Fungal Head and Neck Dermatitis: Current Understanding and Management.

Head and neck dermatitis (HND) is a form of atopic dermatitis (AD) that affects the seborrheic areas of the body and causes greater quality of life detriments than other types of AD. HND can be challenging to treat since first-line topical therapies may be ineffective or intolerable for long-term use on areas affected by HND while dupilumab may cause dupilumab-associated HND (DAHND). Current evidence implicates fungi, particularly Malassezia spp., in the pathogenesis of HND. Penetration of fungal antigens through the defective AD skin barrier activates the innate and adaptive immune systems to cause cutaneous inflammation via the T helper (Th)17 and/or Th2 axes. Malassezia sensitization may distinguish HND from other forms of AD. Multiple double-blind, placebo-controlled trials have shown antifungals to benefit HND, yet the persistence of symptom relief with sustained use remains unclear. Oral antifungals appear more effective than topical antifungals but may be harmful with long-term use. DAHND may also be fungal-mediated given improvement with antifungals and evidence of an overactive immune response against Malassezia in these patients. Janus kinase inhibitors are effective for HND, including DAHND, but may cause significant side effects when administered systemically. OX40/OX40L inhibitors and tralokinumab may be promising options for HND on the horizon. Demographic and environmental factors influence the host mycobiome and should be considered in future precision-medicine approaches as microbiome composition and diversity are linked to severity of HND.