Several hypotheses have been implemented for the association between GD and TC as oxidative DNA damage by inflammatory cytokines and fibroblast with autoimmune disorders that can induce malignancy [12]; however, this hypothesis is not unique for GD as it can happen with other autoimmune disorders as Hashimoto's thyroiditis but that can be relevant to our case as she has positive GD and thyroid peroxidase antibodies. The gene discussed is TPO; the disease is Hashimoto thyroiditis.