The most common form of vulvar dermatose is the lichen sclerosus. More frequent after menopause, it can be observed at all ages, even in childhood. Vulvar lichen sclerosus manifests usually by a vulvar pruritus and (or) orificial dyspareunia, however in 15% of cases it remains asymptomatical. The lesions can extend to all the vulva, giving it a very particular pearly white aspect, or remain localized as a "leucoplasia", requiring biopsy to confirm the diagnosis. It is mostly the hyperplastic lichen sclerosus (consisting of a marked epithelial hyperplasia) which risks degeneration. In case of non-response to a strong local steroid therapy, high risk clinical cases must be pointed out, treated and biopsied. A biopsy must be done in thick leucoplastic areas which are coarse, steady and rebellious to treatment, specially on ulcered zones without any tendency to healing or palpable infiltrated lesions.