Insights into the microcirculation in pediatric chronic spontaneous urticaria: A nailfold videocapillaroscopy study

Background Chronic spontaneous urticaria (CSU) is increasingly recognized as a systemic inflammatory disease with endothelial involvement extending beyond the skin. Nailfold videocapillaroscopy (NVC) has demonstrated systemic microvascular abnormalities in adults with CSU, but pediatric data are lacking. We investigated nailfold microvascular alterations in children with CSU and their associations with disease activity, disease control, autoreactivity, and inflammatory markers. Methods In this cross‐sectional study, 41 children with CSU underwent standardized NVC according to EULAR recommendations. Qualitative and quantitative capillaroscopic findings were compared with age‐specific normative values. Associations with Urticaria Activity Score over 7 days (UAS7), Urticaria Control Test (UCT), antinuclear antibodies (ANA), autologous serum skin test (ASST), anti‐thyroid peroxidase (anti‐TPO) antibodies, and laboratory parameters were assessed. Results Children with CSU exhibited reduced capillary density (7.1 ± 1.3 vs. 8.1 ± 1.7), arterial diameter (9.4 ± 2.9 vs. 11.9 ± 4.0 μm), venous diameter (9.5 ± 2.8 vs. 15.1 ± 4.6 μm), apical loop diameter (12.4 ± 3.2 vs. 16.3 ± 5.5 μm), and capillary width (36.1 ± 6.7 vs. 41.5 ± 9.0 μm) (all p < .001), whereas capillary length and intercapillary distance were preserved ( p = .948 and p = .395). Capillary density correlated positively with disease duration ( r = 0.338, p = .031) and UAS7 ( r = 0.328, p = .037), and negatively with UCT ( r = −0.428, p = .005). Capillaroscopic findings were largely independent of ANA, ASST, and anti‐TPO status, supporting a reactive, non‐destructive microvascular process. Conclusions This study provides the first in vivo evidence of systemic microvascular involvement in pediatric CSU. The capillaroscopic profile supports recurrent endothelial activation rather than destructive microangiopathy and highlights NVC as a simple, non‐invasive tool for evaluating systemic vascular involvement in children with CSU.