Its etiology is still unknown, although infectious mechanisms and vitamin and minerals deficiencies have been implicated, a causal relationship has not been recognized. However, excessive and unprotected sun exposure is considered the most important causal factor involved. However, studies from stratum corneum from of PA lesions have described defects in hygroscopicity and water-holding capacity detectable by water sorption-desorption test, this suggests that the condition is similar to a dermatitic change and its hypopigmentation may be consequence of a postinflammatory mechanism.