Lichen sclerosus's pathogeny, the most frequent vulvar dystrophy predominant at the start of menopause, is still enigmatic. Its repercussions on the functional level can be disabling. Its clinical sides include atrophy and sclerosis. The evolution of the past towards great atrophies (kraurosis vulvae) may today be prevented by early diagnosis and treatment (essentially dermocorticoïde). Even if the risk of degenerescence is low, it's not negligible and these patients must be put under steady surveillance.