What Is Acral Lentiginous Melanoma?

Acral lentiginous melanoma (ALM) is the most common subtype of skin cancer that develops in the acral regions of the body, meaning the extremities.

The word "lentiginous" refers to a freckle-like, flat growth pattern that spreads along the surface of the skin before growing deeper. This makes early detection possible if you know what to look for.

These include:

• The palms of the hands
• The soles of the feet, including the bottom of the foot
• Under or around the fingernails and toenails
• Between the fingers and toes

Unlike most melanomas, acral lentiginous melanoma does not appear to be caused by sun exposure. This means anyone can develop it, regardless of skin tone or how much time they spend outdoors. In fact, it is the most common type of melanoma in people with darker skin tones, including people of African, Asian, and Hispanic descent.

When people think about skin cancer, they usually picture a mole on the back or face. But one of the most dangerous forms of melanoma can hide in plain sight on the palms of your hands, the soles of your feet, or under your toenails and fingernails.

Acral Lentiginous Melanoma Images 

Acral melanoma, and its most common form, Acral lentiginous melanoma cancer, is a type of skin cancer that affects areas not typically exposed to the sun. A rare but aggressive form of skin cancer that develops on the palms, soles or under nails. Because it grows in unusual locations. It is often missed or mistaken for a bruise, a fungal infection, or simply a dark patch of skin. By the time it is diagnosed, it can already be at an advanced stage.

At Sayyal Health, we believe that informed patients catch cancer early. This blog is about acral melanoma early warning signs and visual clues to diagnosis, treatment, and survival rates.

Causes and Risk Factors

The exact cause of acral melanoma is not fully understood. Because UV radiation does not appear to be the main driver, researchers believe other factors play a role.

Known Risk Factors

• Family history of melanoma or skin cancer
• Personal history of melanoma
• Chronic pressure or trauma to the feet (though this link is still being studied)
• Darker skin tone ALM accounts for a higher proportion of melanoma cases in people of colour
• Older age: in most cases, people are diagnosed in people over 60
• Weakened immune system

Important: Having none of these risk factors does not mean you are immune. Acral melanoma can affect anyone, which is why self-examination is so important.

What are the Early Signs and Acral Melanoma Symptoms?

One of the biggest challenges with acral lentiginous melanoma is that early signs can look completely harmless. People often dismiss them as a bruise, a stain, or a new freckle on the palm of their hand.

Here is what to watch for in each area:

Melanoma on the Palm of the Hand

Melanoma on the palm of the hand often appears as a flat, irregularly shaped patch of brown, black, or nail discoloration. Unlike a normal freckle on the palm of your hand, a melanoma lesion tends to:

• Have uneven, blurry, or jagged borders
• Slowly grow or change in size
• Show multiple shades of brown, tan, or black within the same patch
• Feel flat rather than raised in early stages

Melanoma on the Bottom of the Foot and Sole

Foot melanoma on the bottom of the foot or sole is particularly easy to overlook because most people do not routinely examine the undersides of their feet. Warning signs include:

• A new dark or discoloured patch on the sole
• Brown patches on the bottom of the feet that are irregular in shape or colour
• A lesion that is slowly spreading outward
• Any patch that bleeds, crusts, or does not heal

Melanoma on the Bottom of Foot and Sole Image

Melanoma Cancer Toenail and Fingernails

Nail melanoma, sometimes called 'melanoma cancer toenail', presents differently from skin lesions. It typically appears as the following:

• A dark brown or black vertical stripe running down the nail (called melanonychia)
• A stripe that is getting wider over time
• Darkening of the skin at the base of the nail (called Hutchinson's sign)
• A nail that is lifting, cracking, or deformed without a clear injury

It is important to note that dark nail stripes are common, and most are benign. However, any stripe that is widening, affecting multiple nails, or appearing for the first time in an adult should be evaluated by a doctor.

How Acral Lentiginous Looks on the Toe and Finger?

Acral lentiginous melanoma on a toe or acral lentiginous melanoma on a finger often first appears around the nail or on the skin of the digit. Moles in the palm or on the fingers that are irregular or changing should not be ignored.

Visual Clues: What Does It Look Like? (Including Dermoscopy)

When a dermatologist examines a suspicious lesion on the hands or feet, they often use a tool called a 'dermatoscope', a magnifying device that illuminates the skin. This technique is called dermoscopy.

Dermoscopy of Acral Melanoma

Dermoscopy acral lentiginous melanoma assessment looks for specific patterns under magnification. The most important finding is the parallel ridge pattern, one of the most reliable early signs of melanoma on acral skin. The pigmentation (dark colour) follows the ridges of the skin's fingerprint lines. In benign (non-cancerous) lesions, colour tends to follow the grooves, not the ridges.

Acral Melanoma Dermoscopy

Parallel ridge pattern Melanoma

Other dermoscopy acral melanoma warning signs include:

• Irregular diffuse pigmentation (colour spread unevenly across the lesion)
• Multiple shades of brown, grey, or black
• Irregular dots or globules scattered throughout
• A fibrillar pattern of fine lines running across the skin surface

Note: If you are ever shown an image of a lesion and the dark colour follows the ridges (the raised lines) of the sole or palm, this is a significant warning sign that requires urgent medical review.

Acral Nevus vs Melanoma: How to Tell the Difference?

An acral nevus is a benign (harmless) mole that appears on the palms or soles. Because these locations are unusual for moles, people often worry unnecessarily, but they can also miss genuine warning signs.

Key Differences Between an Acral Nevus and Melanoma

If you are unsure whether a mark on your foot or hand is an acral nevus or something more serious, always seek professional evaluation. The table above is a guide, not a diagnosis.

How Fast Does Acral Lentiginous Melanoma Grow?

The answer depends on what stage the melanoma is at when first noticed.

Acral lentiginous melanoma typically grows in two phases:

1. Radial (Horizontal) Growth Phase

In its early stages, acral lentiginous melanoma grows outward across the surface of the skin rather than downward into deeper layers. This phase can last months to years. During this time, the lesion may look like an ordinary brown patch or stain, and this is the phase where treatment is most effective.

2. Vertical Growth Phase

If left untreated, the cancer begins to grow downward into the deeper layers of skin and tissue. Once this happens, it becomes harder to treat and more likely to spread to lymph nodes and other organs.

How fast does acral lentiginous melanoma grow? 

There is no single answer. Some lesions remain in the radial phase for years, while others progress more quickly. This unpredictability is exactly why early detection matters so much.

Stages of Acral Lentiginous Melanoma

• Stage 1 acral lentiginous melanoma: The cancer is confined to the outer layers of skin (epidermis). At this stage, it has not spread and is highly treatable.
• Stage 2: The melanoma has grown deeper into the skin but has not yet reached the lymph nodes.
• Stage 3: Cancer has spread to nearby lymph nodes.
• Stage 4: Cancer has spread to distant organs such as the lungs, liver, or brain.

Stage 1 acral lentiginous melanoma has an excellent outlook when treated promptly. The goal of awareness is to catch it at this stage before it progresses.

How Is Acral Lentiginous Diagnosed?

A doctor will follow a structured process if he suspects acral melanoma.

Step 1: Clinical Examination

Your doctor will examine the lesion closely, looking at its size, colour, shape, and borders. They may ask how long you have had it and whether it has changed.

Step 2: Dermoscopy

A dermatoscope is used to look at the lesion under magnification. As described above, dermoscopy for acral melanoma specifically looks for the parallel ridge pattern and other warning signs.

Step 3: Skin Biopsy

Biopsy is the only way to confirm melanoma. This process includes removing a small sample of tissue and examining it under a microscope. This is a straightforward procedure to be performed under local anaesthetic.

Step 4: Staging Tests

Further tests such as an ultrasound, CT scan, or PET scan may be used to determine if melanoma is confirmed to see whether the cancer has spread.

What are the Lentiginous Melanoma Treatment Options?

The treatment for acral lentiginous melanoma depends on the stage at diagnosis and how far the melanoma cancer has spread.

Surgery (Primary Treatment)

For most cases, surgery is the first and most effective treatment. The surgeon removes the melanoma along with a margin of healthy tissue around it (called a wide local excision). For nail melanoma, this may involve removing part or all of the nail and surrounding tissue.

Sentinel Lymph Node Biopsy

If the melanoma is at an intermediate stage, the surgeon may also check the nearest lymph nodes to see if cancer has spread. This procedure helps stage the disease accurately.

Immunotherapy

For advanced acral melanoma, immunotherapy drugs, which help your immune system recognise and attack cancer cells, have transformed outcomes. Drugs such as pembrolizumab and nivolumab are commonly used.

Targeted Therapy

If the melanoma has specific genetic mutations (such as a BRAF mutation), targeted therapy drugs can be used to block the growth of cancer cells.

Radiation Therapy

Radiation is not the first choice for acral melanoma. But it may be used after surgery in some cases or to treat areas where cancer has spread.

Clinical Trials

Given that acral lentiginous melanoma behaves differently from UV-related melanoma. There is ongoing research into new treatment approaches. Your specialist can advise you on whether a clinical trial might be appropriate.

Acral Lentiginous Melanoma Survival Rate and Prognosis

One of the most important factors affecting survival is the stage at which the cancer is diagnosed. Here is a general overview:

• Stage 1 and early Stage 2: When caught early, the acral lentiginous melanoma survival rate is generally high, with five-year survival rates often above 80–90% for localised disease.
• Stage 3: Once cancer has spread to lymph nodes, survival rates decrease but remain meaningful, especially with modern immunotherapy options.
• Stage 4: Advanced disease carries a more serious prognosis, though new treatments have significantly improved outcomes compared to a decade ago.

It is worth noting that acral lentiginous melanoma has historically had a lower survival rate than other melanoma types. This is largely because it tends to be diagnosed later, not because it is inherently more aggressive. That’s why early awareness and action are important.

Survival rates are population-level statistics and do not predict individual outcomes. Speak to your specialist for a personalised prognosis based on your specific situation.

When to Seek Medical Attention?

You should seek medical advice immediately whenever you notice any of the following:

• A new dark stripe or band under a fingernail or toenail that you cannot explain
• A dark stripe that is getting wider
• Skin darkening around the base of a nail (Hutchinson's sign)
• A new brown or black patch on the palm of your hand or the sole of your foot
• Brown patches on the bottom of your feet that are growing or changing
• A freckle on the palm of your hand that has changed shape, colour, or size
• Any lesion on the hands, feet, or nails that bleeds, itches persistently, or fails to heal
• An Abnormal mole in the palm that looks different from your other moles

Remember: If you have any doubt, get it checked. A harmless mole review is far better than a delayed cancer diagnosis. You know your body best; trust your instincts.

Prevention and Self-Check Tips

While acral melanoma cannot always be prevented, regular self-examination dramatically increases the chance of catching it early.

How to Examine Your Hands and Feet?

• Once a month, thoroughly inspect both palms and the backs of your hands in good lighting
• Use a mirror to check between your toes and soles of your feet
• Look at each nail carefully; check for dark stripes or changes around the nail fold
• Ask a partner or family member to check areas that are hard to see
• Take photographs of any marks you are monitoring so you can compare changes over time

General Skin Cancer Prevention

• Use sunscreen regularly, even on cloudy days, on all exposed skin
• Attend annual skin checks with a dermatologist if you have a personal or family history of skin cancer
• Report changing skin lesions to your General Practitioner immediately
• Do not ignore what seems like a simple bruise under a nail that does not grow out; it may not be a bruise at all

Conclusion

Acral melanoma and acral lentiginous melanoma are rare but serious cancers that are far too often caught late. However, finding it at stage 1 or early stage 2 usually allows successful treatment.

Whether you have noticed a suspicious patch on the bottom of your foot, a dark stripe under a toenail, or an unusual freckle on the palm of your hand, the most important step is not to wait. A consultation with a specialist can put your mind at rest or, if there is a problem, start you on the path to treatment before the cancer has a chance to progress.

Book Your Skin Check at Sayyal Health

Sayyal Health has extensive experience in identifying and managing acral melanoma. If you have a mark that concerns you, however small, we are here to help. Early consultation is always the right decision.

Frequently Asked Questions 

what are Melanocytes?

Melanocytes are specialized melanin-producing cells located in the bottom layer of the epidermis (stratum basale), as well as in the eyes, inner ear, and other tissues 

How fast does Acral Melanoma grow?

Acral melanoma usually grows slowly in the early stages but can become more aggressive if not detected early. Growth rate varies by individual and stage.

What is the first stage of Acral lentiginous melanoma?

The first stage (Stage 0 or in situ) is when cancer cells are confined to the outer layer of the skin and have not spread deeper.

How quickly does Acral melanoma spread?

It can spread gradually at first, but once it reaches deeper skin layers, it may spread more quickly to lymph nodes and other parts of the body.

What is the survival rate of Acral melanoma?

Survival rates depend on early detection. When diagnosed early, the 5-year survival rate is high (around 80–90%), but it drops significantly in advanced stages.

 

Medical Disclaimer: This blog has been written for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you may have regarding a medical condition.