The current most widely accepted theory causing vitiligo is autoimmunity. Autoimmunity means the body's own immune system attacks its own cells, and in the case of vitiligo, the destruction of melanocytes by the body's own antibodies. That is why vitiligo patients are screened for other autoimmune conditions like Hashimoto's thyroiditis, diabetes mellitus, Addison's disease, alopecia areata, etc.

Melanocytes reside at the base of the skin, generating melanin which gives colour to the skin. When skin is exposed to UVA & UVB (in sunlight), there is DNA damage in the skin which triggers increased production of melanin that absorbs UV rays and protects the skin from further damage, hence the tan. That is why there is such high incidence of skin cancer in the light-skinned e.g Caucasians as there is less protective melanin in their skin. That is also why we should not sunbath / go for tanning beds. Look for sunblocks against both UVA and UVB. Avoid the sun from 10am to 4 pm.

In vitiligo, treatment is aimed at increasing melanin production from melanocytes at the borders of the lesion as well as spared melanocytes not affected by depigmentation, hence the UV phototherapy.
Topical steroids are used to suppress the local skin immune system so that there is no further destruction of melanocytes. Long term topical steroid use is associated with skin thinning and systemic effects. Hence, topical pimecrolimus is recommended as substitute.

Other treatments include:
- skin grafting
- laser
- protect against sun