lichen planus

from The Century Dictionary.

• noun in pathology, a form of lichen, occurring on the forearm and on parts of the body which are constricted by the clothing, in which the papules are flattened and smooth and are the seat of much itching.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an eruption of shiny flat-topped purplish (usually itchy) papules on the wrist and forearms and thighs