any skin (dermatological) disorder in which psychological factors are believed to play an important role. In some cases (e.g., hives, psychogenic pruritus), the disorder appears to be caused or exacerbated by psychological factors; in others (e.g., acne, psoriasis, eczema, dermatitis), there is a predisposition to the condition, which is precipitated by stress factors (see diathesis–stress model).