STAT3-Mutated Hyper-IgE Syndrome With Retroperitoneal Abscess in Adolescence.

Hyperimmunoglobulin E syndrome (HIES) is a rare primary immunodeficiency disorder characterized by eczema, recurrent staphylococcal infections, and significantly elevated serum IgE levels. An 18-year-old female presented with acute abdominal pain and was diagnosed with a retroperitoneal abscess. She had a history of recurrent skin abscesses, otitis media, and eczema since infancy, skeletal fractures, and retained primary teeth. Laboratory findings showed a serum IgE level above 20,150 U/L and a CRP of 180.30 mg/L. Methicillin-sensitive Staphylococcus aureus was cultured from the abscess drainage. The NIH-HIES score was 60 points. Genetic testing identified a heterozygous STAT3 variant (NM_139276.3: c.1145G>A, p.(Arg382Gln)), confirming autosomal-dominant HIES. This rare clinical presentation emphasizes the importance of considering HIES, even when deep-seated infections develop outside typical cutaneous or pulmonary sites.