Generally, lentigo maligna melanoma is only somewhat serious, but if left untreated, it may become more serious. When detected early, lentigo maligna melanoma only affects the topmost layer of skin and may be completely removed through surgery and other treatment. However, if the disease is left untreated, it may spread deeper into the skin and may even spread to other parts of the body. At that point, it may not be possible to completely get rid of it and it may become fatal. Because of this, it's important to see a doctor if you notice any symptoms, since the chance for a full recovery is better if you catch lentigo maligna melanoma early.