The diagnosis of vitiligo is made based on a physical examination, medical history, and laboratory tests.
A doctor will likely suspect vitiligo if you report (or the physical examination reveals) white patches of skin on the body, particularly on sun-exposed areas, including the hands, feet, arms, face, and lips. If vitiligo is suspected, the doctor will ask about your medical history. Important factors in the diagnosis include a family history of vitiligo; a rash, sunburn, or other skin trauma that occurred at the site of vitiligo 2 to 3 months before depigmentation started; stress or physical illness; and premature graying of the hair (before age 35). In addition, the doctor will ask whether you or anyone in your family has had any autoimmune diseases and whether you are very sensitive to the sun.
To help confirm the diagnosis, the doctor may take a small sample (biopsy) of the affected skin to examine under a microscope. In vitiligo, the skin sample will usually show a complete absence of pigment-producing melanocytes. On the other hand, the presence of inflamed cells in the sample may suggest that another condition is responsible for the loss of pigmentation.
Because vitiligo may be associated with pernicious anemia (a condition in which an insufficient amount of vitamin B12 is absorbed from the gastrointestinal tract) or hyperthyroidism (an overactive thyroid gland), the doctor may also take a blood sample to check the blood cell count and thyroid function. For some patients, the doctor may recommend an eye examination to check for uveitis (inflammation of part of the eye), which sometimes occurs with vitiligo. A blood test to look for the presence of antinuclear antibodies (a type of autoantibody) may also be done. This test helps determine if the patient has another autoimmune disease.