Secukinumab‐induced oral lichen planus in a psoriatic arthritis patient ameliorated after a switch to risankizumab

Abstract Lichen planus is a chronic T‐cell‐mediated disorder in which lymphocytes, including Th17 cells, react toward the dermo‐epidermal junction, which shows interface changes. Recently, IL‐17‐mediated changes in the oral mycobiome, including the proliferation of Candida and Aspergillus fungi, have been proposed as a possible pathomechanism of oral lichen planus (OLP). We treated a 54‐year‐old male who had been suffering from psoriatic arthritis. Secukinumab rapidly improved the skin and joint symptoms, but a painful erosion on the lip and thrush on the buccal mucosa appeared within 4 weeks. The erosion was histopathologically diagnosed as OLP. Although the candidiasis was successfully treated with topical miconazole nitrate, the labial OLP worsened during the secukinumab administration, despite the application of various topical agents. We finally switched from secukinumab to risankizumab, an anti‐IL‐23p19 agent, which dramatically improved the patient's OLP lesion in 4 weeks without candidiasis recurrence. Anti‐IL‐23p19 agents do not affect the oral mycobiome, and they are a potential therapeutic option for refractory OLP, including OLP induced by biologics.