Managing the Overlap: Therapeutic Approaches in Patients with Concomitant Psoriasis and Atopic Dermatitis-A Case Series.

Introduction: Psoriasis (PSO) and atopic dermatitis (AD) have traditionally been considered distinct diseases, respectively, mediated by T-helper 1 (Th1) and the T-helper 2 (Th2) immune pathway. In recent years, there has been a growing body of evidence highlighting an overlap between the two conditions, such as Asian AD, pediatric PSO, or "psoriasis dermatitis/PSOREMA". Moreover, psoriasis dermatitis can be induced by therapeutic interventions. For instance, anti-IL-4/IL-13 monoclonal antibodies, commonly used to treat AD, can induce psoriasiform reactions by inhibiting the Th2 pathway, thereby unmasking Th1/Th17-driven PSO. Conversely, anti-TNFα and anti-IL-17 therapies, effective for PSO, may induce eczematous reactions promoting a switch toward Th2-driven inflammation. Janus Kinase Inhibitors (JAK-i) and IL-23 antagonists may represent valid therapeutic options for managing psoriasis dermatitis. JAK-i exert broader immunomodulatory effects, inhibiting both Th1 and Th2 pathways; however, they require careful monitoring due to potential adverse events. In contrast, IL-23 antagonists specifically suppress the IL-23/IL-17 axis inhibiting the p19 subunit of IL-23 and could represent a safer option for patients with psoriasis dermatitis. Materials and Methods/Results: We present a series of five cases of psoriasis dermatitis, including both patients who had the condition from the onset and those who developed it during treatment, with tailored therapeutic strategies based on individual patient profiles, comorbidities, and the specific characteristics of their overlapping disease presentation. Conclusion: JAK-i and IL-23 antagonists are both valid therapeutic options for managing psoriasis dermatitis, but with different immunomodulatory effects and safety profiles. Future research should focus on a better understanding of the immune pathway and identifying specific biomarkers of psoriasis dermatitis, to optimize therapeutic strategies.