Abstract
We have experienced a case of a giant solitary metastatic mediastinal tumor after surgery for breast cancer which required differentiation from primary thymic cancer and responded well to therapies, with resultant long-term remission. The case involved a 65-year-old woman who had undergone surgery for left breast cancer at the age of 54. She only complained of swelling of the neck. On imaging findings, a giant solitary tumor with the maximum diameter of 9.8 cm and the longer axis of 19.6 cm, extending from the neck to the middle mediastinum was identified, but no infiltration into the surroundings and lymph node metastases were seen. There was no recurrent laryngeal or phrenic nerve palsy as well as stenosis of the large vessels or esophagus. Biopsy resulted in HER-2 positive poorly differentiated epithelial tumor. At first, primary tumor of the mediastinum was suspected, but thereafter metastatic mediastinal tumor was diagnosed based on a histologic comparison with the breast cancer. Radiation therapy followed by chemotherapy with ADDC achieved a partial remission (PR), and further change to trastuzumab from ADOC resulted in complete remission (CR). CR has been maintained as of 3 years after the initiation of the therapy.
