Severe Dupilumab-Associated Psoriasis Flare After Switching From Ustekinumab for Biopsy-Proven Eczematous Dermatitis: A Case Report.

Dupilumab is an effective treatment for moderate-to-severe atopic dermatitis but has been increasingly associated with paradoxical psoriasis and psoriasiform manifestations. Severe exacerbation of pre-existing psoriasis following dupilumab therapy remains uncommon and presents a therapeutic challenge. We report a patient with well-controlled chronic plaque psoriasis who developed eczematous dermatitis with histopathological findings consistent with the diagnosis. Although dupilumab effectively controlled the eczema, the patient subsequently developed a severe generalized psoriasis flare after switching from ustekinumab. Clinical improvement was achieved after restarting ustekinumab and methotrexate. This case highlights the potential for dupilumab to trigger severe paradoxical psoriasis in patients with pre-existing psoriatic disease. Clinicians should remain vigilant when prescribing dupilumab in this population, and early recognition with prompt modification of therapy may lead to favorable clinical outcomes.