Lichen Planus

Lichen planus (LP) is an inflammatory disorder of the skin and mucous membranes with no known cause. It appears as pruritic, violaceous papules and plaques most commonly found on the wrists, lower back, and ankles. A lattice-like network of white lines called Wickham striae overlies the lesions but is most easily observed on the buccal mucosa where erosions can also be present. Drug-induced lichen planus, or lichenoid drug eruption, is frequently photo distributed but may be indistinguishable from idiopathic LP.

The natural history of LP varies significantly. The majority of patients with cutaneous lesions spontaneously clear within 1 to 2 years after initial presentation. However, recurrences are common, and residual hyperpigmentation of the skin frequently results. By contrast, oral LP is a chronic disease that may or may not remit. Drug-induced LP gradually resolves after removal of the causative medication.