Hives but no urticaria—what could it be?

Urticaria is a common inflammatory dermatosis characterized by transient, usually intensely itching wheals mediated by mast cells. Urticarial lesions can also be mimicked by other skin diseases. Differential diagnoses of urticaria should be considered if the single urticarial skin lesion persists for more than 24 h, if hyperpigmentation, scaling, or blistering occurs, if the lesions are not itching, or if fever or arthralgias are reported. In these cases, histologic examination and thorough serologic diagnostic may help to differentiate other dermatoses, such as vasculitis, autoimmune bullous skin diseases, drug reactions, or autoinflammatory syndromes. This article summarizes common differential diagnoses of urticaria.