Paradoxical Rashes from Biologics

This lecture addresses paradoxical rashes associated with biologic treatments, specifically focusing on those induced by TNF inhibitors, such as paradoxical psoriasis. Paradoxical rashes are unique immune-mediated inflammatory reactions that can occur when patients receive biologics typically used to treat those very conditions. Most cases involve TNF inhibitors, which, despite being known to treat psoriasis, may cause worsening or new patches of psoriasis in some patients, usually showing up around 1.5 years post-treatment. The phenomenon raises skepticism as pre-existing conditions may be misattributed to biologics, and there are significant limitations in the existing studies supporting the causality. Nevertheless, the distinct clinical presentation and biopsy findings of paradoxical psoriasis, including different histological characteristics, offer support for its classification. Management poses challenges, often requiring discontinuation of the TNF inhibitor for severe rashes, although milder cases might be treated through continued use of the biologic alongside other therapies. The speaker discusses novel rash variants, including eczematized psoriasis and pustular folliculitis, and emphasizes the need for personalized treatment strategies. Other biologics and JAK inhibitors are considered viable alternatives in managing paradoxical rashes. Finally, the discussion touches on the mechanisms behind these reactions, specifically the complex interactions of the immune system and various cytokines in skin pathology.