Acral Lentiginous Melanoma

Introduction: In this article you will find symptoms, pictures , causes, treatment, and pathologic outline for Acral Lentiginous Melanoma.

Also a definition and explanation of metastatic melanoma, genetics and mutation of Acral Lentiginous melanoma will be discussed. Please be sure to seek medical attention if you note any of the signs or symptoms noted below.

The information noted bellow is written based on various studies and medical articles. Please refer to the references below for more detailed information regarding each fact stated.

Well known Facts about Acral Lentigninous Melanoma ALM:

  • Many times Acral Lengigninous Melanoma can look like other skin conditions. The conditions it may adopt to look like are less dangerous. Sometimes medical workers could even misjudge it as a simple bruise.  (1,3,6)
  • ALM is often found in hairless areas such as palms, soles or nail plates. (2,5)
  • The above stated fact is why it was so named Acral, and lentiginous has to do with its growth phases. (1,2,4,6)
  • ALM is a rare subtype of cutaneous melanoma but is the most common diagnosed in the foot. (1,2,3,6)

Please note : The main subtypes of Melanoma are considered to be:

Acral lentiginous Melanoma Symptoms

  • This occurs on volar surfaces of hands and feet, subungual sites, and fingers and toes. (1,3,6)
  • It often shows slow lentiginous radial growth, at times with plaque- like thickening. (6)
  • The tumor cells are heavily pigmented and markedly tick papillary dermis tissue. (6)
  • Most lesions are unusually large and, in many cases, thick and ulcerated.(6)
  • ALM is noted to have dendritic or finger like processes. (1)
  • The tumor will most likely be a brown to black patch at times showing color variation and irregular borders (5)

Acral lentiginous Melanoma Causes

  • Some studies have suggested that trauma to the foot can be a cause. This is because the most common place for the tumor is on the heal or ball of the feet. These areas receive the most impact during walking or running. (6)
  • Prolonged sun exposure (2,6)

Prolonged sun exposure

Picture 1 : Prolonged sun exposure

Image source :


Growth phases are known as:

  • Preliminary radial growth of atypical lentiginous cells at dermal-epidermal interface.
  • Expansible growth into the papillary dermis or infiltrative vertical growth in the reticula dermis.
  • Cytology of themalignant cell
  • Response of the epidermis to the melanocytes
  • Immune response. (1,6)

Diagnosis and Pictures

  • Should be reviewed as a option in the cases of venous ulcers, decubitus ulcers and diabetic foot.
  • ALM only occurs in 2-10% of all melanoma types. (8)
  • Parallel line patterns  (not to be mistaken as a bruise) (6)

Parallel line patterns Acral Lentigninous Melanoma

Picture 2: Parallel line patterns Acral Lentigninous Melanoma

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  • Flat brownblack margins which enlarge slowly and cause no pain. (6)
  • Positive BRAAFF checklist.
  • Dermoscopy may show positive even before evident melanoma characteristics.
  • Punch biopsy or small incision. (6)

Acral lentiginous Metastatic Melanoma

  • Evident with regional lymph node involvement.
  • Adds a poor prognosis.
  • Changes the stage to II or III
  • All involved lymph nodes should be removed with nodal dissection. (6)

Acral lentiginous Melanoma Genetics

  • Lentigines are observed worldwide.
  • The incidence in each person depends on the type and location of the lesion.
  • Solar lentigines are more common in light-skinned whites than in dark-skinned individuals.
  • In dark skinned people the disease is distinctly uncommon due to the natural pigment.
  • They appear to develop earlier in Japanese than in German women.
  • Acral lentigines are more common in dark-skinned individuals, but they may also be present in light-skinned individuals.(2,6)

Acral lentiginous Melanoma Nail

  • The frequently used ABCDE rule is not always helpful in nail acral lentiginous melanoma. This is because of the anatomy and continuous outgrowth in of the nail plate. (5)

nail acral lentiginous melanoma

Picture 3 : Nail acral lentiginous melanoma

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This nail lesion can be seen from the distal third of the nail bed noting that it caused nail detachment.

Please see : ABCDE rule of malignant melanoma

ABCDE rule of malignant Melanoma

Acral lentiginous Melanoma Treatment

  • For subungual lesions minor amputation such as distal phalayngeal amputation, or ray amputation including the distal metatarsal or metacarpal head. (6)
  • It is best if the ball of the foot is saved.
  • Different types of surgery include cryo and laser. (2)
  • Topical creams at times may be successful. (2)
  • The removal of underlying tissue within 2 cm is necessary as seen in the foto. Extending more than 2cm has not shown a significant decrease in re-occurrence.  (4,6)


Picture 4 : Melanoma surgical  wound

Reference :

  • Split-thickness skin graph is necessary for proper healing, the skin graft can come from the thigh.(4,5)

Photo 5 : Split-thickness skin graph melanoma

Image source –

  • If the diagnosis is melanoma then any biopsy scars as well as any lesion or dendrites should be removed. (5,6)
  • When diagnosed melanoma in the fingers or toes digital amputation is needed. (5,6)
  • According to the BRRAAFF checklist the following is a common guide to follow:
  1. Exhibiting a PRP should be excised
  2. Symmetric PFP or symmetric fibrillar pattern should be benign and not be excised
  3. Exhibiting PFP or fibrillary pattern and displaying marked asymmetry should be excised.
  4. Lacking a PRP, PFP or fibrillary pattern should be excised if asymmetry in color or structure is noted. As noted in the following photos.


PRP, PFP or fibrillary pattern Acral lentiginous melanoma

Photo 6 : PRP, PFP or fibrillary pattern Acral lentiginous melanoma

Image Source :

Prognosis and Survival Rate

  • ALM can look a lot like lentigo maligna melanoma but has been noted to be more aggressive and have a worse prognosis. (5)
  • Prognosis is much better the sooner it is diagnosed. (1,2,3,4,5,6,7,8,9)
  • Prognosis is directly related to the size and depth of the tumor or lesion. (1,2,3,4,5,6,7,8,9)
  • Often times the delay in diagnosis is because clinically it can appear to be benign. (1,5)

Please note : Famous musician Bob Marley died of this cancer


 References :

  1. Hyperkeratotic Acral Melanoma Mimicking a Common Wart
  3. The BRAAFF Checklist: A New Dermoscopic Algorithm for Diagnosing Acral Melanoma
  4. Acral Lentiginous MelanomaA Clinicopathologic Entity
  5. Acral Lentiginous Melanoma in Situ: A Diagnostic and Management Challenge
  9. Metástasis laríngea de melanoma lentiginoso acral: imágenes de banda estrecha
    Acta Otorrinolaringol Esp 2016;67:120-1

Published by Dr. Raj MD under Cancer.
Article was last reviewed on March 8th, 2020.

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