Abnormalities in pigmentation are common and frequently produce considerable stress in the patient since they affect appearance. Some of these concerns are purely cosmetic and other pigmentary changes, as with lupus, can signal serious underlying disease. Pigmentary disorders all relate to the amount of the skin pigment melanin. Disorders having excess melanin are known as hyperpigmentary or hypermelanotic diseases. Those with too little melanin or loss of melanin are termed hypopigmentary or hypomelanotic. Hair contains melanocytes and pigment loss here can cause loss of hair pigment with white hair. Melanin is contained within cellular organelles called melanocytes. These are pigment-producing cells found in the basal layer of epidermis. The melanin is then transferred out of the melanocyte packaged in melanosomes to the keratinocyte in the outer layer of epidermis. In caucasians, melanocytes are bound to the cell membrane of the keratinocyte and are of smaller size. In people of color, the melanosomes are dispersed throughout the cell body (cytoplasm) of the keratinocyte and are larger than in whites. Asians and red-haired persons have a slightly different chemical type of melanin.

The many types of pigmentation disorders may present in diverse forms and distributions and have various causes. They can be inherited (eg, vitiligo, familial periorbital hyperpigmentation), acquired (eg, postinflammatory pityriasis alba, idiopathic guttate hypomelanosis, Becker's nevus, melasma), infectious (eg, tinea versicolor), benign and self-limiting (eg, isolated café au lait spots, photocontact dermatitis), or a sign of more serious underlying disease (eg, multiple café au lait spots, malignant acanthosis nigricans).

People of all races have skin pigmentation disorders. Some disorders, like albinism (which affects one out of every 17,000 people) are rare. Others, such as age spots, are very common.