Thyroid Metastasis from Breast and Lung Cancer in Patients with Underlying Hashimoto’s Thyroiditis

Metastatic disease involving the thyroid gland is uncommon. Thyroid metastases has been previously described from several primary cancers of lung, breast, and kidney. Because of the lower incidence and ambiguous clinical significance, it is not easy to consider thyroid metastasis and decide the optimal time for performing diagnostic examination. Here, we reported two cases of metastatic diseases of thyroid in patients who had underlying Hashimoto’s thyroiditis: a 39-year-old woman who had thyroid metastasis of breast cancer with underlying Hashimoto’s thyroiditis, and a 44-year-old woman with metastatic lung cancer.