Pembrolizumab is a highly selective, humanised monoclonal anti-programmed death 1 (anti e PD-1) antibody that prevents PD-1 from engaging with PD-1 ligand, thus increasing the immunol. antitumor response.The incidence of cutaneous side-effects for anti-PD-1 ther- apy has been estimated to affect 20% e 49% of treated patients with reactions ranging from mild and non- specific rashes to life-threatening dermatoses.The patient was diagnosed with disseminated non- e small-cell lung cancer in 2017 and started pem- brolizumab therapy in July 2018, having experienced toxicity from conventional chemotherapy.The clin. and histol. presentations were consistent with a diagnosis of subacute cutaneous lupus erythematosus and the criteria for drug-induced sub- acute cutaneous lupus erythematosus as previously described were all met.The emerging use of anti e PD-1 to effectively treat various types of cancers, underpins the need for an improved understanding of potential dermatol. adverse effects, as well as the potential clin. care.