L'urticaire chronique n'est qu'exceptionnellement une maladie systémique

Chronic urticaria (CU) is an inflammatory skin disease which expression may be under the combined influence of several co-factors in predisposed individuals. There is great confusion between the cause of the disease (supposed to be a mast cell fragility, partly constitutional) and the aggravating factors. About 1% of UC are associated with systemic disease (mainly autoimmune disorders, dysglobulinemia and other hematological diseases). The clinical features are most often very different from those of a common UC except when it becomes severe with a pseudosystemic misrepresentation. The diagnostic tests, including pathology, can also be misleading, wrongly directing to a systemic disease, especially in steroid-dependant UC or delayed pressure urticaria. Great caution and long-term follow up are therefore required before asserting the diagnosis of systemic urticaria.