Urticaria and angioedema: a clinical spectrum.

Abstract

The objective of this review is to give the reader a global insight into the spectrum of urticaria, focusing on differential diagnosis and pathogenic mechanisms. This review will define the role of the mast cell, explore a possible autoimmune basis for urticaria, and examine the purported role of food allergy in chronic urticaria. Last, the work-up and treatment of urticaria will be discussed in the context of the histologic diagnosis. The relevant past medical literature will be reviewed in the context of new and novel research into the mechanisms of chronic urticaria. Urticaria can be classified histopathologically into the following three categories: (1) neutrophilic vasculitis, (2) polymorphous perivascular infiltrate, and (3) sparse perivascular lymphocytic infiltrate. Each of the above histologic patterns correlates with a distinct clinical entity and the work-up and treatment of urticaria will be related to each of the above histologic types. Urticaria and angioedema are frustrating problems for both physicians and their patients; however, the problem can best be approached by considering urticaria as a symptom that may be part of a larger clinical spectrum. The physical examination and medical history remain the two most important pieces of information. The allergist frequently overlooks the value of a skin biopsy as an aid in sorting out the pathophysiology of urticaria and the biopsy results may help to classify urticaria into subgroups which respond differently to treatment.