Is lichen simplex chronicus a disease or an abnormal response to itching?

It's a condition: The skin condition (not disease) is caused simply enough by chronic scratching which comes about usually by chronic itching and it's a vicious cycle. The itching can be caused by things such as insect bites, psoriasis, or anything else that leads to a dermatitis. Treatment is stop scratching. Easier said than done in most cases. Here's a good link to help you: http://www.Nlm.Nih.Gov/medlineplus/ency/imagepages/1562.Htm.