Reactivated urticaria pigmentosa.

Urticaria pigmentosa is a rare dermatologic disorder characterized by cutaneous mastocytosis either in isolated or diffuse forms. The disease usually occurs before age 4, but does occur in adulthood. When it occurs in adults, it is associated with a higher incidence of systemic involvement and malignancy. We describe a case of reactivated urticaria pigmentosa temporally associated with acute contact dermatitis in an adult. We describe a practical screening method for systemic involvement and an approach to treatment.