Abstract
Radiation recall dermatitis (RRD) is an inflammatory reaction that occurs at previously irradiated skin regions after drug administration. We herein report a patient with non-small-cell lung cancer treated previously with thoracic radiotherapy who developed severe RRD induced by atezolizumab [anti-programmed death 1 ligand 1 (PD-L1) antibody]. Immunohistochemistry of the skin biopsy showed dermatitis with infiltration of CD8+ lymphocytes, suggesting that atezolizumab might provoke an immune-related inflammatory reaction at previously irradiated skin regions. When administering anti-PD-L1 antibody to patients who have undergone radiotherapy previously, physicians should carefully monitor the irradiated skin for the potential occurrence of RRD.