Psoriasis-Atopic Dermatitis Phenotype Switching: New Real-World Data

Treatment-associated phenotype switching between psoriasis and atopic dermatitis is a clinically relevant, reproducible, and bidirectional real-world phenomenon, new data suggest, and may need to be recognized in clinical settings to guide therapeutic adaptation in certain cases.1

These findings resulted from a retrospective, multi-center, multinational observational study designed to evaluate treatment-associated phenotype switching in inflammatory skin conditions across 17 dermatology centers located across Spain, Portugal, Italy, Switzerland, Greece, and Canada. The team was led by Tiago Torres, MD, PhD, professor of dermatology at the Instituto de Ciências Biomédicas Abel Salazar, University of Porto.

Torres et al reviewed real-world clinical findings to characterize cases in which individuals who are being treated for atopic dermatitis or for psoriasis developed a persistent change in clinical morphology at the time they received systemic or biologic medication.

“While isolated case reports and small case series have described this entity, systematic real-world data on clinical characteristics, triggering therapies and management strategies remain limited,” Torres and coauthors wrote.1,2

Study Design Details

Torres et al noted their definition of a phenotype switch in clinical practice as one’s dermatologist noting the sustained emergence of features consistent with the opposite disease. For example, psoriasiform findings in individuals with atopic dermatitis, or eczematous shifts in those on a treatment for psoriasis. It would specifically be when such changes took place temporally in connection with systemic or biologic exposure and were significant enough to prompt a management shift.

A histopathology or molecular testing-confirmation was not required, the investigative team noted, reflecting routine clinical decision-making in real-world clinical settings. Those deemed eligible included subjects showing established psoriasis or atopic dermatitis diagnoses who had also subsequently developed a clinician-documented, persistent phenotype change deemed related to systemic or biologic therapy and leading to changes in therapeutic agents.

Torres and colleagues gathered various demographic data, characteristics related to disease, treatment histories, and outcomes across participating centers. Their analyses were mainly descriptive in nature, with continuous variables summarized via assessment of central tendency and dispersion. Additionally, the team reported categorical variables as frequencies and proportions.

Where they deemed comparisons appropriate, the investigators implemented chi-square or Fisher’s exact tests for categorical data. Student’s t-test or Mann–Whitney U testing was used for continuous variables, depending on distribution.

Findings on Treatment-Associated Phenotype Switching

148 subjects met the investigators’ inclusion criteria. Among these, 68.2% with psoriasis developed eczematous features over the course of their therapy (psoriasis-to-eczema phenotype switch). Meanwhile, Torres and coauthors found 31.8% of these 148 patients, those with atopic dermatitis specifically, developed psoriasiform manifestations while on treatment (atopic dermatitis-to-psoriasis switch).

Unique clinical patterns emerged between the patient cohorts. Those showing psoriasis-to-eczema transitions tended to be older and had an increased burden of cardiometabolic comorbidities. Atopic comorbid conditions, by contrasting, were more often noted among those in the atopic dermatitis-to-psoriasis patient cohort.

Torres et al further noted therapeutic exposure appeared to differ by direction of switch. Most of the cases of psoriasis-to-eczema took place in patients on interleukin (IL)-17 or IL-23 pathway inhibitors. Alternatively, atopic dermatitis-to-psoriasis switches were seen exclusively among those treated with biologics targeting type 2 inflammation. Most commonly, this was seen with dupilumab.

In all cases, treatment was shifted after the phenotype change emerged. Janus kinase (JAK) inhibitors were shown to be the most frequently selected therapeutic strategy across both directions of switching. Particularly high utilization in the psoriasis-to-eczema cohort was observed. Across the study population, modification of therapeutic agents were generally linked with substantial clinical improvement, regardless of phenotype direction.

Overall, Torres and colleagues’ results support treatment-associated phenotype switching between psoriasis and atopic dermatitis as a bidirectional and as a reproducible phenomenon seen in routine clinical practice settings. They suggest, instead of representing paradoxical disease induction, the pattern likely indicates underlying immune system plasticity impacted by targeted pathway inhibition.

“Prospective studies integrating longitudinal clinical assessment with histological and molecular profiling will be essential to identify predictors of phenotype switching and to inform precision therapeutic approaches,” they concluded.1

References

1. Torres T, Valenti M, Prajapati V, et al. Treatment-associated phenotype switching between psoriasis and atopic dermatitis. J Eur Acad Dermatol Venereol. 2026; 00: 1–9. https://doi.org/10.1111/jdv.70503.

2. Al-Janabi A, Foulkes AC, Warren RB, et al. Phenotypic switch to eczema in patients receiving biologics for plaque psoriasis: a systematic review. J Eur Acad Dermatol Venereol. 2020 Jul;34(7):1440-1448. doi: 10.1111/jdv.16246. Epub 2020 Feb 27. PMID: 31997406.