Classification and Treatment of Urticaria: A Brief Review

Kjetil Kristoffer Guldbakke, MD; Amor Khachemoune, MD, CWS

Disclosures

Dermatology Nursing. 2005;17(5):361-364. 

In This Article

Introduction

Urticaria affects 10% to 25% of the population at some point in their life (Henderson, Fleischer, & Feldman, 2000). It is characterized by short-lived swellings of the skin, mouth, and genitalia related to a transient leakage of plasma from small blood vessels into the surrounding connective tissues. Urticaria may present with superficial swellings of the dermis called wheals or deeper swellings of the dermis, subcutaneous, or submucosal tissues known as angioedema. Wheals are typically itchy with a pale center due to edema, maturing into pink superficial plaques that usually resolve within 24 hours without sequela. Areas of angioedema tend to be pale and painful, and last longer than wheals, and may also affect the mouth and rarely the bowel.

Classification

Urticaria may be acute or chronic. As opposed to acute urticaria, chronic urticaria is defined by recurrent episodes occurring at least twice a week for 6 weeks (Grattan, Sabroe, & Greaves, 2002). Urticaria occurring less frequently than this over a long period is better called episodic, as it is more likely to have an identifiable environmental trigger. All chronic urticaria implicitly goes through an acute stage (<6 weeks). Although many classification systems exist, a concise clinical classification is included in Table 1 . Skin conditions to be considered for differential diagnosis are summarized in Table 2 .

The Role of Mast Cells

Mast cells are the primary effector cell of urticaria. They are widely distributed in the skin, intestinal mucosa, alveolar wall, and nasal mucosa, and have high-affinity IgE receptors (FcRI). Mast cells contain inflammatory mediators, of which histamine is the most important, in addition to various cy tokines modulating the inflammatory response. Degranulation occurs either by an IgE-mediated (type I) hypersensitivity reaction, which is the major pathway for acute ur ticaria or by several non-immunologic stimuli independent of FcRI.

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