Atopic dermatitis without serum immunoglobulin E elevation or loss‐of‐function filaggrin gene mutation in a patient with X‐linked agammaglobulinemia.

A case of atopic dermatitis (AD) with X‐linked agammaglobulinemia (XLA), which is one of the primary immunodeficiency diseases, is reported. A 12‐year‐old boy had suffered from dry skin and recurrent itchy eruptions since he was 2 years old, and he was diagnosed as having XLA at the age of 4 years. His total immunoglobulin (Ig)E level was 7 IU/mL, even with regular Ig replacement therapy. Furthermore, filaggrin (FLG) mutations known in the Japanese population were not found. His skin lesions were well controlled by the application of a mild‐class topical steroid and a moisturizer, though he developed folliculitis due to Staphylococcus aureus infection during treatment with a strong‐class topical steroid. This case suggests that the FLG mutation and IgE‐mediated sensitization are not necessary to induce AD skin manifestation. [ABSTRACT FROM AUTHOR]