Lichen planus is an inflammatory condition that can produce specific symptoms on
the skin, nails, scalp, mouth
tissues and genitals. On the skin, it produces a reddish-purple, itchy rash with flat bumps or a white, lacy appearance. In the mouth, it can produce a burning sensation, sore gums, tenderness when eating or toothbrushing and a metallic taste. Lichen planus isn't communicable. Theories about the cause of the disease propose it is an allergic or autoimmune response.