The diagnosis of vitiligo can usually be made on clinical examination of a patient with progressive, acquired, chalk-white macules in typical sites. Few conditions are as patterned and symmetrical as vitiligo. Sometimes the spots match on both extremities in a mirror-image.

Woods light examination is required to detect all the spots, especially in fair skinned persons, include:

• Lupus erythematosus (atypical distribution, positive immunofluorescence, serologic studies)
• Pityriasis alba (slight scaling, fuzzy margins, off-white color)
• Piebaldism (congenital, white forelock, stable, hyperpigmented macules in the center of white spots, different distribution than vitiligo)
• Tinea versicolor (fine scales with greenish yellow fluorescence under Wood’s light, positive KOH)
• Chemical leukoderma (history of exposure to certain phenolic germicides, confetti macules)
• Post-inflammatory hypomelanosis (off-white macules, history of psoriasis or eczema in the same area)

Diagnosis can usually be established on clinical grounds alone. In certain difficult cases, a skin biopsy may be required to exclude some of the above. A defining feature is that pigment cells in the skin are absent in vitiligo. Vitiligo is sometimes associated with general diseases.

Vitiligo may be associated with thyroid disease (up to 30%, especially women), diabetes mellitus (probably less than 5%), pernicious anemia (increased risk), Addison’s Disease (increased risk), and multiple endocrinopathy syndrome. Associated cutaneous conditions include white hair and prematurely grey hair, alopecia areata, and halo nevi. There is no increased risk for malignancy. Skin cancers (all types) appear to be unusual.

Ophthalmologic (eye) examination may reveal evidence of healed chorioretinitis or iritis (probably less than 10%). Vision is unaffected. There are no important hearing changes. Laboratory studies for detection of general diseases associated with vitiligo include:

Thyroid profile: especially TSH (radioimmunoassay)
Fasting blood sugar (to rule out diabetes)
Complete blood count with indices (to rule out pernicious anemia)