Thyroid Cancer Presenting with Concomitant Metastatic Breast Cancer in the Thyroid

The thyroid is an unusual site to find cancer metastasis. When it does occur, such cancer spread is often manifested in multiple metastases and generally suggests a poor prognosis. We presented here a 49-year-old woman recently diagnosed with thyroid cancer, who had been treated for stage IIA breast cancer 8 years ago. After radical right thyroidectomy and left subtotal thyroidectomy, her pathological report showed papillary thyroid carcinoma, right thyroid, with concomitant metastatic breast carcinoma. This is the first case of which we are aware involving coexisting thyroid cancer and metastatic breast cancer in the ipsilateral lobe. Moreover, the circumstances of this case show a very unique clinical course compared with previous studies. Given the unusual circumstances of our case, we further discuss the relationship between thyroid cancer and breast cancer.