal-looking skin. Mole removal may be recommended when a lesion is suspicious, repeatedly irritated, or difficult to monitor, but preventive removal of every mole is neither practical nor necessary.