Introduction: Metastases to the thyroid gland are very rare. They are usually seen in malignant melanoma, kidney, breast cancer and lung cancer.
Case report: We presented a 54-years-old female patient with breast cancer diagnosed in 2002. The adequate surgical procedure was done and the tumor and axillary lymph nodes were removed. The patient also received adjuvant postoperative chemotherapy. After seven years of a disease free period, the first relapse of the disease was detected as thyroid gland tumor with axillary lymphadenopathy. The patient had a good response to systemic treatment so the surgical removal of thyroid gland and enlarged lymph nodes was performed. Histopathological analysis confirmed metastasis with breast cancer origin. Radical mastectomy was also preformed. Second relapse of the disease was detected 10 months later, while the patient was on hormonal therapy. It was manifested as the appearance of bone and skin metastases, pleural effusion and lymphadenopathy.
Conclusion: This case report emphasized the importance of detailed examination of any new onset of thyroid swelling in a patient with previous history of malignancy.