Paleness of the skin refers to an abnormal lightening of the skin or mucous membranes. Pale skin may be generalized (occurring all over the body) or localized to one area. It is often accompanied by paleness or pallor in the linings of the eyes, inside of the mouth, and on the surface of the tongue. True paleness of the skin is related to the thickness and density of blood vessels beneath the skin and not to the amount of melanin (skin pigment) that is present. However, some people may confuse loss of skin pigmentation (as with albinism) with paleness. In dark-skinned people, paleness may only be apparent when examining the mucous membranes. Pale skin generally results from a decrease in blood flow, as with fainting or shock. It may also result from a reduction in the number of red blood cells (anemia).