Localized bullous pemphigoid in a melanoma patient with dual exposure to PD-1 checkpoint inhibition and radiation therapy

Immunotherapy with immune checkpoint inhibitors that target the programmed cell-death receptor 1 (PD-1) is increasingly used for patients with advanced or metastatic melanoma, non–small cell lung cancer, renal cell carcinoma, Hodgkin lymphoma, and urothelial carcinoma. Cutaneous adverse events that occur during treatment with these agents include pruritus, vitiligo, lichenoid dermatitis, psoriasiform dermatitis, and, more recently, bullous pemphigoid or other autoimmune blistering disease.1-8 Interestingly, radiation therapy alone has been reported as a trigger for bullous pemphigoid (BP), most often limited to the irradiated field.