Acral Lentiginous Melanoma - Symptoms, Causes & Treatment
By ScanSkinAI Editorial Team✓ Reviewed for medical safetyLast updated June 2026
A type of melanoma that occurs on the palms of hands, soles of feet, or under nails. It's the most common type of melanoma in people with darker skin and is often diagnosed at a more advanced stage.
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Quick Answer
Acral lentiginous melanoma is a serious skin cancer that develops on the palms, soles, or underneath the nails. Unlike other melanomas, it is not caused by sun exposure and affects all skin tones equally, making it the most common melanoma in darker-skinned individuals. It usually appears as an irregular dark patch or a widening dark streak under a nail. Because it is easily mistaken for a bruise or fungal infection, diagnosis is often delayed. Early detection by a doctor is crucial for successful treatment and survival.
Clinical Context
Acral lentiginous melanoma (ALM) accounts for only 2-3% of melanomas in Caucasians but 30-70% in darker-skinned populations. Unlike other melanomas, it's not related to UV exposure, making it the equalizer across skin types. ALM is often diagnosed at a more advanced stage due to delayed recognition, contributing to worse outcomes. The hallmark under nails is Hutchinson's sign - pigment extending onto the nail fold. Bob Marley died from undiagnosed ALM under his toenail. Early detection is critical for survival.
Symptoms
- Dark spot or streak on palm, sole, or under nail
- Irregularly shaped patch with uneven borders
- Brown or black discoloration that changes over time
- Under nail: dark longitudinal band that may widen
- Hutchinson's sign (pigment extending to nail fold)
- May ulcerate or bleed in advanced stages
Severity & Progression
Causes & Risk Factors
- Genetic mutations (KIT mutations common in ALM)
- Unknown environmental factors
- Not associated with sun or UV exposure
- May relate to repeated mechanical trauma
- Genetic predisposition
May Be Confused With
This condition can look similar to other skin conditions. A healthcare professional can help distinguish between them.
Treatment & Management
Surgery is the primary treatment - wide local excision with appropriate margins. Nail melanomas may require amputation of the affected digit. Sentinel lymph node biopsy is performed for invasive tumors to detect spread. Advanced ALM responds to immunotherapy (checkpoint inhibitors like pembrolizumab and nivolumab). KIT-mutated ALM may respond to targeted therapies (imatinib). Regular surveillance is essential due to high recurrence risk.
- Wide surgical excision with margins
- Amputation of digit for advanced nail melanoma
- Sentinel lymph node biopsy for staging
- Immunotherapy (pembrolizumab, nivolumab) for advanced disease
- Targeted therapy for KIT-mutated tumors (imatinib)
- Regular surveillance for recurrence
Red Flags & Complications
Seek medical attention if you experience any of the following:
- Late diagnosis due to hidden location
- Metastasis to lymph nodes and distant organs
- Recurrence after treatment
- Functional impairment from surgery on hands/feet
- Poorer prognosis compared to other melanomas due to late detection
Self-Care Tips
- Examine palms, soles, and nails monthly
- Check between toes and toe webs
- Use a mirror to see sole of foot
- Take photos to track any changes
- Know your baseline nail pigmentation patterns
When to See a Doctor
IMMEDIATELY if you notice any new dark spots on palms or soles, dark streaks under nails (especially if widening), pigment extending to nail fold (Hutchinson's sign), or any changing lesion in these areas
Frequently Asked Questions
What does acral lentiginous melanoma look like?
On the palms or soles, it usually starts as a flat, irregularly shaped brown or black patch that changes over time. Under a nail, it often appears as a dark vertical streak that gradually widens. A key warning sign, known as Hutchinson's sign, occurs when the dark pigment spreads from the nail onto the surrounding skin. Advanced spots might ulcerate or bleed.
Can I get this type of melanoma if I stay out of the sun?
Yes. Keep in mind that acral lentiginous melanoma is entirely unrelated to sun or UV exposure. This means it can develop regardless of your sun protection habits. While the exact cause remains unknown, it is linked to certain genetic mutations and possibly repeated mechanical trauma to the hands or feet. Everyone should regularly check their palms, soles, and nails.
Who is most at risk for developing this cancer?
Acral lentiginous melanoma affects people of all races and genders, usually developing in adults over 60. Because sun-related melanomas are rare in darker skin, this condition accounts for the majority of melanomas seen in people of African, Asian, and Hispanic descent. Delayed evaluation is the biggest risk factor for poor outcomes, as these hidden areas are often overlooked during routine checks.
How can I tell if the line under my nail is cancer or just a bruise?
It can be very difficult to tell the difference at home. A bruise from an injury goes away over time as the nail grows out. A melanoma streak will persist, often gradually widening or becoming darker. If a dark streak appears under your nail without a known injury, spreads to the skin around the nail, or does not grow out over several weeks, you should have it evaluated by a doctor immediately.
How is melanoma on the hands or feet treated?
The primary treatment is complete surgical removal of the tumor along with a margin of healthy tissue. For advanced melanomas under the nail, this occasionally requires amputating part of the affected finger or toe to ensure the cancer is fully removed. If the cancer has spread within the body, doctors may use immunotherapy or targeted medications to help fight the disease.
Is acral lentiginous melanoma curable?
Yes, it is highly curable if caught very early, while the cancer is still confined to the top layer of the skin. However, this specific type of melanoma generally has a lower survival rate than others simply because it is discovered at a more advanced stage. Because spots on the soles or nails are easily ignored, prompt medical evaluation of any changing dark spot is absolutely critical.
How can ScanSkinAI help me check for acral lentiginous melanoma?
ScanSkinAI provides an accessible way to monitor suspicious spots on your palms, soles, or nails over time. By analyzing your photos, our AI acts as an initial screening aid to help you track changes in size, shape, or color. Please remember that ScanSkinAI cannot diagnose cancer. Any new, changing, or unusual dark patch or nail streak must be formally evaluated by a medical professional.
When should I see a doctor about a spot on my foot or hand?
You should consult a doctor as soon as possible if you notice a new dark patch with uneven borders on your palm or sole, or a dark streak under your nail that widens. Prompt attention is also vital if a spot begins to bleed, ulcerate, or if pigment creeps from a nail onto the surrounding skin. Do not wait for it to hurt, as early melanomas are generally painless.
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Medical References
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Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. The content on this page should not be used to diagnose or treat any health problem. Always consult with a qualified healthcare professional for proper medical evaluation, diagnosis, and treatment of your condition.