A Case of Lichenoid Drug Eruption Following Risankizumab Therapy

Psoriasis (PsO) is a chronic inflammatory disorder that significantly impairs quality of life and is associated with numerous comorbidities. Risankizumab, a biologic therapy targeting the p19 subunit of interleukin (IL)-23, has emerged as a potent treatment option due to its ability to disrupt the IL-23/IL-17 inflammatory cascade responsible for psoriatic pathogenesis. Despite its demonstrated efficacy and safety, risankizumab’s potential for rare adverse reactions necessitates vigilant post-marketing surveillance. This case reports the first documented instance of a lichenoid drug eruption in a 79-year-old female with psoriasis following treatment with risankizumab. The reaction manifested as erythematous patches across her chest, face, neck, and calf, which improved upon cessation of risankizumab and resumption of methotrexate supplemented by narrow-band UVB therapy. This case highlights the need for ongoing surveillance of adverse side effects associated with newer biologic therapies to enhance patient management and safety.