Every case of melasma starts off in the epidermis, where melanocytes are actively producing pigment. A normal case of melasma can turn into dermal melasma if skin becomes over-irritated and inflamed. When this happens, it causes a temporary split between the dermis and epidermis. During this time, hyperpigmented cells can drop from the epidermis into the dermis. Once in the dermis, these cells become very resistant to topical treatment. This is one reason why it is so important to avoid aggressiveness in the treatment of melasma.