Skin cancer is the most common form of cancer in the United States, and experts estimate that doctors diagnose skin cancer in around 3.3 million Americans every year. Basal and squamous cell cancers and melanomas are the most common types of skin cancer, but many people know less about some of the rarer forms of the disease. Learn more about acral lentiginous melanoma, and find out if you or your loved ones are at risk from this form of skin cancer.
About the disease
A lentigo is a small pigmented spot on your skin that has a sharp, clearly defined outer edge. Lentigines are rather like freckles, but these spots don't change in the same way you may expect with a freckle. While freckles can increase in number and darkness after sun exposure, a lentigo will normally stay the same.
Acral lentiginous melanoma (ALM) is a form of skin cancer that affects one or more of these lentigines. The cancer starts as a flat patch of discolored skin that slowly grows larger over time. While the malignant cells initially stay within the lentigo, the cancer can become invasive, at which stage the cancer can penetrate the dermis and spread further into the body.
Signs and symptoms
ALM is an unusual form of skin cancer because the symptoms generally appear in unusual parts of the body. People with the disease can experience the symptoms on the following parts of the body:
- The palms of the hand.
- The soles of the feet.
- Beneath a toe or fingernail.
ALM will often initially look like a stain. The melanoma is not always colored, but these cancers can appear in a variety of colors, including brown, blue-gray, black and red. When looking for ALM, a specialist will always look for the regular signs of skin cancer (including asymmetry and border irregularity), but these melanomas are often larger than other skin cancers. You may also see some ulceration and bleeding.
It's easy to mistake the signs of the disease for something else. For example, a melanoma on the bottom of your foot may cause the same painful symptoms you would experience with a plantar wart. It's also often harder to see the symptoms if you have darker skin.
People at risk
This type of skin cancer is rare, and doctors don't understand what causes these melanomas. Crucially, sun exposure does not cause ALM, which is why you can find the cancer in parts of the body that don't generally get any sunlight.
The disease equally affects men and women but normally only appears in people over the age of 40. This type of cancer accounts for less than 1 percent of all melanomas in fair-skinned people, but between 29 and 72 percent of melanomas in dark-skinned people. The famous singer Bob Marley died from this type of cancer, and doctors did not recognize this as a distinct form of the disease until five years after his death.
Diagnosis and treatment
A specialist can often diagnose this type of cancer via a dermoscopy. This painless diagnostic uses a high-powered magnifying lens and lighting system to allow close-up examination of the skin structure. During this procedure, a specialist will look for specific signs that could point to an ALM diagnosis, such as blue-gray structures in the skin. If a specialist sees something suspicious, he or she will normally then ask for a skin biopsy, where he or she will remove a piece of skin from the affected area for laboratory analysis.
Following diagnosis, most people will need skin cancer surgery to remove ALM. These surgical procedures are often more complex than for other skin cancer treatments because of the parts of the body affected. People with the disease may also undergo chemotherapy and radiation therapy to tackle cancer that has spread to other parts of the body.
ALM is a rare form of skin cancer, but dark-skinned people are at higher risk. Talk to a doctor, such as those at Countryside Dermatology & Laser Center, for more information and advice about this condition.