PDCD1 and discoid lupus erythematosus: It is well known that amongst many other drugs, programmed cell death 1 (PD-1) or programmed cell death ligand 1 (PD-L1) checkpoint inhibitors might induce SCLE, but not DLE, and thus, the PD-1/PD-L1 pathway may play a different role in the pathogenesis of different forms of CLE [14,15,16,17].