PA31 The role of the dermatologist in identifying inborn errors of immunity in patients presenting with atopic dermatitis

Abstract This case aims to highlight the role dermatologists have in identifying inborn errors of immunity, particularly in patients who do not respond to eczema treatments and those with concurrent food allergies and severe recurrent infections. A 1-year-old boy with severe allergies to eggs, nuts, milk and sesame, with a history of anaphylaxis, presented to dermatology for the management of generalized severe atopic dermatitis with prominent facial and scalp involvement. Despite prompt treatment with topical corticosteroids and topical calcineurin inhibitors there was no improvement in the skin. Additionally, he had repeated severe infections including impetiginized eczema, eczema herpeticum, eczema molluscatum, respiratory tract infections, and chronic otitis media leading to hearing loss. His height was on the 9th centile and weight on the 25th centile. Initial bloods suggested anaemia: haemoglobin 98 g L−1 with leucocytosis (17.7 × 109 cells L−1), neutrophilia (9.6 × 109 cells L−1) and lymphopenia (4.7 × 109 cells L−1). He also had a high IgE level of 27 804 IU mL−1. This raised the suspicion of an inborn error of immunity, and he subsequently underwent genetic studies. Gene sequencing studies revealed a DOCK8 deletion of exons 6–14 and c.2660C>G, p.(Ser887*) compound heterozygosity. Deficiency of the dedicator of cytokinesis 8 gene (DOCK8) is a combined type of T- and B-cell immunodeficiency, previously known as autosomal recessive hyper-IgE syndrome. The patient was started on immunoglobulin infusions and dupilumab, with some improvement in his eczematous rash, before receiving a 100% matched unrelated-donor haematopoietic stem cell transplantation (HSCT). Early recognition of this condition and definitive treatment with HSCT is important due to the associated high morbidity and mortality of DOCK8 deficiency. Clinically, patients present with severe eczema, multiple food allergies, environmental allergies and asthma, and are at an increased risk of developing severe and difficult-to-treat viral, bacterial and fungal infections. Cutaneous viral infections, including varicella zoster, molluscum contagiosum, herpes simplex and human papillomaviruses tend to be common. Certain localizations of eczema in the retroauricular, axillary, groin and back areas have been described in the literature. Morphology ranges from distinctive papulopustular, vesicular rashes to abscesses. Infected dermatitis due to Staphylococcus aureus or viral infections is thought to be related to DOCK8 mutations. However, the molecular link between DOCK8 deficiency and atopic skin inflammation remains unknown. This case highlights the importance of considering inborn errors of immunity in such cases of severe eczema associated with apparent immune dysregulation and susceptibility to recurrent infections.