Psoriasis and Bullous Pemphigoid: An Updated Review of Clinical Association, Targeted Therapy Exposures and Therapeutic Implications

Psoriasis is a chronic immune-mediated inflammatory dermatosis driven predominantly by dysregulation of the interleukin-23–T helper 17 axis. Bullous pemphigoid is a distinct autoimmune subepidermal blistering disorder characterized by autoantibody-mediated injury at the dermal–epidermal junction and a T helper 2-polarized, eosinophil-rich inflammatory response. Despite their marked clinical and immunopathological differences, accumulating epidemiological evidence suggests that the coexistence of psoriasis and bullous pemphigoid is unlikely to be incidental. Therapeutic exposure may also contribute to this association. Biologic agents used to treat psoriasis, and in selected cases bullous pemphigoid, have occasionally been reported in temporal association with new-onset bullous pemphigoid. These observations raise the hypothesis that divergent treatment-related effects may partly reflect differences in the prevailing immune milieu rather than a uniform property of a specific drug class. This review summarizes current evidence on the clinical association between psoriasis and bullous pemphigoid, critically examines targeted therapy exposures and their divergent clinical contexts, and discusses the immunopathogenic mechanisms that may contribute to the development of bullous pemphigoid in patients with psoriasis. Particular attention is given to the implications of these findings for individualized clinical management.