001899 - Efficacy of Omalizumab in Isolated Angioedema as An Uncommon Phenotype of Chronic Spontaneous Urticaria (one-centre experience)

Chronic spontaneous urticaria (CSU) is defined by the occurrence of recurrent wheals and/or angioedema persisting for more than six weeks. Although omalizumab is an established treatment for antihistamine-refractory CSU, data on its effectiveness in patients presenting exclusively with angioedema, without wheals, remain scarce. This clinical phenotype represents a diagnostic and therapeutic challenge and is frequently underrepresented in randomized controlled trials. We would like to present effectiveness and safety of omalizumab in patients with CSU presenting as isolated angioedema.

We report a case series of six patients (five females, one male) with CSU manifesting as isolated angioedema accompanied by severe pruritus. Hereditary angioedema was excluded in all patients. All individuals were unresponsive to up-dosed (fourfold) second-generation H₁-antihistamines and subsequently received omalizumab as second-line therapy at a standard dose of 300 mg subcutaneously every four weeks.

The mean age of patients was 42.7 ± 13.8 years, with a mean age at symptom onset of 35.8 ± 11.9 years. Allergic comorbidities were present in five patients (allergic rhinitis, allergic conjunctivitis, bronchial asthma). Other comorbidities included hypertension (n = 1), metabolic syndrome (n = 1), gastroesophageal reflux disease (n = 1), acne (n = 1), and anxiety disorder (n = 1). Laboratory abnormalities included elevated C-reactive protein (n = 2), elevated baseline tryptase (n = 1), antinuclear antibody positivity (n = 1), and selective IgG₂ deficiency (n = 1). Following initiation of omalizumab, all patients demonstrated a marked reduction in angioedema attack frequency and pruritus, achieving complete or near-complete disease control after the first dose and complete disease control during treatment. Four patients relapsed after treatment discontinuation and required reinitiation of omalizumab. The mean number of omalizumab treatment cycles was 4.0 ± 2.7. Treatment was well tolerated, with no adverse events observed.

Our data highlight isolated angioedema as a clinically relevant CSU phenotype that responds rapidly and consistently to omalizumab. These findings underscore the importance of recognizing isolated angioedema as part of the CSU spectrum and support the use of anti-IgE therapy in antihistamine-refractory patients, even in the absence of wheals.