Acral Lentiginous Melanoma: Signs, Symptoms, and Complications - Verywell Health

Acral lentiginous melanoma (ALM) is a rare type of skin cancer that appears on the palms of the hands, the soles of the feet, or under the nails. ALM is unique because it is an aggressive form of melanoma that is not caused by sunlight and ultraviolet (UV) rays that damage the skin.

ALM commonly appears as a rapidly spreading, darkly pigmented patch, with varying degrees of colors and irregular borders. This article will explain the common symptoms and complications, and you'll learn when you should see your healthcare provider for evaluation.

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Frequent Symptoms

The earliest sign of acral lentiginous melanoma is an oddly shaped and discolored patch of skin surrounded by normal skin. The skin may be raised; black, gray, tan, red, or brown in color; and have irregular borders. Sometimes a brown or tan streak may appear under the nail of your hands or feet, especially the big toe or thumb.

As with other flat forms of melanoma, the "ABCDE" rule is used to help describe these ominous-looking moles, with:

• "A" for asymmetry
• "B" for border irregularity
• "C" for color variation
• "D" for diameter, which is large
• "E" for its ever evolving, or growing, nature

ALM is incredibly rare. However, if you see one or more of the following skin changes, check in with a healthcare professional or dermatologist:

• Ulceration or bleeding at the sight of a new oddly shaped or discolored patch of skin
• A discolored skin patch that has grown in size 
• An irregular area of skin greater than 6 millimeters
• A skin patch that has changed in shape
• A raised surface of the skin 
• A skin patch that has changed in color
• A skin patch that has developed Irregular borders
• Inflammation
  

Other warning signs include:

• A new streak in a nail that is a birthmark or due to an accident or bruise
• A nail streak that has damaged the fingernail
• A mole that has changed in color or shape on your hand or foot 
• A raised, thickened patch on your sole or palm

Prevalence of ALM

ALM is the least common subtype of all melonomas. However, ALM accounts for 70% of melanomas in Black people, 46% in Asian people, and less than 10% in White people.

Rare Symptoms

In rare cases, ALM may appear red or orange—a condition known as amelanotic (nonpigmented) melanoma.

Initially, the cancer cells in ALM remain at the skin's surface (a layer called the epidermis) but can become invasive and spread as the condition advances. Dimpling of the skin and a growing wart that resembles a plantar wart (small growths often appearing on the bottom of feet) or fungal infection may indicate that the tumor is spreading aggressively.

ALM commonly occurs under the nail bed, a condition known as subungual melanoma. It may present with varied discoloration or irregular pigmented longitudinal bands or lines (running lengthwise, not across) on the nail plate (the hard part of the nail). Advanced melanoma destroys the nail plate altogether.

Complications

ALM is a subtype of cutaneous melanoma and an aggressive form of cancer that can spread quickly throughout the body. If left untreated, it can be life-threatening.

Getting an accurate diagnosis as early as possible is imperative to starting proper treatment. It can also give your healthcare team—which likely will consist of an oncologist (cancer specialist), dermatologist (specialist of the skin, hair, and nails), nurses, and support staff—a better idea of your outlook.

When to See a Healthcare Professional

ALM is incredibly aggressive, so prompt diagnosis and treatment are key to limiting its spread and the development of medical complications.

If you notice that a preexisting mole is growing bigger, skin changes such as raised patches are appearing, darkening skin is surrounded by normal skin, or bleeding or ulcerated skin that hasn't been caused by an injury, seek immediate medical attention.

Using the ABDCE technique can also help you spot ominous skin changes. Sudden and unexplained weight loss and more frequent infections may also be signs of a serious illness, like cancer. If you have a history of cancer or do not feel like your normal self, see your primary care physician or another trusted healthcare professional for a checkup.  

Summary

Acral lentiginous melanoma is a rare and aggressive type of melanoma that occurs on the palms of the hands or the soles of the feet without damage from overexposure to sunlight. Common signs of ALM are an unusually shaped, raised and discolored patch of skin, dark patches surrounded by  normal-appearing skin, and bleeding within an existing mole that may enlarge slowly over time.

A Word From Verywell

If you have a mole that is growing in size or changing in color, you may want to get it checked by a dermatologist. While ALM is a serious type of melanoma, it's important to note that it is incredibly rare. Even in the presence of symptoms, it is likely that your changes can be explained by some cause other than ALM. 

That said, it's still important to seek a consultation from a healthcare professional if you notice any skin changes on your body.