ALLERGIC DERMATOSIS AND URTICARIA (J RING, SECTION EDITOR) Physical Urticaria Marina Abajian & Agnieszka Mlynek & Marcus Maurer Published online: 1 June 2012 # Springer Science+Business Media, LLC 2012 Abstract The physical urticarias are a heterogeneous sub- group of chronic urticarias in which wheals can be repro- ducibly induced by different specific physical stimuli such as cold, heat, pressure, vibration, or sunlight. Physical urti- carias 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, gen- eralised urticaria with variable extracutaneous manifesta- tions 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 re- lease. The mechanisms by which physical stimuli activate skin mast cells are not fully understood. Because of this, trigger avoidance and symptomatic treatment are key thera- peutic concepts for physical urticarias. Identification of the inducing physical trigger, including its individual thresh- olds, is necessary for an effective therapy. Here, we have summarized clinical features, diagnostic workup and thera- py options for physical urticarias. Keywords Physical urticaria . Urticaria factitia . Symptomatic dermographism . Delayed pressure urticaria . Cold contact urticaria . Heat contact urticaria . Solar urticaria . Vibratory urticaria/angioedema . Angioedema Introduction Physical urticaria is a group of acquired diseases character- ized by a common and distinctive clinical pattern, i.e. the induced development of itchy wheal and flare type skin lesions and/or angioedema. These symptoms are induced by exogenous physical triggers specific to the physical urticaria subtype: mechanic (friction, pressure and vibra- tion), thermal (cold and heat), and electromagnetic (solar) radiation (Table 1). In all physical urticarias, skin sites of trigger exposure can react with wheals and angioedema, with the exception of urticaria factitia (where only wheals are found and angioedema is absent) and pressure urticaria (with only angioedema but no wheals). Little is known about the prevalence of physical urtica- rias. Up to 0.5 % of the population is thought to suffer from chronic physical urticaria, and these conditions comprise up to 15—25 % of chronic urticarias [1]. Physical urticarias often occur in combination with other forms of chronic urticaria, e.g. spontaneous urticaria and/or another subtype of inducible urticaria [2]. The underlying causes of physical urticaria remain unknown. They are diagnosed on the basis of patients’ case histories and on the results of skin provo- cation testing. Patients who are suspected of having physical urticaria should be tested for every potentially relevant trigger [3••]. Since patients display a large range of individ- ual trigger thresholds, which may vary with time and ther- apy, trigger thresholds should be determined in each patient who is diagnosed with physical urticaria, and must be re- peated thereafter. This helps patients to prevent symptoms in daily life, and helps treating physicians to optimize the Marina Abajian and Agnieszka Mlynek contributed equally. M. Abajian : A. Mlynek : M. Maurer (*) Department of Dermatology and Allergy, Allergie-Centrum-Charité/ECARF, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany e-mail: marcus.maurer@charite.de M. Abajian e-mail: marina.abajian@charite.de A. Mlynek e-mail: agnieszka.mlynek@charite.de Curr Allergy Asthma Rep (2012) 12:281–287 DOI 10.1007/s11882-012-0269-0