000855 - A Comprehensive Multicenter Evaluation of Pediatric Angioedema: Clinical Manifestations, Atopic Comorbidities, and Laboratory Profiles

Angioedema is characterized by localized, transient swelling of the subcutaneous or submucosal tissues, occurring either in isolation or in association with urticaria. Despite its clinical significance, comprehensive reports on the clinical spectrum of angioedema in the pediatric population remain limited. This study aimed to describe the clinical manifestations, identify common atopic comorbidities, and evaluate the laboratory profiles of pediatric patients presenting with angioedema.

We collected clinical histories and performed laboratory evaluations for children with a history of angioedema who visited the Departments of Pediatrics at four tertiary hospitals between January and December 2025. Demographic data, the number of angioedema episodes, and detailed clinical features of the most recent episode were recorded. Laboratory evaluations included complement 3 (C3) and C4, C1 inhibitor (C1-INH) levels, C1-INH functional assays, and assessment of allergic sensitization.

A total of 29 pediatric patients with angioedema were analyzed (median age at recent episode 10.7 years [range 1.9–19.1], 37.9% male). Allergic rhinitis (58.6%) and atopic dermatitis (34.5%) were the most common comorbidities, and 24.1% of patients had a family history of angioedema symptoms. Recurrent episodes occurred in 72.4% of patients, with an estimated mean frequency of 10.4 episodes (median 5, range 2–50). In the most recent episode, the most frequently affected sites were the eyes (51.7%), face (37.9%), and lips (31.0%), followed by the hands (13.8%). Laryngeal involvement, including symptoms of dyspnea, hoarseness, or dysphagia, was reported in 10.3% of cases. Prodromal symptoms, such as headache or abdominal discomfort, were observed in 17.2%, and wheals were accompanied in 41.4% of patients. Regarding the duration of swelling, 25.9% of cases resolved within 2 hours, 27.6% within 2–12 hours, 10.3% within 12–24 hours, 7.4% within 24–48 hours, and 25.9% persisted for more than 48 hours. Acute treatment was administered in the majority of cases, with antihistamines being the most frequently used (82.8%), followed by systemic corticosteroids (48.3%) and epinephrine (6.9%). Laboratory evaluations showed median C3 and C4 levels of 108 mg/dL (range 85–143) and 18 mg/dL (range 10–35), respectively. The median C1-INH level was 32.1 mg/dL (range 24.5–50.6), and the median C1-INH function was 97% (range 65.9–137.5), all of which were within normal reference ranges. Antinuclear antibody was positive in 20.7% of patients, and the median total IgE level was 362.3 kU/L (range 6–1248). The specific sensitization rates were 37.9% for house dust mites, 27.6% each for tree and weed pollens, 20.7% for grass pollens, 13.8% each for cat and dog dander, and 10.3% for molds.

This study indicates that pediatric angioedema primarily affects the eyes, face, and lips, with a high prevalence of recurrent episodes. Normal complement and C1-INH results suggest that acquired or idiopathic forms predominate in this cohort. [Acknowledgment: This research was supported and funded by SNUH Lee Kun-hee Child Cancer & Rare Disease Project, Republic of Korea (grant number : 25A-000-0000).]