Early-Onset Severe Atopic Dermatitis With Hyper-IgE Overlap in a Child With a Heterozygous FLG Variant: A Case Report

Markedly elevated IgE in children is an important but nonspecific clue, particularly with early-onset atopic dermatitis, eosinophilia, and infections. We report a boy who developed generalized eczema at approximately 6 months of age and was repeatedly hospitalized during infancy for severe dermatitis, prolonged diarrhea, pneumonia, acute otitis media, and Staphylococcus aureus bacteremia. Early investigations showed eosinophilia, hypoalbuminemia, rapid IgE escalation, and lymphocyte subsets not suggestive of a clear T-, B-, or NK-cell deficiency. After 12 months, no further severe infections requiring hospitalization were documented, whereas chronic severe dermatitis, eosinophilia, markedly elevated IgE, and later asthma became dominant. Whole-exome sequencing identified two FLG variants; among these, Sanger sequencing confirmed a heterozygous FLG NM_002016.2:c.6950_6957del (p.Ser2317Ter) variant. This case highlights overlaps between severe barrier-related atopic dermatitis and hyper-IgE syndrome and emphasizes longitudinal follow-up, immunological evaluation, vaccine history, genetic interpretation, and gene-environment interactions.