What are the best sun spot removal & melasma treatments? Overview Hyperpigmentation is the darkening of an area of the skin (or nails) caused by increased melanin. Causes of hyperpigmentation include: Sun damage Melasma Inflammation Skin injuries (including those related to acne) Diseases such as Addison's disease, Cushing's disease, acanthoses nigricans, etc Induced by dermatologic laser procedures Melanin is produced by melanocytes (a type of cell) at the lower layer of th