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, which was unresponsive to multiple systemic treatments, including immunosuppressants, dupilumab and tofacitinib. All patients presented with marked photosensitivity and two had erythroderma. Extensive investigation excluded cutaneous T-cell lymphoma. Photobiological testing demonstrated reduced minimal erythema doses to ultraviolet B 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 patient. These findings suggest that selective Janus kinase 1 inhibition may represent a therapeutic option in severe treatment-refractory CAD.