Lichen planus

Lichen planus is an idiopathic inflammatory skin disease of unknown etiology. Lichen planus can affect the skin, mucous membranes (especially the oral mucosa), scalp, nails, and external genitalia. When it affects the skin, it commonly occurs on the inner sides of the limbs but can also be generalized. There is no difference in prevalence between males and females. It is less common in the elderly and children, with approximately two-thirds of cases occurring between 30 and 60 years of age.