Breast metastasis from nonmammary malignant neoplasms is uncommon, and it accounts for approximately 2% of all breast tumors. Distant metastasis of thymoma is very rare, and especially to extrathorcic areas. We report a female who had a metastatic thymoma in her breast 20 years after undergoing resection for a non-invasive thymoma. She presented with a palpable mass in her left breast. Mammography and ultrasonogram showed a lobular mass at the anterior glandular portion. Histological examination after surgical excision revealed a metastatic thymoma.
Breast Neoplasms/diagnosis/*secondary/surgery ; Female ; Humans ; Magnetic Resonance Imaging ; Middle Aged ; Thymoma/diagnosis/*secondary/surgery ; Thymus Neoplasms/diagnosis/*pathology/surgery ; Tomography, X-Ray Computed ; Ultrasonography, Mammary