Acral Lentiginous Melanoma
Acral lentiginous melanoma (ALM) makes up majority of melanomas arising in dark-skinned races and accounts for 8-10% of all melanomas in Caucasians. The most commonly involved sites are palms, soles, subungual region (of great toe and thumb), mucocutaneous junction of oral and nasal cavities, and anus. Most patients are elderly with a female predominance.
The in-situ lesions present as slowly enlarging, variably-pigmented macules with irregular borders. The development of deeply pigmented blue-black nodules with/without ulceration (this case showed ulceration) indicates progression to vertical (invasive) growth phase.