How long can lychin planus last and how can u get this? i had a major op and it appeared a few months after

Up to two years.: Lichen planus seems to be an auto-immune skin disease of unknown cause. It can affect various parts of the skin, mucus membranes (oral, vaginal) and nails. It can be diagnosed definitively by biopsy. Often not symptomatic, but can cause itching or burning. No known cure, but topical or systemic cortisone may help. May last up to two years. 1/5 cases recur.