Clinical and Immunological Phenotypes of Alopecia Areata in Children with Concomitant Atopic Dermatitis: Results of a Cluster Analysis

Background. Alopecia areata (AA) and atopic dermatitis (AD) are chronic immune-mediated diseases that frequently coexist in children. Despite established epidemiological links, the internal structure of this comorbidity, including how objective disease severity and polyatopy correlate, remains poorly characterized. Aim. To identify and characterize clinical-immunological phenotypes of AA in children with concomitant AD using cluster analysis. Methods. A single-center, cross-sectional study included 68 children aged 5—16 years with AA and AD. Assessments included disease severity (SALT, SCORAD), age of AA onset, serum total IgE, quality of life (CDLQI), and atopic comorbidity (Atopy Index: 0=AD only, 1=+1 atopic condition, 2=+≥2 conditions). Spearman’s correlation and k-means clustering (variables: SALT, SCORAD, IgE, age of AA onset) were used. Results. Correlation analysis revealed a moderate positive association between AA and AD severity (ρ=+0.512, p<0.001). Earlier AA onset correlated significantly with more severe hair loss (ρ=–0.418, p=0.001). Cluster analysis identified three distinct phenotypes: (1) «Early-Onset, Severe AA» (n=22): Early onset (3.0 years), universal hair loss (SALT 100.0%), high CDLQI (11.0); (2) «Late-Onset, Mild Disease» (n=25): Later onset (8.0 years), mild AA (SALT 18.8%) and AD (SCORAD 22.6), lowest IgE (87.6 IU/mL); (3) «Severe Atopic» (n=21): Extreme atopy with highest IgE (847.0 IU/mL), severe AD (SCORAD 52.7) and AA (SALT 77.5%). A higher Atopy Index was associated with increased AD severity (p=0.003) and IgE levels (p=0.015). Conclusion. This study reveals significant heterogeneity in pediatric AA with AD, delineating distinct phenotypic profiles. The findings suggest at least two pathways to severe alopecia: one driven by very early disease onset and another by a severe, systemic Th2 atopic burden. Stratification by age of onset, disease severity, and atopic load facilitates personalized management and identifies children at the highest risk for severe disease and quality of life impairment.