Chronic urticaria as a systemic disease

Urticaria is one of the most common diseases seen in everyday dermatologic practice, characterized by the development of wheals, angioedema, or both. While acute urticaria is mostly related to allergic or pseudoallergic reaction to food, drugs, or infections, chronic urticaria is a more complex disease with different additional ethiopathologic mechanisms and evoking factors. While urticaria is an undisputed disease of the skin, growing evidence supports, like in other dermatologic diseases, the concept of urticaria as a systemic disease with clinical symptoms and signs predominantly presenting on the skin. In this review, we describe the evidence and association between chronic urticaria and a variety of disorders, such as autoimmune diseases, atopy, infections, metabolic conditions, and neoplastic disorders. Beyond the mechanistic association, the possible common underlying pathomechanisms, such as systemic immunologic processes, are discussed.