Hypertrophic lichen planus lesions on the ankle of a 33 year old African American female patient. Lichen planus is a common inflammatory disorder of the skin and mucous membranes characterised by itchy, flat-topped bumps. In the hypertrophic form, the rash develops into scaly plaques. The cause is unknown. Treatment is with topical corticosteroids alongside antihistamines to reduce itching. Most cases of lichen planus disappear within two years.