Acral Lentiginous Melanoma

The name acral lentiginous melanoma refers to location and coloring, with “acral” meaning occurrence on the palms or soles, and “lentiginous” meaning that the spot of melanoma is much darker than the surrounding skin.

Tumors develop when melanocyte cells in the skin begin to grow uncontrollably. Because these cells house melanin (or pigment), their overproduction leads to spots that are a different color than normal skin tone.

Where Is It Located?

Acral lentiginous melanoma is most likely to appear:

• On the palms of the hands
• On the soles of the feet
• Under fingernails or toenails

Symptoms of ALM may vary depending on the cancer’s location and stage.

Common signs and symptoms include:

• Unexplained streaks that run vertically across a toenail or fingernail bed
• A new or changing mole on the hands or feet
• Black, gray, tan or brown spot, patch or discoloration with irregular borders on the palms or soles
• Changing or growing lesion on the foot or hand
• Reddish, pinkish or orangish lesion with irregular borders
• Thick patch of skin on the sole or palm
• Itchy, bleeding or inflamed spot or patch on the hands or feet

When it comes to effectively treating acral lentiginous melanoma, early detection matters and typically involves a multidisciplinary approach, including:

• Clinical examination, or thoroughly observing the skin to look for characteristics of ALM with a board-certified dermatologist
• Dermatoscopy, a specialized technique involving a handheld tool that magnifies and brightens the skin
• Histopathology, which examines tissues under a microscope to check for signs of disease
• Molecular testing, which searches for a specific gene, protein or other molecules in the tissue sample
• Radiological imaging, various imaging techniques like CT scans, MRI and ultrasound to describe, diagnose or monitor disease
• Blood tests, which can indicate presence of specific enzymes, especially in late-stage acral melanoma
• Skin biopsy, or surgically removing suspicious skin tissue for lab analysis to definitively diagnosis ALM

Staging — a key step in the diagnostic process — tells doctors how much cancer is in the body and whether it has spread to other areas. For acral melanoma and other subtypes of melanoma, staging is based on the American Joint Committee on Cancer (AJCC) TNM system, which assign stages based on three factors:

• Tumor size and location (T)
• Spread to nearby lymph nodes (N)
• Metastasis to other parts of the body (M)

Below is a staging summary for acral lentiginous melanoma, based on various considerations of the TNM grading system.

Acral lentiginous melanoma is typically treated with surgery. The goal is to remove the tumor as well as a margin of healthy surrounding skin. In some cases, the surgeon may also remove nearby lymph nodes to check whether the cancer has spread.

Other treatments for ALM include:

• Radiation therapy
• Chemotherapy
• Immunotherapy
• Targeted therapy, based on a genomic mutation in the tumor

Treatments may be used alone or with surgery, depending on cancer's stage and extent.

Who Treats Acral Lentiginous Melanoma?

Finding specialized care is critical with cancer as rare as acral lentiginous melanoma. The patient’s team of multidisciplinary experts may include:

• A dermatologist, who diagnoses and treats diseases affecting the skin
• A Mohs surgeon, who is a specially-trained surgeon who act as the pathologist and surgeon and can provide real-time analysis of the margins
• A surgical oncologist, who uses surgical techniques to remove cancer
• A medical oncologist, who treats cancer with drugs such as chemotherapy, immunotherapy or targeted therapy
• A radiation oncologist, who uses high-energy beams of radiation to destroy cancerous tissue
• A pathologist, who examines tissue samples for diagnostic purposes to help determine a treatment plan
• A radiologist, who utilizes imaging tools and interventional techniques to diagnose and treat cancer
• Supportive care providers, who focus on cancer- and treatment-related side effects and symptom management

The prognosis for acral lentiginous melanoma depends on the tumor's size, location, stage at diagnosis and overall health of the patient. Because ALM often goes unnoticed for so long, its mortality rates are higher in comparison to other types of melanoma. Research also shows that less advanced cancers and thinner tumors have better survival rates versus raised tumors.

A study in JAMA Dermatology found that ALM outcomes vary among different populations, possibly due to differences in medical care or the likelihood of noticing and seeking treatment for skin cancer.

Survival rates also vary:

Non-Hispanic white people have an 82.6% chance of surviving at least five years after ALM diagnosis, and 69.4% survive for 10 years or more.

African Americans have a 77.2% five-year survival rate and 71.5% for 10 years or more.

Hispanic people have a 72.8% five-year survival rate and 57.3% for 10 years or more.

Asians and Pacific Islanders have a 70.2% five-year survival rate and 54.1% for 10 years.

Talk to your care team for an individualized prognosis based on the cancer’s stage, your overall health and other factors.