Lichen planus: an update and review.

Lichen planus (LP) is a papulosquamous eruption of the skin, scalp, nails, and mucous membranes. Although LP is more common in adults, it has become an established pediatric disorder. Its classic presentation is characterized by 4 p's: purple, polygonal, pruritic papules. Histopathologic examination reveals characteristic interface dermatitis. Although its pathogenesis is not fully understood, there is evidence that an imbalance of immunologic cellular reactivity is central. Lichen planus usually resolves within a few months. Treatment that primarily consists of topical and/or oral steroids will expedite recovery and alleviate symptoms. Resolution of this cutaneous disease often is accompanied by postinflammatory hyperpigmentation. Long-term sequelae of LP in the pediatric population are rare, but cutaneous atrophy and pterygium unguis may occur.