Supplementary Material for: Dupilumab's Successful Journey in Pityriasis Lichenoides Chronica Followed by the Intriguing Reemergence of Vitiligo After Monobenzone Depigmentation: A Case Report

Abstract
Background
Pityriasis lichenoides (PL), comprising acute (PLEVA) and chronic (PLC) subtypes, represents a spectrum of inflammatory skin conditions with overlapping clinical and histopathological features. Standard treatments include oral antibiotics, phototherapy, and immunosuppressive agents. Dupilumab, an IL-4Rα antagonist, is approved for atopic dermatitis and used off-label for other inflammatory skin conditions but has limited documentation in PL treatment.
Objective
To report a novel case of successful PLC management with dupilumab and an unexpected reemergence of skin pigmentation following prior monobenzone depigmentation therapy for vitiligo.
Methods
A 40-year-old female with a history of extensive vitiligo and monobenzone depigmentation therapy presented with scaly, erythematous plaques and severe pruritus. Skin biopsy confirmed PLC. Conventional treatments were declined due to concerns about pigmentation changes. Dupilumab was initiated at a loading dose of 600 mg, followed by 300 mg biweekly.
Results
After three months of dupilumab therapy, significant improvement in PLC lesions and pruritus was observed, with only residual erythematous plaques. Remarkably, skin repigmentation occurred spontaneously, contrasting with previously reported cases of vitiligo exacerbation following dupilumab use. Depigmentation therapy with monobenzone was resumed without exacerbating PLC or pruritus.
Conclusion:
This case highlights dupilumab's potential as an effective treatment for PLC and its intriguing role in promoting skin repigmentation in a patient with prior vitiligo. These findings suggest a possible link between type 2 inflammation and PLC pathogenesis, warranting further investigation. Dupilumab could serve as a promising therapeutic alternative for refractory PLC.

Keywords:
Biologics - Case report - Depigmentation - Dupilumab - Pityriasis Lichenoides Chronica - Pityriasis Lichenoides et Varioliformis Acuta - PLC - Vitiligo