Lichen plan et dermatoses lichénoïdes

Lichen planus is a chronic itching dermatosis of the adult, characterized by shiny flat violaceous polygonal papules. It may affect any part of the body surface, but it is most likely to appear on the extension part of the limbs. Mucous-membrane lesions are very common. Atypical forms are usual. Histological features are a superficial band-like infiltrate of lymphocytes in the superficial dermis with necrotic keratinocytes at the dermo-epidermal junction. Cutaneous forms usually disappear within 6 to 12 months, but mucous membrane lesions have a more chronic evolution, and can have a malignant potential. The aetiology remains unknown, immunological disorders are probably involved. Local or systemic corticosteroids, retinoids and PUVA therapy are the main treatments, but oral corticotherapy still need to be evaluated.