Clinical Significance of Malassezia-Specific IgE in Assessing the Severity of Head and Neck Involvement in Korean Atopic Dermatitis Patients.

Head and neck dermatitis (HND) is a distinct clinical phenotype of atopic dermatitis (AD). While Malassezia sensitisation and elevated Malassezia-specific IgE antibody (MSIA) levels have been documented in HND patients, the relationship between MSIA levels and disease severity remains controversial. The primary aim of our study was to evaluate whether MSIA levels correlate with the severity of HND. This retrospective observational study was conducted at a single tertiary center and included 121 patients with AD. Laboratory data included serum MSIA, house dust mite (HDM)-specific IgE and total IgE levels. Clinical severity was measured using the global Eczema Area and Severity Index (EASI) and partial HND EASI scores. We introduced a novel metric, the 'relative HND severity score', defined as the HND EASI score divided by the global EASI score. Spearman's Rho correlation analyses were used to examine the correlations between different IgE levels and severity scores. The HND EASI score demonstrated significant positive correlations with MSIA (r = 0.569, p < 0.001) and both HDM-specific antibodies: D1 (r = 0.247, p = 0.007) and D2 (r = 0.267, p = 0.004). The relative HND severity score was significantly positively correlated with MSIA (r = 0.353, p < 0.001), but not with HDM-specific antibodies (D1, p = 0.985; D2, p = 0.974). Age-stratified subgroup analyses revealed significant positive correlations between MSIA and both absolute (r = 0.591, p < 0.001) and relative HND severity (r = 0.344, p = 0.002) only in the adult cohort. In conclusion, serum MSIA levels significantly correlate with the clinical severity of HND in Korean AD patients. This association is most clearly observed in the adult population.