Co-existence of chronic spontaneous urticaria with atopic dermatitis: clinical and immunological perspectives.

Background: Chronic Spontaneous Urticaria (CSU) and Atopic Dermatitis (AD) are both immune-mediated inflammatory skin disorders that often co-exist with other atopic conditions such as asthma and allergic rhinitis. Their shared immunopathological pathways raise the question of a possible interrelationship. Objective: To evaluate the prevalence, clinical features, and immunological profiles of AD in patients with CSU and to explore implications for diagnosis and treatment. Methods: 425 CSU patients treated in Northern Israel between 2021 and 2024, were retrospectively analyzed. Disease activity was assessed using the Urticaria Activity Score-7 (UAS7) and Investigators' Global Assessment (IGA) for AD. The prevalence of asthma, total serum IgE levels, and therapeutic responses were evaluated. Results: Among the 425 CSU patients, 42 (10%) were also diagnosed with AD. Co-morbid patients had a higher frequency of asthma (40%) and high total IgE levels (67%) compared to CSU-only patients. A substantial subset of co-morbid cases required biologic treatments with Dupilumab, offering benefit in AD-dominant cases unresponsive to Omalizumab. Severe CSU was more prevalent in the CSU + AD group (though the prevalence was not statistically significant). Conclusion: CSU and AD frequently co-exist, likely due to overlapping T-cell-mediated immunopathogenic mechanisms. High total IgE and asthma comorbidity may indicate an underlying AD component in CSU patients. Recognition of this overlap is essential for appropriate therapeutic decision-making, including potential escalation to biologic agents targeting T-cell cytokine pathways.