Lichen planus is a chronic dermatosis which occurs preferentially inmiddle-aged adult : it occurs in 2/3 of cases between 30 and 60 years and it is rare at the extreme ages of life. It affects both women and men. It concerns approximately 1% of the population.

It appears, in its typical form, as itchy scaly skin lifts that itch, located on wrists and ankles notably. It can also affect the oral and genital mucous membranes. A particular form concerns the scalp (lichen planus pilaris).

Does lichen planus have a cause?

La cause of lichen planus is not known ; we consider that it could be a autoimmune process but we lack evidence.

other diseases are associated with lichen planus: thymoma, Castelman’s disease, Biermer’s disease, Addison’s disease, alopecia areata, diabetes, ulcerative colitis …

The association with a liver disease chronic (primary biliary cirrhosis, hepatitis C, etc.) seems to be more frequent in erosive mucosal damage the lichen plan.