Successful Treatment of Severe Refractory Chronic Actinic Dermatitis with Upadacitinib: A Case Series of Four Patients

Chronic actinic dermatitis (CAD) is a rare, immune-mediated photodermatosis that may be severe, generalized, and refractory to conventional therapies. We describe four men (aged 44-65 years) with long-standing, severe CAD unresponsive to multiple systemic treatments, including immunosuppressants, dupilumab, and tofacitinib. All patients presented with marked photosensitivity; two had erythroderma. Extensive investigation excluded cutaneous T-cell lymphoma. Photobiologic testing demonstrated reduced minimal erythema doses to UVB adjusted for phototype, supporting the diagnosis of CAD. Upadacitinib (15-30 mg once daily) was initiated off-label. Clinical improvement occurred within 4 weeks, with complete remission achieved between 4 and 8 weeks in all patients. Remission was sustained for up to 12 months of follow-up. Treatment was well tolerated, with only mild acneiform eruption and transient hypertriglyceridaemia in one case. These findings suggest that selective JAK1 inhibition may represent a therapeutic option in severe, treatment-refractory CAD.