
Abstract
Chronic urticarial rash, mostly due to chronic spontaneous urticaria (CSU), is seen in up to 1 – 4% of the general population. Urticarial vasculitis (UV) and autoinflammatory syndromes, i.e., cryopyrin-associated periodic syndromes (CAPS) and Schnitzler syndrome (SchS), can mimic CSU-like rash but represent rare disorders with systemic symptoms including fever, headache, conjunctivitis, and arthralgia. Clinical and laboratory features can point to the presence of any of these diseases in patients initially presenting with chronic urticarial rash. These include long-lasting wheals (> 24 hours), lesional burning, systemic symptoms, and/or increase in inflammatory markers (e.g., C-reactive protein, serum amyloid A, and/or S100A8/9).





