I was diagnosed two months ago with lichen planus. I have the rash on my ankles, inner wrists, underside of my tongue and inside the walls of my mouth. For the itch on my ankles and wrist I rub three things on the rash that immediately stop the itch. First I rub tea tree oil on it followed by olive oil (organic) and baking soda. This is not a cure for lichen planus only a treatment for the itch.
Diet is key to controlling the intensity of the rash. Basically you have to eliminate all sugars (including honey and agave) dont eat any bread or white rice no processed food etc. you have to get super clean on your diet. I have since gone 90% raw which helps alot.
I got rid of the bumps inside my mouth and the painful lesions on the underside of my tongue by gargling with my urine. I know this might be hard to believe but google "urine therapy" and you will see that urine has a long and ancient history of being used as a medicine.