The diagnosis of vitiligo is usually based on clinical examination of a patient with acquired, milk-white spots on typical sites. Vitiligo is usually patterned and symmetrical. In some patients the spots match on both extemities in a mirror-image. Particularly in fair skinned persons Woods light examination is required to detect all the depigmented areas.
Conditions that may look similar to Vitiligo include:
Lupus erythematosus (depigmentation areas present an atypical distribution, and tests like immunofluorescence, and other serologic studies are positive)
Pityriasis alba (slight scaling, fuzzy margins)
Tinea versicolor (fine scales, spots show different colors)
Chemical Vitiligo (history of exposure to certain phenolic compounds)
Post-inflammatory hypomelanosis (history of psoriasis or eczema in the same area)
Idiopathic guttate hypomelanosis is an acquired, benign depigmentation. The cause is not known. It is most commonly a complaint of middle-aged, light-skinned women, but is increasingly seen in both sexes and older dark-skinned people. It is a benign condition. The cause is not known but appears to be related to the effect of long term, excessive, sunlight exposure.
A
Wood's lamp test is helpful to differentiate different types of depigmentation. Only in a small number of particularly difficult cases, a skin biopsy may be required to differentiate Vitiligo from some of the above conditions. There is NO increased risk for malignancy (skin cancers) in people with Vitiligo.
Vitiligo may be associated with thyroid disease (especially women over the age of 40), diabetes mellitus, pernicious anemia, Addison's Disease, and multiple endocrinopathy syndrome. Associated cutaneous conditions include white hair, prematurely grey hair, and alopecia areata. Because of this kind of association your doctor may prescribe any of the following tests:
Thyroid profile: especially TSH
Blood sugar (to rule out diabetes)
Complete blood count, Vit B12 levels, etc (to rule out pernicious anemia).
Occasionally
specific tests for other autoimmune diseases.