Vitiligo is characterized by flat macules (patches) of depigmented (colorless) skin, usually completely lacking in functioning melanocytes (cells that produce melanin, the substance responsible for skin color). Macules are usually uniformly milk or chalk-white in color and may not be apparent in very light-skinned people. In dark-skinned people, however, the sharp contrast makes the macules very obvious. Macules tend to have discrete margins and may be round, oval or linear in shape, though they are usually irregular. In some cases, they may be surrounded by margin of darker-than-normal skin.

Macules may vary in size from very tiny to covering large portions of the body and may occur anywhere. The areas most commonly affected include:

• Exposed areas (e.g., face, hands)
  
  
• Areas around body openings (e.g., mouth, nose, eyes, nipples, naval, genitals)
  
  
• Bodily folds (e.g., underarms, groin)
  
  
• Sites of injuries (e.g., scrapes, cuts, burns)
  
  
• Sites subjected to repeated trauma (e.g., bony prominences)
  
  
• Sites of pressure or repeated contact with clothing (e.g., belts, shoulder straps, collars)

Vitiligo macules typically enlarge over time, though the rate of this may be slow or rapid. Loss of color may also occur on mucous membranes (e.g., inside the mouth). When vitiligo affects the scalp, it may cause a localized patch of depigmented hair. This may result in the total depigmentation of all scalp hair or no more than a scattering of white hairs.

Vitiligo patients are usually in good health. This condition typically occurs with no signs or symptoms other than the characteristic macules. In some rare cases, swelling or inflammation may occur immediately prior to the onset of vitiligo. Occasionally, early vitiligo macules may be itchy (pruritus).

Vitiligo may be associated with certain endocrine system disorders, although researchers have not been able to define this connection. The most common of these are hyperthyroidism and hypothyroidism, autoimmune disorders of the thyroid gland.

Other autoimmune conditions that may be associated with vitiligo include:

• Pernicious anemia (low red blood count due to failure to absorb vitamin B₁₂)
  
  
• Addison’s disease (decreased production of certain hormones)
  
  
• Alopecia areata (patches of baldness)
  
  
• Uveitis (inflammation of certain internal eye structures)
  
  
• Diabetes mellitus (a disorder in the body’s ability to break down blood sugar)
  
  
• Lupus (chronic inflammatory disease that affects the skin, joints, blood, and kidneys)

Individuals who notice unusual loss of coloring in their skin, hair or eyes should consult with a physician. The earlier vitiligo is diagnosed, the sooner treatment to prevent or slow further depigmentation can begin.