Acral melanoma is a cancer that arises from normal melanocyte cells in "glabrous" (meaning non-hair bearing) skin. One of the most common sites is on the plantar surface of the foot, mostly the heel. They can also develop on the palms of the hands, or on surfaces of the fingers and toes. When these melanomas develop underneath the fingernails or toenails, they are referred to as "subungual" melanomas.