Lentigo maligna on cheek of an elderly woman. Normal lentigo is common in the elderly and light-skinned people who have been exposed to a lot of sun. Flat and discolored areas are seen similar to freckles. Lentigo maligna, however, is a sign of the pigmentation developing into a malignant melanoma, the most serious type of skin cancer. Malignant melanoma is a tumor of melanocytes, the cells that produce melanin (the pigment that colors the skin, hair and iris). Unless diagnosed and treated early, this tumor is highly malignant and can spread throughout the body.