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WHO Classification of Tumours
Acral lentiginous melanoma, malignant


Acral lentiginous melanoma (ALM) is a form of malöignant melanoma occurring on the plantar, palmar, subungual, and periungual skin. It presents as a pigmented macular lesion with highly irregular borders; subungual lesions are often associated with thickening, splitting or destruction of the nail plate. The vertical growth phase becomes manifest in form of an elevated papule or nodule, sometimes with a verrucous surface. Ulceration is more frequent in ALM than in other types of melanoma. Histopathologically, ALM consists of atypical spindled and dendritic melanocytes. The epidermis is often hyperplastic, with pagetoid infiltration by anaplastic cells.
Acral lentiginous melanoma is the most common type of melanoma in dark-skinned people and Asians. It typically arises in elderly patients and shows a predilection for males. The prognosis of invasive ALM is generally poor

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LeBoit PE, Burg G, Weedon D, Sarasin A (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Skin Tumours
3rd Edition
IARC Press: Lyon 2005