CD274 and toxic multinodular goitre: To the best of our knowledge, only one circRNA (hsa_circ_0004872) has been described to date as being involved in MNG pathogenesis by acting as a tumor suppressor, thanks to its ability to tether and suppress the onco-miR 190a-3p and to compete with Programmed death-ligand 1 (PD-L1) mRNA for the binding of the RNA-binding protein (RBP) eukaryotic translation initiation factor 4A3 (EIF4A3), determining a significant decrease in PD-L1 protein and the consequent repression of MNG cells [17,18].