Chronic Spontaneous Urticaria: The Devil's Itch

Chronic urticaria is defined as the presence of urticaria for a period exceeding 6 weeks, assuming symptoms for most days of the week. It is divided into chronic inducible urticarias and chronic spontaneous urticaria, previously termed chronic idiopathic urticaria. The latter designation emphasizes that patients can experience urticaria independent of any exogenous stimulus even if one can define circumstances that may worsen symptoms. A search for such an external “cause” is fruitless because the underlying abnormality is “intrinsic,” whether it is autoimmune, or some unknown process. Approximately 40% of patients with chronic spontaneous urticaria report accompanying episodes of angioedema, whereas 10% have angioedema as their primary manifestation. In most cases, it is a self-limiting disorder, persisting for 2 to 5 years in most cases, although 20% of patients suffer for more than 5 years. The treatment that has evolved is largely empiric, based on double-blind, placebo-controlled studies whenever possible, but is not yet targeted to any particular pathogenic mechanism. In this article, we review the current status regarding pathogenesis, discuss the diagnostic workup, and update the approach to treatment including consideration of published guidelines, our own experience, and guideline updates that are being prepared.

Introduction

Chronic urticaria is defined as the presence of urticaria for a period exceeding 6 weeks, assuming the presence of symptoms for most days of the week. It is divided into chronic inducible urticarias (also called physical urticarias) and chronic spontaneous urticaria (CSU), previously termed chronic idiopathic urticaria.1, 2 Chronic inducible urticarias are identified on the basis of history of a consistent stimulus that initiates lesions, which are typically short-lived and fleeting, lasting a few minutes up to 2 hours. When biopsied, there is no cellular infiltrate. In contrast, the term CSU emphasizes that patients can experience urticaria independent of any exogenous stimulus even if one can define circumstances that may worsen symptoms. Thus, a search for such an external “cause” in CSU is a fruitless effort because the underlying abnormality is “intrinsic.” Approximately 40% of patients with CSU will report accompanying episodes of angioedema or deeper swelling of dermal or mucosal tissues, whereas 10% have angioedema as their primary manifestation.3, 4 In most cases, it is a self-limiting disorder, persisting for 2 to 5 years in most cases, although 20% of patients suffer for more than 5 years.5, 6, 7

The treatment for CSU that has evolved is based on double-blind, placebo-controlled studies whenever possible, but is not yet targeted at any particular pathogenic mechanism. Although the efficacy of omalizumab in disease has implicated IgE and IgE receptors in disease pathogenesis, a clear biomarker that segregates responders from nonresponders remains elusive. In this article, we will review the current status regarding pathogenesis, discuss what are the essentials of a diagnostic workup, and update the approach to treatment including consideration of published guidelines, our own experience, and guideline updates that are being prepared.