A chronic condition that may cause inflammation of the skin of the legs, trunk, arms, wrists, scalp, penis, lining of the mouth, vagina, toe-nails and fingernails. The rash comes and goes and is itchy, mildly swollen and red or purplish. It is most common in adults over 40, but can affect people of any age. The cause of this disorder is not known but in some cases it seems to be triggered by viral hepatitis (liver inflammation) or allergic reactions.