Treatment‐associated phenotype switching between psoriasis and atopic dermatitis

Year: 2026

Type: article

Abstract: Psoriasis and atopic dermatitis (AD) are traditionally viewed as distinct inflammatory skin diseases driven by type 17 and type 2 immune pathways, respectively. Increasing use of targeted therapies has revealed a treatment-associated phenotype switch between these conditions, the so-called 'flip-flop' phenomenon, characterized by sustained emergence of eczematous features in patients treated for psoriasis or psoriasiform disease in those treated for AD. Robust real-world data on this entity remain limited. OBJECTIVES: To characterize treatment-associated phenotype switching between psoriasis and AD in a large real-world cohort, focusing on clinical features, implicated therapies, management strategies and outcomes. METHODS: We conducted a retrospective, multicentre, multinational observational study across 17 dermatology centres in six countries. Patients with psoriasis or AD who developed a clinician-defined, persistent phenotype switch temporally associated with systemic or biologic therapy and requiring treatment modification were included. Demographic, clinical, therapeutic and outcome data were collected and analysed descriptively. RESULTS: A total of 148 patients were included: 101 (68.2%) developed eczematous features while treated for psoriasis (PsO → eczematous), and 47 (31.8%) developed psoriasiform disease while treated for AD (AD → psoriasiform). PsO → eczematous patients were older and had more cardiometabolic comorbidities, whereas atopic comorbidities were more frequent in the AD → psoriasiform group. PsO → eczematous switches occurred mainly under interleukin (IL)-17 and IL-23 inhibitors, while AD → psoriasiform switches occurred exclusively during biologic therapies targeting type 2 inflammation, predominantly dupilumab. Treatment was modified in all patients. Janus kinase (JAK) inhibitors were the most frequently used strategy in both switch directions, particularly in PsO → eczematous cases. Marked clinical improvement was observed across phenotypes following therapeutic adjustment. CONCLUSIONS: Treatment-associated phenotype switching between psoriasis and AD is a reproducible, bidirectional and clinically relevant real-world phenomenon reflecting immune plasticity rather than paradoxical disease induction. Recognition of this entity is essential to guide appropriate therapeutic adaptation, with JAK inhibitors emerging as a commonly effective management option.

Source: Journal of the European Academy of Dermatology and Venereology

DOI: 10.1111/jdv.70503

Institutions: Universidade do Porto, Instituto de Ciências Biomédicas Albel Salazar, Humanitas University, IRCCS Humanitas Research Hospital, University of Campania "Luigi Vanvitelli", Federico II University Hospital, University of Naples Federico II, University of Verona, University of Calgary, Probity Medical Research, University of Padua, University of Zurich, University Hospital Zurich, Universitat Autònoma de Barcelona, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Hospital Universitari Germans Trias i Pujol, Instituto de Investigación Biosanitaria de Granada, Aristotle University of Thessaloniki, University of Toronto, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Florence, Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria del Hospital Universitario de La Princesa, Dermatrials Research, McMaster University, Women's College Hospital, Hospital de Sant Pau

Language: English

Topic: Psoriasis: Treatment and Pathogenesis

Subfield: Immunology

Field: Immunology and Microbiology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $5,450

Funders: Universidade do Porto, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto

OpenAlex ID: W7161163515