Chronic Urticaria and Recurrent Angioedema: Clues to the Mimics.

Urticaria and angioedema are experienced by up to 1 in 5 people, usually the result of common allergen or medication triggers and infections. Similarly, the majority of recurrent angioedema has an exogenous trigger, for example, angiotensin converting enzyme inhibitors, or is hereditary (type 1 and 2 hereditary angioedema); chronic spontaneous urticaria are most often autoimmune or autoallergic in routine clinical practice. There are, however, several skin and systemic conditions that can imitate the clinical appearance of either angioedema or urticaria, whereas there are several uncommon conditions that have chronic urticaria and/or recurrent angioedema as part of their disease manifestations. Correct diagnosis is paramount to ensuring subsequent tailored therapy for many of these conditions, and in many instances, diagnostic delay can be several years with morbid consequence. In this grand rounds article, we present 2 illustrative clinical cases as the backdrop to discussing a practical diagnostic approach for clinicians to recognize copycat phenotypes and "red flags" that should prompt further investigation of several uncommon mimics. We highlight key diagnostic features, epidemiology, and management for mimics where treatment is distinct from the common phenotypes of recurrent angioedema and chronic urticarias.