Emergence of Vitiligo during Treatment with Risankizumab-Rzaa for Plaque Psoriasis: A Case Report.

Introduction: Risankizumab-rzaa (Skyrizi) is a humanized monoclonal antibody (IgG1) approved for the treatment of severe plaque psoriasis. It selectively blocks the p19 subunit of the IL-23 pathway, leading to reduced keratinocyte proliferation reducing the inflammatory response. Case Presentation: We present a case of de novo vitiligo in a patient being treated with risankizumab-rzaa (Skyrizi) for plaque psoriasis. Our patient had extensive plaque psoriasis affecting his trunk, upper extremities, and scalp, encompassing 30% of his total body surface area. He was treated with risankizumab-rzaa, an IL-23 inhibitor, with significant improvement of his psoriasis and residual hyperpigmented, post-inflammatory patches. In addition, he developed new-onset vitiligo, for which he declined treatment and was continued on risankizumab-rzaa. On subsequent follow-up over a year later, there were extensive areas of vitiligo now with a trichrome pattern suggestive of active vitiligo. Conclusion: To our knowledge, no cases of de novo vitiligo associated with risankizumab-rzaa have been reported in the literature, and our patient may represent the first reported case. The role of IL-23 remains unclear, and our case represents the importance of further research to better elucidate IL-23's role in vitiligo.