[Systemic urticarias].

Systemic urticaria remains a challenge in terms of etiology, investigation and management. Most of cases are urticarial vasculitis consequence of inflammatory injury of capillaries and postcapillary venules in the skin. If hypocomplementemic urticarial vasculitis syndrome is a classical cause, the majority of patients have an underlying systemic disease like systemic lupus erythematosus, Sjögren's syndrome, mixed cryoglobulinemia, Still disease or cancer. Others systemic urticaria have been reported without clearly evidence of vasculitis like in primary or acquired angioedema, hereditary periodic fever syndromes and in some thyroiditis. Diagnosis needs a step to step procedure. Treatment depends the underlying disease. Some patients respond to nonsteroidal antiinflammatory drugs, some other need corticosteroids or immunosuppression. If urticarial vasculitis seems isolated in the absence of chronic obstructive pulmonary disease, antihistamines, nonsteroidal antiinflammatory drugs, colchicine, dapsone or hydroxychloroquine must be first used.