Abstract
Chronic actinic dermatitis (CAD) is an immune-mediated photodermatosis characterised by eczematous, pruritic changes to sun-exposed skin. The pathophysiology of CAD is poorly understood, with current explanations including a hypersensitivity reaction and cross-reactivity to contact allergens. The disease is often refractory to immunosuppressive treatment and has a marked impact on patient quality of life. Janus kinase inhibitors (JAKi) are a novel class of small molecules licenced for the management of certain inflammatory conditions, including atopic dermatitis We present the case of a 69-year-old gentleman with a history of severe CAD, unresponsive to standard therapies, who was prescribed baricitinib, a janus kinase (JAK) inhibitor as a single agent treatment for his disease. The patient experienced a dramatic clinical improvement with this therapy. In addition, normalisation of photo test and improvement of patch test results following treatment were observed. There is one previous case report in the literature describing the clinical response of patients with CAD to JAK inhibitor therapy, but no comment on pre or post treatment photo testing, patch testing or photo-patch testing results was made. In this case report, we discuss our understanding of the role of JAK inhibitors in CAD and highlight a potential new therapeutic avenue for this disabling disease.