Acral lentiginous melanoma (ALM) is a form of lentiginous melanoma that typically originates on the feet, hands, toenails, fingernails, and inside mucous membranes. ALM accounts for only 5% of melanoma cases in the United States, but is the leading cause of skin cancer deaths.
The disease initially appears as a bruise or nail streak on the skin. Most patients do not notice ALM until it has already begun to spread aggressively throughout the body. Bob Marley was killed from this form of malignant tumor under his toenail.
Malignant ALM (also called subungual melanoma) affects people of Asian or African descent more than any other race or ethnicity. The average patient is between sixty and seventy years of age, but ALM can affect people of any age. This classification of the disease is generally found on the hands, feet and other areas of the body where very little hair grows. Presently, sunlight is not a proven cause of this condition.
Lentigo maligna is a slow growing form that stays dormant for several years. When lentigo maligna becomes malignant, it is classified as ALM.
Melanoma Signs & Symptoms
ALM often affects the skin below the surface, making it very difficult to detect until the onset of aggressive growth and/or drastic changes in shape or color. Common indicators are brown streaks under the toenails or fingernails. ALM can become painful and sometimes mistaken for warts when on the foot.
Nail streaks on fingernails and toenails and bruise-like marks on the skin are common early indicators of ALM. A dermatologist should also be consulted if a patient discovers any moles that increase in size and/or appear irregular in shape or unusual in color. To diagnose ALM, tissue samples are biopsied from areas of the skin that appear abnormal.
These samples are evaluated under a microscope to detect the presence of anomalous and/or cancerous cell populations. Imaging techniques such as x-ray, computed tomography (CT scan), magnetic resonance imaging (MRI), and positron emission tomography (PET scan) are also used to gather information about the tumors size, location, growth rate, and other features. On occasion, samples of the lymph nodes are taken for examination if the tumor appears to have spread aggressively throughout the body.
Melanoma’s that are detected early and are located less then 1.0 mm beneath the skin are usually extracted without the need for additional treatments. If the tumor has invaded more than 1.0 mm into the skin, extraction is still possible, but may additional treatment may be necessary.
Amputation of a toe or finger is often performed to prevent the tumor from spreading throughout the body. Chemotherapy is conducted if traces of the cancer cells are location in other areas of the body. Radiation therapy is frequently used to treat cancers that reemerge after the initial treatment.
If detected early, treatments are often curative and may prevent the spreading of cancerous cells permanently. If the tumor is less then 1.0 mm deep and detected early in its development, the reported five-year survival rate is approximately 90%. When the tumor is deeper then 1.0 mm or has spread to other parts of the body through the lymph nodes, the cancer frequently results in death.