Physical urticaria.

The physical urticarias are a heterogeneous subgroup of chronic urticarias in which wheals can be reproducibly induced by different specific physical stimuli such as cold, heat, pressure, vibration, or sunlight. Physical urticarias comprise up to 25 % of chronic urticarias and occur more frequently in young adults. Symptoms, i.e. wheal and flare responses or angioedema, are usually limited to the skin areas exposed to the eliciting stimulus. However, generalised urticaria with variable extracutaneous manifestations can also occur. Some patients may also present with more than one physical urticaria. Skin lesions in physical urticaria result from mast cell activation and mediator release. The mechanisms by which physical stimuli activate skin mast cells are not fully understood. Because of this, trigger avoidance and symptomatic treatment are key therapeutic concepts for physical urticarias. Identification of the inducing physical trigger, including its individual thresholds, is necessary for an effective therapy. Here, we have summarized clinical features, diagnostic workup and therapy options for physical urticarias.