Urticaria is an inflammatory skin disorder that may occur in isolation or associated with angioedema and/or anaphylaxis. Clinically, it is characterized by the presence of smooth, erythematous or blanching, itchy swelling, called wheals or hives, which greatly vary in size and shape and last less than 24 h before fading to leave normal skin. Urticaria is the consequence of mast-cell degranulation that can be caused by immunological or non-immunological mechanisms. From a clinical point of view, many skin conditions can mimic urticaria and their recognition is mandatory for a correct management and therapeutic approach. We have reviewed all of the main relevant studies which addressed differential diagnosis of urticarial, published until December 2022. The National Library of Medicine PubMed database was used for the electronic research. The present review offers a clinical narrative overview, based on the available literature, of the principal skin disorders that can be misdiagnosed as urticaria (mainly autoinflammatory or autoimmune disorders, drug-induced reactions, and hyperproliferative diseases). The aim of this review is to provide clinicians a useful tool for correctly suspecting and identifying all of these conditions.
Keywords: auto-inflammatory syndromes; autoimmune disorders; differential diagnosis; drug-related eruptions; hyperproliferative diseases; urticaria.