The appearance of skin patches that are darker than the surrounding skin color is usually caused by natural body processes, and sometimes by external causes. The term for this skin darkening is epidermal hyperpigmentation. Epidermis refers to the outer layer of the skin. Hyperpigmentation means excess color. Hyperpigmentation refers to brown skin spots which are caused by an increase in the amount of melanin, a pigment in the skin that also determines eye and hair color.
Epidermal hyperpigmentation occurs when too much melanin is produced and forms deposits in the skin.
Hyperpigmentation usually develops gradually and becomes markedly more apparent after sun exposure and tanning. Hyperpigmentation is not a medical harmful condition. It is advisable, however, to have darkened skin patches checked by a physician to make sure they are not a type of skin cancer. Usually people seek treatment for hyperpigmentation because it is cosmetically displeasing for them. Skin lightening products prescribed by a physician can reduce the unwanted excess color of hyperpigmented skin patches.