A chronic, recurrent, pruritic inflammatory disorder of unknown etiology that affects the skin and mucus membranes. It presents with rashes and papules that tend to resolve spontaneously. It may be associated with hepatitis C. Certain drugs that contain arsenic or bismuth are associated with reactions mimicking lichen planus. The disease is lichen planus (MONDO_0006572, a Monarch Disease Ontology entry). Also known as: lichen ruber planus, lichen, ruber planus.