Lichen Planus

Anyone know anything about Lichen Planus ? reasons for why it begins ? found some stuff about it but seems they do not know what causes it, some articles say stress, weather changes, some say it is precancerous. If the cancerous part is true, is it reversible? treatable? or what ?
Also how about strep, staph and yeast contributing to cancer? I am bored at work, it is raining and my mind is wandering about these issues.