CPC02 Delayed widespread lichenoid drug reaction with radioisotopic response in a patient treated with nivolumab

Abstract The introduction of immune checkpoint inhibitors for the treatment a wide variety malignancies has led to rise in cutaneous immune-related adverse events (irAEs), including autoimmune and autoinflammatory skin conditions, which typically present within first 16 weeks treatment—on average, 3.6 after drug initiation. Cutaneous irAEs occur approximately 8.7% patients receiving antiprogrammed cell death type 1 therapy (PD-1). Nivolumab is an antibody against PD-1 widely used various cancers. As application these therapies expands, understanding their effects essential. We 76-year-old woman with metastatic renal carcinoma, who developed widespread pruritic eruption 18 months commencing nivolumab. Examination revealed papular vesicular rash affecting arms, legs, anterior chest, face, hands feet. There was confluent well-demarcated rectangular area grouped papules on right side her back; this site had been treated radiotherapy localized rib metastases month prior onset rash. no mucosal involvement systemic symptoms. Three biopsies were taken, showed vacuolar alteration basal layer band-like inflammatory infiltrate at dermoepidermal junction, focal areas subepidermal separation. Direct immunofluorescence negative, swabs negative bacterial viral infection. A diagnosis delayed bullous lichenoid reaction secondary nivolumab made. involving previous field considered be radioisotopic response rather than radiation recall as she already when it occurred. She discontinued commenced oral prednisolone settled over 5 weeks. Lichenoid dermatitis known associated therapy, improved survival outcomes noted therapy. Typically, occurs weeks, documented range 1–266 days. This patient 550 days, concurrent site. Radiotherapy-induced lichen planus rare, only one case report documenting outside irradiated field. found reports causing such protracted period. adds growing literature around inhibitor-associated eruptions.