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

摘要
背景
苔藓样糠疹（Pityriasis lichenoides, PL）包含急性痘疮样苔藓样糠疹（Pityriasis Lichenoides et Varioliformis Acuta, PLEVA）与慢性苔藓样糠疹（Pityriasis Lichenoides Chronica, PLC）两类亚型，属于一组临床与组织病理特征存在重叠的炎症性皮肤病。其常规治疗手段包括口服抗生素、光疗及免疫抑制剂。度普利尤单抗（dupilumab）作为白细胞介素4受体α（IL-4Rα）拮抗剂，已获批用于特应性皮炎的治疗，且被超适应证用于其他炎症性皮肤病，但在PL治疗中的相关文献记载十分有限。

目的
报告1例成功采用度普利尤单抗治疗PLC的病例，同时观察到该患者在既往因白癜风接受单苄醚脱色治疗后，意外出现皮肤色素复色的现象。

方法
1例40岁女性患者，有广泛性白癜风病史且曾接受单苄醚脱色治疗，因出现鳞屑性红斑斑块伴剧烈瘙痒就诊。皮肤活检证实为PLC。患者因担忧色素改变而拒绝常规治疗方案，遂予度普利尤单抗治疗：负荷剂量600 mg，后续每两周予300 mg维持给药。

结果
经度普利尤单抗治疗3个月后，PLC皮损及瘙痒症状均得到显著改善，仅残留少量红斑斑块。值得注意的是，患者自发出现皮肤复色，这与既往报道的“度普利尤单抗使用后白癜风加重”的结论截然相反。后续恢复单苄醚脱色治疗并未导致PLC或瘙痒症状加重。

结论
本病例提示度普利尤单抗或可作为PLC的有效治疗手段，同时其在既往有白癜风病史的患者中可发挥促进皮肤复色的作用，这一现象颇具研究价值。上述发现提示2型炎症与PLC的发病机制可能存在关联，有待进一步研究验证。度普利尤单抗有望成为难治性PLC的潜在治疗选择。

关键词
生物制剂（Biologics）、病例报告（Case report）、脱色治疗（Depigmentation）、度普利尤单抗（dupilumab）、慢性苔藓样糠疹（Pityriasis Lichenoides Chronica, PLC）、急性痘疮样苔藓样糠疹（Pityriasis Lichenoides et Varioliformis Acuta, PLEVA）、白癜风（Vitiligo）