10 Things You Probably Don't Know about Skin Cancer of the Foot

Health Writer

Acral Lentiginous Melanoma (ALM), skin cancer of the foot, is one of the few skincancers that is not attributed to sun exposure. It most often appears on the soles of the feet, the palms of the hand or under fingernails. While it is one of the least common of the major skin cancers, the survival rate is lower. The following are ten things about ALM that you probably don't know about this potentially deadly skin cancer:

ALM often first appears as a black or brown spot. Many people do not seek treatment immediately because they think it is the result of an injury. The surface may remain flat while the tumor goes deep in the skin.

The first sign of ALM is sometimes a dark streak or stripe under the nail, often on the big toe or thumb. People of color sometimes have streaks under the nail that are benign. You should look for streaks that appear but are not caused by an injury or trauma, wide streaks or nails that seem to be lifting off the nail bed.

ALM occurs much more often on the foot than on the hand. According to one study, 78 percent of ALMs were found on the lower limb with only 22 percent on the upper limb.

Lesions from ALM usually follow the ABCDE rule of skin cancer. They are not symmetrical, have an irregular border, vary in color and evolve with time.

ALM lesions can remain in situ, or remaining in the epidermis, for years before crossing into the dermis and spreading to other parts of the body. However, survival rates are closely related to the thickness of the tumor when diagnosed. Any new lesions or those that change in size or shape should be seen by a dermatologist.

According to a study published in 2009, Asian/Pacific Islanders had the lowest rates of ALM, however, the survival rate for this group was lowest. It is thought that this is due to not seeking treatment until the cancer was further developed.

Two to three percent of all melanomas are acral lentiginous melanoma. Because of the low rate of ALM, there is not as much research on this type of cancer, however, a little more than one-third of all skin cancers diagnosed in people of color are ALM.

Men and women are diagnosed with ALM similarly; however, men have a lower survival rate. This can probably be attributed to women seeking medical treatment during the earlier stages of cancer and therefore receiving earlier treatment.

The age of diagnosis with ALM is higher than that of other types of skin cancer. The mean age for diagnosis for all skin cancer is 58.5 years, compared to 62.8 for ALM.

Acral lentiginous melanoma was not documented as a distinct melanoma until 1986, five years afterBob Marley died from ALM.

For More Information:

Acral Melanoma Not Caused by Sun Exposure

Bob Marley's Skin Cancer

Why Some People Are More at Risk of Melanoma: A HealthCentral Explainer

5 Signs Your Melanoma Has Spread

References:

"Acral Lentiginous Melanoma: Incidence and Survival Patterns in the United States, 1986-2005," 2009, April, JAMA Dermatology

"Progression from Acral Lentiginous Melanoma in situ to Invasive Acral Lentiginous Melanoma," 2009, Jun Min Bae, M.D, Hyung Ok Kim, M.D., Young Min Park, M.D., Annals of Dermatology, doi:10.5021/ad.2009.21.2.185