Vitiligo diagnosis

Medical history

A clinician begins by exploring when the colour changes first appeared, how quickly they developed, and whether anything seemed to trigger them, such as sunburn, skin injury, or chemical exposure. They also ask about personal or family history of autoimmune conditions like thyroid disease, type 1 diabetes, or Addison’s disease, as vitiligo may occur alongside other immune-related disorders.

Skin type matters as well, along with any whitening of hair in the affected areas. This detail can hint at changes within the hair follicles. Because vitiligo often influences confidence and day-to-day life, clinicians also discuss emotional and social impact. 

Physical examination

A detailed look at the skin sits at the heart of diagnosis. People with vitiligo usually show well-defined, pale or white patches with normal skin texture. These patches can appear anywhere, but the face, hands, wrists, elbows, knees, feet and areas around body openings are common sites.

Clinicians often use a Wood’s lamp, a type of ultraviolet light, to highlight pigment loss. Depigmented areas stand out more clearly under this light, which helps confirm the diagnosis.

During the examination, the clinician also considers other conditions that can resemble vitiligo, such as tinea versicolor or post-inflammatory pigment loss. They check for symmetry of patches, any whitening of body hair and signs of associated autoimmune issues.

In straightforward cases, the appearance of the skin alone usually allows a confident diagnosis of vitiligo. 

Skin biopsy

Most people with vitiligo do not need a skin biopsy. Doctors suggest a biopsy when the clinical picture is unclear, when the pattern is unusual, or when they need to rule out other pigment disorders.

For a biopsy, the clinician numbs a small area of skin with local anaesthetic and removes a tiny sample from an affected patch, and sometimes from nearby normal skin for comparison. A pathologist then examines the sample under the microscope.

In vitiligo, the biopsy often shows a marked reduction or absence of melanocytes, the pigment-producing cells, and a loss of melanin pigment in the outer layer of skin. In more active lesions, there may be a mild inflammatory reaction, sometimes around hair follicles. These features support the diagnosis of vitiligo, but doctors usually reserve this test for specific situations rather than using it routinely. 

Blood test

Vitiligo mainly remains a clinical diagnosis based on how the skin looks. However, blood tests often help identify or monitor associated conditions, especially autoimmune diseases, that may affect long-term health.

Doctors may request:

• Thyroid function tests, such as TSH and free T4, to look for underactive or overactive thyroid.
• Thyroid antibody tests, for example anti-TPO, if they suspect autoimmune thyroid disease.
• Vitamin B12 and folate levels, particularly if you have symptoms that suggest deficiency.
• A complete blood count or other tests if your clinician needs a broader view of your health or suspects another systemic condition.

These investigations do not diagnose vitiligo itself, but they help uncover related conditions that may require treatment and may influence how your clinician manages your skin and your overall care.