Pembrolizumab is a monoclonal antibody against programmed cell death-1 (PD-1) protein and acts as an immune checkpoint inhibitor by preventing the interaction of the PD-1 receptor with its ligands [
1]. Over the last few years, immune-related events involving the central nervous system in oncological patients have grown due to the increasing use of PD-1 inhibitors [
1]. We describe a patient with lung adenocarcinoma who developed autoimmune rhomboencephalitis shortly after treatment with Pembrolizumab with positivity of serum anti-amphiphysin autoantibodies; an atypical presentation for both immune-related adverse events (irAEs) to PD-1 inhibitor and anti-amphiphysin paraneoplastic neurological syndrome (PNS). …