TPO and autoimmune thyroid disease: Furthermore, regarding nivolumab-induced thyroiditis without relation to conventional antithyroid antibody (ATA), the novel subtype of PD-1-related autoimmune thyroiditis without both antithyroid peroxidase antibody (anti-TPO Ab) and antithyroglobulin antibody (anti-Tg Ab) observed in this study might give us a novel clue in deciphering the mechanism underlying autoimmune thyroiditis.