Acral lentiginous melanoma is an aggressive type of skin cancer that is not caused by sunlight. Melanoma is a group of serious skin cancers that arise from pigment cells (melanocytes); acral lentiginous melanoma is a kind of lentiginous skin melanoma. Acral lentiginous melanoma is the most common subtype in people with darker skins and is rare in people with lighter skin types. It is not caused by exposure to sunlight or UV radiation, and wearing sunscreen does not protect against it. Acral lentiginous melanoma is commonly found on the palms, soles, under the nails, and in the

oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed '' lamina propria''. The oral cavity has sometimes been des ...

. It occurs on non-hair-bearing surfaces of the body, which have not necessarily been exposed to sunlight. It is also found on mucous membranes. The absolute incidence of ALM is the same for people of all skin colors, and has not changed significantly for decades. However, because rates of other melanomas are low in non-white populations, ALM is the most common form of melanoma diagnosed amongst

Asian Asian may refer to: * Items from or related to the continent of Asia: ** Asian people, people in or descending from Asia ** Asian culture, the culture of the people from Asia ** Asian cuisine, food based on the style of food of the people from Asi ...

and sub-Saharan African ethnic groups. The average age at diagnosis is between sixty and seventy years.

Signs and symptoms

Typical signs of acral lentiginous melanoma include the following * Longitudinal tan, black, or brown streak on a nail * Pigmentation of proximal nail fold * Areas of dark

pigmentation A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compoun ...

(palms of hands) Warning signs are new areas of pigmentation, or existing pigmentation that shows change. If caught early, acral lentiginous melanoma has a similar cure rate as the other types of superficial spreading melanoma.

Causes

Acral lentiginous melanoma is a result of malignant melanocytes at the membrane of the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

(outer layers). The pathogenesis of acral lentiginous melanoma remains unknown at this time. It is not caused by sunlight or UV radiation.

Diagnosis

Although the ideal method of diagnosis of melanoma is complete excisional biopsy, alternatives may be required according to the location of the melanoma.

Dermatoscopy Dermatoscopy also known as dermoscopy or epiluminescence microscopy, is the examination of skin lesions with a dermatoscope. It is a tool similar to a camera to allow for inspection of skin lesions unobstructed by skin surface reflections. The d ...

of acral pigmented lesions is very difficult but can be accomplished with diligent focus. Initial confirmation of the suspicion can be done with a small wedge biopsy or small punch biopsy. Thin deep wedge biopsies can heal very well on acral skin, and small punch biopsies can give enough clue to the malignant nature of the lesion. Once this confirmatory biopsy is done, a second complete excisional

skin biopsy Skin biopsy is a biopsy technique in which a skin lesion is removed to be sent to a pathologist to render a microscopic diagnosis. It is usually done under local anesthetic in a physician's office, and results are often available in 4 to 10 days. ...

can be performed with a narrow surgical margin (1 mm). This second biopsy will determine the depth and invasiveness of the melanoma, and will help to define what the final treatment will be. If the melanoma involves the nail fold and the nail bed, complete excision of the nail unit might be required. Final treatment might require wider excision (margins of 0.5 cm or more), digital amputation, lymphangiogram with lymph node dissection, or chemotherapy.

Histology

The main characteristic of acral lentiginous melanoma is continuous proliferation of atypical melanocytes at the dermoepidermal junction. Other histological signs of acral lentiginous melanoma include

dermal The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided ...

invasion and

desmoplasia In medicine, desmoplasia is the growth of fibrous or connective tissue. It is also called desmoplastic reaction to emphasize that it is secondary to an insult. Desmoplasia may occur around a neoplasm, causing dense fibrosis around the tumor, or ...

. According to Scolyer '' et al.'', ALM "is usually characterized in its earliest recognisable form as single atypical melanocytes scattered along the junctional epidermal layer".

Treatment

Therapies for metastatic melanoma include the biologic immunotherapy agents ipilimumab, pembrolizumab, and nivolumab; BRAF inhibitors, such as vemurafenib and dabrafenib; and a MEK inhibitor trametinib.

Prognosis

It has been demonstrated that acral lentiginous melanoma has a poorer prognosis compared to that of cutaneous malignant melanoma (CMM).

Society and culture

Jamaican musician

Bob Marley Robert Nesta Marley (6 February 1945 – 11 May 1981; baptised in 1980 as Berhane Selassie) was a Jamaican singer, musician, and songwriter. Considered one of the pioneers of reggae, his musical career was marked by fusing elements o ...

died of the condition in 1981, aged 36.

References

External links

{{DEFAULTSORT:Acral Lentiginous Melanoma Melanoma