An overview of delayed pressure urticaria with special emphasis on pathogenesis and treatment.

Delayed pressure urticaria (DPU) is a physical urticaria characterized by the development of deep swellings at sites of pressure application on the skin. Etiopathogenesis of DPU is still unknown, although the available evidence suggests the involvement of mast cells through non-immunologic mechanisms and the role of several mediators beyond histamine, such as proinflammatory cytokines. The management of DPU is complex, also considering that prevention is very difficult and DPU frequently coexists with chronic "idiopathic" urticaria. Moreover, H1-antihistamines, which are the mainstay of treatment for common urticaria, usually provide less satisfactory results as compared with other urticarias. Therefore, numerous treatment alternatives have been proposed for severe refractory cases, such as oral or topical corticosteroids and various drugs with anti-inflammatory effects.