What is "lichen planus"

n. an eruption of shiny flat-topped purplish (usually itchy) papules on the wrist and forearms and thighs [syn: lichen ruber planus]

Lichen planus (LP) is an uncommon disease of the skin with a prevalence reported between 0.1–0.3% in women and men respectively. The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms.

The term lichenoid reaction (or lichenoid lesion) refers to a lesion of similar or identical histopathologic and clinical appearance to lichen planus (i.e. an area which looks the same as lichen planus, both to the naked eye and under a microscope). Sometimes dental materials or certain medications can cause a lichenoid reaction. They can also occur in association with graft versus host disease.