A
lentigo (plural
lentigines, ) is a small pigmented spot on the skin with a clearly defined edge, surrounded by normal-appearing skin. It is a harmless (benign)
hyperplasia of
melanocytes which is linear in its spread. This means the
hyperplasia of melanocytes is restricted to the cell layer directly above the
basement membrane of the
epidermis where melanocytes normally reside. This is in contrast to the "nests" of multi-layer melanocytes found in
moles (melanocytic
nevi). Because of this characteristic feature, the adjective "lentiginous" is used to describe other skin lesions that similarly proliferate linearly within the basal cell layer.