Severe lichenoid eruption due to concomitant medications following nivolumab administration

Recently, immune checkpoint inhibitors have been administered for several cancers and have shown great efficacy. However, they are associated with various immune‐related adverse events. Here, we report a case with severe lichenoid eruption following nivolumab administration that improved after the withdrawal of concomitant medications and the patient could continue nivolumab therapy. While nivolumab has been reported to cause severe skin reactions, the current case suggests that severe cutaneous manifestations after nivolumab administration could also be caused by the acquisition of immunogenicity of concomitant medications, including the one that was safely administered before nivolumab treatment and discontinuation of them may enable the patient to continue nivolumab therapy.