Extracorporeal Photopheresis ( ECP ) for Refractory Lichenoid Disorders: A Retrospective Analysis of Efficacy and Long‐Term Outcomes

Erosive Lichen Planus (ELP) is a debilitating T‐cell mediated dermatosis often refractory to conventional therapies. While Extracorporeal Photopheresis (ECP) is established for other T‐cell diseases, long‐term data on its efficacy across the lichenoid spectrum, including non‐erosive forms, remain limited. We conducted a retrospective study at Amiens‐Picardie University Hospital including five adult patients with refractory lichen (erosive or non‐erosive) treated with ECP after January 2021. Clinical response was assessed every 3 months, and progression‐free survival (PFS) was analyzed. Five female patients were included: 3 with ELP and 2 with lichen sclerosus (LS) variants. All patients achieved an initial clinical response (1 complete, 4 partial). The median time to best response was 7.5 months (95% CI: 0.8–13). At 3 months, 40% were on ECP monotherapy. Over a median follow‐up of 47 months, only one patient progressed. At the last follow‐up, two patients remained on ECP with sustained clinical benefit. Our results confirm the excellent long‐term efficacy and safety of ECP in refractory ELP. While significant initial benefits were observed in non‐erosive scleroatrophic lichen, the durability of response warrants further investigation. ECP is an effective, well‐tolerated, and sustained therapeutic option for refractory ELP and holds promise for non‐erosive lichenoid pathologies. Larger prospective studies are needed to clarify its role as monotherapy versus combination therapy.