What causes squamous cell hyperplasia (lichen complex chronicus)?

Itching is one of the reactions to irritated or damaged skin.  Many things can cause the vulva to start itching.  Regardless of the original cause, if the patient rubs or scratches and damages the skin, the itching may take on a life of its own. Itching causes scratching; scratching damage of the skin; the damaged skin itches and the cycle repeats itself. Over time the skin becomes thickened and itches intensely. Stress plays a major role in this condition.