Lichen Planus - Cause

Cause

See also: List of human leukocyte antigen alleles associated with cutaneous conditions

Lichen planus is not contagious and does not involve any known pathogen. Some lichen planus-type rashes (known as lichenoid reactions) occur as allergic reactions to medications for high blood pressure, heart disease and arthritis, in such cases termed drug-induced lichenoid reactions. These lichenoid reactions are referred to as lichenoid mucositis (of the mucosa) or dermatitis (of the skin). Lichen planus has been reported as a complication of chronic hepatitis C virus infection and can be a sign of chronic graft-versus-host disease of the skin (Lichenoid reaction of graft-versus-host disease). It has been suggested that true lichen planus may respond to stress, where lesions may present on the mucosa or skin during times of stress in those with the disease. Lichen planus affects women more than men (at a ratio of 3:2), and occurs most often in middle-aged adults. The involvement of the mucous membranes is seen frequently and usually is asymptomatic, but occasionally, LP can be complicated by extensive painful erosions. Lichen planus in children is rare.

Reactions to amalgam fillings may contribute to the oral lesions very similar to lichen planus, and a systematic review found that many of the lesions resolved after the fillings were replaced with another material.

Lichen planus can be part of Grinspan's syndrome.