A Comprehensive Approach to Urticaria: From Clinical Presentation to Modern Biological Treatments Through Pathogenesis.

Urticaria is characterized by the cutaneous presence of wheals (hives), angioedema or both. Acute and chronic urticaria are distinguished based on a duration of less or more than 6 weeks. Chronic urticaria can be further classified into a spontaneous form and several inducible types triggered by specific external stimuli. Lifetime prevalence of urticaria may be up to 20%, with the acute form being way more common than the chronic one. Exacerbating factors (e.g. infections, drugs, food) and immune system alterations have been investigated as main triggers of mast cell activation, which in turn leads to increased vascular permeability and extravasation of inflammatory cells. While diagnostic workup is focused upon history taking, several emerging biomarkers correlate with severity and/or prognosis of the disease and can be necessary to differentiate chronic spontaneous urticaria from other disorders, such as vasculitis and autoinflammatory diseases. Treatment of acute urticaria is based upon H1 antihistamines and short courses of steroids. While H1 antihistamines are also used in chronic spontaneous urticaria, omalizumab is the standard of care in patients who are unresponsive to these. Recently, several new drugs have entered clinical trials to offer a therapeutic possibility for patients unresponsive to omalizumab. Numerous target molecules, such as mediators of mast cells activation, are under investigation. Amongst these, new anti-IgE therapies and possibly IL-5 pathway blockade seem to have reached enough data to move to advanced clinical trials.