When people search for melanoma on nail images, they are often trying to determine whether a dark streak or mark beneath a fingernail or toenail could be melanoma. Melanoma of the nail, also known as subungual melanoma, is a rare but potentially serious type of skin cancer that develops within the nail unit. It often resembles a bruise, fungal nail infection or harmless pigmentation, so many people overlook it during its early stages.
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What is Melanoma of the Nail?
Melanoma of the nail, also known as subungual melanoma, develops from melanocytes, the cells that produce pigment within the nail matrix. The nail matrix sits beneath the cuticle and produces the nail plate.
Although this form of melanoma accounts for only a small proportion of all melanoma diagnoses, many people find it difficult to recognise. Unlike many other types of melanoma, this form of skin cancer does not have a strong link to sun exposure. It can affect people of any skin type and often develops without an obvious cause.
The condition most commonly affects a single nail, particularly the thumb or big toe, but any nail can be affected whether it’s on the hands or the feet, and usually develops during later adulthood. However, it can occur in people of any age, ethnicity or medical history.
What Does Melanoma Under the Nail Look Like?
One of the most common questions people ask is, “What does melanoma under nail look like?” No single feature confirms the diagnosis, but several warning signs can indicate the need for further assessment.
A melanoma fingernail often develops as a single dark streak that gradually changes in width, colour or shape over time. This streak is often brown, black or dark grey and usually affects just one nail. As the condition progresses, the band may gradually become wider, become darker or develop irregular borders. In some cases, the pigment spreads onto the surrounding skin. Doctors refer to this as Hutchinson’s sign, and they consider it an important indicator of melanoma. The nail itself may also begin to change. It can:
- Become brittle
- Split
- Lift away from the nail bed
- Develop an uneven shape
- Less commonly, produce very little pigment and may appear pink, red or flesh-coloured, making it even more difficult to distinguish from other nail disorders. If the nail looks altered or damaged, it’s worth getting checked out.
Many people compare their symptoms with melanoma on nail images before seeking medical advice. Although melanoma on nail images internet searches can help you recognise the typical appearance of the condition, they cannot diagnose a cancerous nail change. Bruising, fungal infections and harmless pigmented streaks can sometimes resemble melanoma. For this reason, any persistent, new or changing abnormality should be assessed by a dermatologist rather than assuming it is harmless.
Nail Melanoma vs a Bruised Nail
Many people delay seeking medical advice because they believe the dark mark is simply a bruise caused by minor trauma.
A bruised nail usually develops after an injury and gradually moves towards the tip of the nail as it grows, eventually disappearing over several weeks or months. A melanoma fingernail behaves differently. It often develops without any obvious injury and remains attached to the base of the nail. Rather than growing out with the nail, it may slowly widen or darken over time.
Pigment spreading onto the surrounding skin, nail distortion or a streak that continues to change over several months may all indicate melanoma rather than a bruise.
Although many people compare their symptoms with melanoma on nail images, these images cannot replace a clinical examination. If you notice a new dark streak, particularly if it affects only one nail or continues to change in appearance, seek expert assessment rather than waiting to see if it improves. 
What Causes Nail Melanoma and Who is at Risk?
Like other forms of melanoma, subungual melanoma develops when pigment-producing cells begin to grow uncontrollably within the nail matrix. Unlike many other forms of skin cancer, ultraviolet (UV) exposure does not primarily cause this condition. Instead, researchers believe genetic changes within the pigment-producing cells of the nail matrix allow these cells to grow uncontrollably.
Although anyone can develop nail melanoma, several factors may increase the risk. These include:
- Increasing age
- Personal or family history of melanoma and
- Previous injury to the nail (Although trauma does not directly cause melanoma, it may draw attention to an existing abnormality that might otherwise go unnoticed)
Nail melanoma can affect people of any ethnicity or skin type, but it accounts for a higher proportion of melanoma diagnoses in people with darker skin tones than many other forms of skin cancer. It almost always affects a single nail, most commonly the thumb or big toe. If a new dark streak develops in one nail and continues to change over time, a dermatologist should assess it. 
When Should You See a Dermatologist?
Most nail abnormalities are harmless, but some changes should never be ignored. You should arrange a professional assessment if you notice:
- A new dark streak developing in one fingernail or toenail.
- A stripe that becomes wider, darker or changes in shape.
- Uneven colouring or blurred borders.
- Pigment extending onto the surrounding skin.
- Persistent splitting, thickening or distortion of the nail.
- Bleeding, ulceration or a sore that does not heal.
- A pigmented streak that does not grow out with the nail over time.
These features do not necessarily mean you have melanoma, but they do warrant further investigation to exclude subungual melanoma or another serious underlying cause. Even if the change turns out to be benign, an assessment can provide reassurance and ensure that any necessary treatment is not delayed.
How is Nail Melanoma Diagnosed?
Assessment begins with a detailed consultation. If you have a suspected melanoma fingernail, your dermatologist will ask when the change first appeared and whether it has altered over time. Your dermatologist will ask if:
- It has altered over time
- There has been any previous injury
- You have a personal or family history of melanoma or other skin cancers
The dermatologist examines the nail using dermoscopy, a specialised magnifying device. This enables them to assess subtle pigment patterns beneath the nail in far greater detail than the naked eye allows. They may also take clinical photographs if they need to monitor the lesion over time.
Dermatologists can distinguish melanoma under nail from more common conditions such as:
- Bruising
- Fungal nail infections
- Benign pigmented streaks
If your dermatologist suspects subungual melanoma, they may recommend a biopsy of the nail matrix or nail bed. This is the only way to confirm the diagnosis and determine whether cancer cells are present.
How is Nail Melanoma Treated?
The stage of the melanoma determines the most appropriate treatment. When doctors diagnose the cancer early and before it spreads beyond the nail unit, they usually recommend surgery. Their aim is to remove the melanoma completely while preserving as much healthy tissue as possible.
Treatment may include:
- Surgical removal of the melanoma.
- Removal of part or all of the nail unit.
- A sentinel lymph node biopsy to check whether the melanoma has spread.
- Additional treatments, such as immunotherapy or targeted therapy, for more advanced disease.
Your specialist will recommend a treatment plan based on several factors, including the thickness of the melanoma, whether it has spread and your general health. They will tailor the treatment plan to your individual needs following a thorough assessment.
Doctors achieve much better outcomes when they diagnose melanoma early. Seeking prompt assessment for any suspicious nail change gives you the best opportunity for early treatment. Early diagnosis also provides more treatment options and improves long-term outcomes. 
Can Nail Melanoma Be Prevented?
Unlike many other types of skin cancer, sun exposure does not play a major role in causing nail melanoma, so no one can guarantee prevention. However, you can become familiar with the appearance of your nails and spot unusual changes at an earlier stage, when treatment is often simpler and more effective. Simple steps include:
- Examining your fingernails and toenails regularly.
- Removing nail polish or gel polish occasionally so you can inspect the natural nail.
- Taking photographs of any unusual pigmentation to monitor for changes.
- Seeking medical advice if a dark streak appears or changes in appearance.
- Attending regular skin examinations if you have previously been diagnosed with melanoma.
Most nail changes are harmless, but early assessment can help identify subungual melanoma before it becomes more advanced.
Frequently Asked Questions
Is Nail Melanoma Common?
No. Nail melanoma is rare and accounts for only a small percentage of all melanoma diagnoses. However, many people mistake it for more common nail conditions. Learn to recognise the warning signs and seek medical advice if you notice a persistent or changing abnormality.
Does Nail Melanoma Hurt?
In its early stages, nail melanoma is usually painless. As the condition progresses, some people may experience discomfort, bleeding, nail splitting or changes to the surrounding skin. The absence of pain does not mean a nail change is harmless, which is why any unexplained pigmentation should be assessed if it persists.
Can I Diagnose Melanoma from Online Images?
Many people search for melanoma on nail images when they notice a dark streak beneath a nail or suspect a melanoma fingernail. While photographs can help you understand the typical appearance of the condition, they cannot confirm a diagnosis. Bruising, fungal nail infections and harmless pigmented streaks can all look similar, particularly during the early stages. If you are concerned about melanoma under nail, a professional examination is the only reliable way to determine the cause.
Does Every Dark Line in a Nail Mean Melanoma?
No. Most dark streaks within the nail are caused by benign conditions, such as harmless pigmentation, previous injury or certain medications. However, not every melanoma fingernail begins with obvious symptoms, so any persistent or changing dark streak should be assessed promptly.
How to Book a Dermatology Consultation
Most nail changes are harmless, but some require specialist assessment. If you have noticed a new or changing dark streak beneath a fingernail or toenail, our consultant dermatologists can assess the cause and recommend any further investigation or treatment if needed. If you are concerned about melanoma of the nail or subungual melanoma, arrange a consultation with our team.