Chronic Spontaneous Urticaria (CSU)

Authors: Reid Oldenburg, MD, PhD, FAAD and Kathleen Luskin, MD

Editor: Kathleen Luskin, MD

Overview

- Also known as ‘Chronic Idiopathic Urticaria’ (CIU)

- Definition: urticarial wheals and/or angioedema for ≥ 6 weeks without identifiable etiology [1, 2]

o Wheal: variably sized pruritic lesions with central pallor and surrounding erythema,

with each lesion lasting < 24H and healing without residual scar, bruise, necrosis or

dyspigmentation

▪ Some may have pricking or burning sensation in addition to, or rather than,

pruritis

o Angioedema: erythematous or skin-colored deep swelling involving lower dermis and subcutis or mucosa; may be pruritic, tingly, burning

▪ Resolution is slower than wheals, and may take up to 3 days

- Impacts 0.1-4.4% of the general population, onset usually 30s-50s years, female-predominant [2, 3]

- Typical duration 1.5-5 years [2-4], but can be long-standing in some individuals

o Remission at 1 year 17%; 5 years 45%; 20 years 73% [5]

o Autoimmune subtype may be more persistent [2]

- Often worse in the evening [2]

- Presentation may be urticaria-predominant, angioedema-predominant (least common), or

combination of both (approximately 40-60%) [2-4, 6]

- No identifiable trigger (drug, food, environment, physical, underlying disorder) is found that explains all episodes; may have comorbid inducible/physical urticaria (1-45%) [3, 7]. o

Most common comorbid inducible urticarias: symptomatic dermographism, delayed

pressure, cold and cholinergic urticarias [7]

o CSU and inducible urticarias onset coincide in 2/3 of cases [7]

o Individuals with CSU and comorbid inducible urticarias may be younger, have earlier

disease onset, longer disease duration, worse quality of life (QOL), lower incidence

of autoimmune features (concomitant autoimmune disorder, eosinopenia, low IgE,

high anti-TPO IgG), and more atopy [7]

o May have multiple triggers and/or need for multiple triggers to be present at the same time (ex. food-dependent and/or exercise-induced phenomena) [8-10]