Figure 1

The diagnostic pathway of Urticaria. Although allergy is a rare cause of CSU an allergy screening test should be considered in CSU patients with intermittent symptoms and a suggestive history. Chronic persistent bacterial, viral parasitic and fungal infections that may trigger urticarial symptoms in patients with CSU should be considered, only according to the patient’s history [7]. Total immunoglobulin count, antinuclear factor and skin biopsy should be considered in patients with single hives that lasts >24 hours, to rule out vasculitis or Schnitzler syndrome [8]. In Physical Urticaria the routine diagnosis is mainly aimed at the identification of the subtype of the urticaria through the appropriate physical stimulation tests and to the determination of trigger thresholds [7]. Since CU in children may be associated with autoimmune diseases, like celiac or thyroid disease, some Authors suggest to screen for them [9]. 30-50% of patients with CSU produce an immunoglobulin IgG type autoantibody against either the high affinity receptor FcERIα or IgE. However, the utility of the Autologous Serum Skin Test (ASST) remains unclear in identifying a distinct subgroup of patients with CU and in predicting natural history and response to treatment. So, current evidence does not support routine performance of this test in patients with CU [26]. Some other conditions should be considered in the diagnostic process mainly when an immunocomplex-induced disease is suspected. These include serum sickness or autoimmune diseases. When isolated angioedema is present, the assessment of C4 and C1 esterase inhibitor levels should be performed [8].