Atypical Localization of Eczema Discriminates DOCK8 or STAT3 Deficiencies from Atopic Dermatitis

Autosomal recessive dedicator of cytokinesis 8 (DOCK8^-/-) and autosomal dominant signal transducer and activator of transcription 3 (STAT3^-/+) deficiencies are inborn errors of immunity (IEI) disorders present with the classic features of eczema and create a dilemma during differentiation from atopic dermatitis (AD). Therefore, an appropriate approach is required for eczema to diagnose DOCK8^-/- and STAT3^-/+ early. Here, we described a set of clinical and immunological variables, including atypical AD localizations and lymphocyte subsets, to differentiate DOCK8^-/- or STAT3^-/+ from AD.

This multicenter study involved 100 patients with DOCK8^-/- and STAT3^-/+ and moderate/severe AD. We recruited disease manifestations, including detailed localizations of eczema, infections, and allergy. Principle component analysis (PCA) was used to discriminate DOCK8^-/- or STAT3^-/+ from AD.

There were 43 patients with DOCK8^-/-, 23 with STAT3^-/+, and 34 with AD. Pneumonia, severe infections, mucocutaneous candidiasis, and skin abscesses were commonly observed in DOCK8 and STAT3 deficiencies. Atypical skin involvement with neonatal rash, retro auricular, axillary, sacral, and genital eczema discriminate DOCK8^-/- and STAT3^-/+ from AD with high specificity ranges between 73.5 and 94.1% and positive predictive index ranges between 55 and 93.1%. Together with using absolute numbers of CD3⁺, CD4⁺, and CD8⁺ T cells, the combined clinical and laboratory features showed perfect differentiation between DOCK8^-/- or STAT3^-/+ and AD via PCA.

The described features can be easily implemented by physicians providing early diagnosis of DOCK8 and STAT3 deficiencies.