Algorithms in allergy: Diagnosis, pathogenesis, and treatment of chronic spontaneous urticaria

Chronic urticaria, defined as having urticaria for over 6 weeks, is divided into two categories; namely, inducible urticaria and chronic spontaneous urticaria (CSU). Inducible urticarias have an initiating stimulus, often “physical”, and actually occur intermittently, but the total duration of symptoms can encompass many years.

CSU is more typically chronic, with urticarial lesions most days of the week, and has no exogenous cause. An algorithm for the diagnosis of CSU is shown in Figure 1. Angioedema typically associated with CSU affecting face, extremities, genitalia, lips, tongue, and rarely pharynx, but not the larynx.

Thus risk of asphyxiation is nil. The disorder is strongly associated with autoimmunity. The best studied involves IgG antibody to the IgE receptor1 which cross-links unoccupied IgE receptors of mast cells and basophils and activates these cells to cause secretion of histamine, leucotrienes, cytokines, and chemokines.

Complement is activated, and the release of C5a augments the mast cell secretion.2 There is a second scenario in which patients have IgE antibody to a large variety of autoantigens3 including thyroperoxidase and interleukin 24, although which are pathogenic is not yet clear. Clinically, other autoimmune disorders may be present.

The most prominent is Hashimoto's thyroiditis. Antithyroid antibodies (i.e., IgG antimicrosomal antigen and IgG antithyroglobulin) are seen in 25% of patients regardless of thyroid status. Total IgE is elevated within this population although much less so than in asthma or atopic dermatitis. Low or very low IgE levels may be seen, and such patients are less responsive to omalizumab.4

CITA DEL ARTÍCULO  Allergy. 2024 Apr 1. doi: 10.1111/all.16113