Acquired cold urticaria: clinical picture and update on diagnosis and treatment.

Acquired cold urticaria (ACU) is a frequent subtype of physical urticaria that is caused by the release of proinflammatory mast cell mediators after cold exposure. Although the underlying causes of ACU still remain to be clarified in detail, a wide range of diseases has been reported to be associated with ACU. This review gives an overview of the clinical picture, the differential diagnoses, diagnostic tests and the aetiology of ACU, and summarizes current and novel therapeutic options based on the current literature.