[A Case of Breast Carcinoma with Cartilaginous Differentiation and Distant Metastasis with Complete Response to Post-Operative Chemotherapy].

We report a case of breast cancer with cartilaginous differentiation that responded well to chemotherapy, which completely eliminated distant metastasis. A 63-year-old woman visited our hospital complaining of a large hemorrhagic mass measuring 15 cm in diameter with ulceration of the left breast. Palpation revealed swelling of the left axillary and right supraclavicular (SC)lymph nodes, suggesting breast cancer metastasis. A CT scan revealed metastasis in the right lung measuring 2.5 cm in size. She underwent a total mastectomy with axillary dissection. The pathological findings were as follows; breast carcinoma with cartilaginous differentiation accompanied by a single lymph node metastasi(s 1/21)and skin involvement, ly0, v0, ER(-), PgR(-), HER2 0, Ki-67 80%. Four courses of AC therapy were administered as postoperative chemotherapy, which resulted in a decrease in the size of the SC lymph node to 1 cm. Subsequently, 12 courses of weekly paclitaxel yielded a complete response of the lung and SC lymph node metastasis. Oral administration of S-1 after paclitaxel therapy resulted in no recur- rence for 16 months after the operation.