Abstract
A 75-year-old woman visited our hospital complaining of a palpable left breast mass. The tumor was 20 mm in the upper outer quadrant of the left breast and left axillary mass was 20 mm in diameter. Breast cancer with axillary lymph node metastasis was suspected by mammography and ultrasonography. Core needle biopsy indicated invasive ductal carcinoma accompanied by myxomatous extracellular matrix and multinucleated giant cells. At this point, a special type of breast cancer was suspected. This patient underwent left mastectomy and axillar lymph node dissection for breast cancer (T2N1M0, stage IIB). Histologically, the tumor consisted of poorly differentiated invasive ductal carcinoma, pleomorphic and spindled tumor cells admixed with chondroid metaplasia. These components showed positive staining for vimentin and metaplastic carcinoma was diagnosed. Additionally, tumor cells expressed estrogen and progesterone receptor-negative and HER2-negative (triple negative).
