Dupilumab-Induced Generalized Lichen Planus: A Case Report

Lichen planus (LP) is a chronic inflammatory skin disease of unknown cause. Common subtypes include generalized LP, linear LP, annular LP, and hypertrophic LP. Current clinical evidence suggests that lichen planus is a T-cell-mediated autoimmune disorder. Therefore, an increasing number of clinicians are opting for biologics or immunomodulators to manage lichen planus, but the reported evidence on their efficacy and safety remains limited.

This case report describes a 32-year-old female with pre-existing localized lichen planus (LP) who developed generalized LP after IL-4Rα inhibitor dupilumab therapy. Following three dupilumab injections, progressive dissemination of pruritic pink-to-flesh-coloured or light-brown papules to the trunk and limbs was observed. The lesions regressed upon dupilumab discontinuation and pharmacological intervention. Diagnosis was confirmed by dermoscopy and histopathology.

A temporal correlation and Naranjo adverse drug reaction score of 8 indicated dupilumab as the trigger, likely via Th1/Th2 immune deviation. This first-documented paradoxical reaction underscores dupilumab's potential to trigger generalized LP through immune deviation.