How Aggressive Is Acral Lentiginous Melanoma?

General signs of skin cancer include changes in skin lesions or moles, or the development of new moles that can be remembered by the ABCDE’s: 

• Asymmetry – Irregularly shaped, each half looks different
• Border – Jagged, uneven, irregular edges
• Color – Mole is several different colors
• Diameter – Size greater than ¼ inch (about the side of an eraser on the end of a pencil)
• Evolution - Changes in size, shape, or color

Signs and symptoms of acral lentiginous melanoma include: 

• A dark spot of skin surrounded by skin that remains normal skin color
• A clear border between the dark skin and the lighter skin around it
• Some spots may be reddish or orange in color 
• A new streak in a nail not caused by an accident or bruise
• A nail streak that damages the fingernail
• A changing spot in or connected to a mole on the foot or hand
• An irregularly-shaped growth on the foot or hand that is changing, growing, or has an unusual color
• An elevated, thickened patch growing on the sole of the foot or palm of the hand

Unlike most types of melanoma, acral lentiginous melanoma does not seem to be related to sun exposure. It is caused by the development of malignant pigment cells (melanocytes) along the basal layer of the epidermis but it is unknown what triggers the melanocytes to become malignant. 

It may be due to genetic risk factors in some cases.

Acral lentiginous melanoma is diagnosed with a physical examination of the affected skin or nails, along with tests such as: 

• Dermoscopy
• Biopsy

The tumor may be measured by Breslow thickness, which is the thickness of an invasive melanoma in millimeters measured from the granular cell layer to the deepest tumor cell. The thicker the melanoma, the more likely it is to spread (metastasize). 

The initial treatment for acral lentiginous melanoma is to surgically remove the tumor along with a margin of healthy tissue that surrounds the tumor. 

Further treatment depends on the thickness of the lesion as determined by the Breslow depth. Other treatment may involve: 

• A skin graft to close the wound
• Partial amputation of a finger or toe
• Radiotherapy 
• Removal of lymph nodes if they are enlarged due to metastatic melanoma
• If the melanoma is widespread, other treatment may include: 
  • Immunotherapy
  • Biologics such as ipilimumab
  • BRAF inhibitors such as vemurafenib and dabrafenib 

Staging for acral lentiginous melanoma is based on the American Joint Committee on Cancer (AJCC) cutaneous melanoma staging guidelines:

• Stage 0: In situ melanoma 
• Stage 1: Thin melanoma less than 2 mm in thickness 
• Stage 2: Thick melanoma greater than 2 mm in thickness 
• Stage 3: Melanoma spread to involve local lymph nodes 
• Stage 4: Distant metastases have been detected

Life expectancy for cancer is often expressed in five- or 10-year survival rates, that is, how many people will be alive five or 10 years after diagnosis. 

The survival rate for acral lentiginous melanoma is: 

• Five-year melanoma-specific survival rate of 80.3% 
• 10-year melanoma-specific survival rate of 67.5%