Spindle cell carcinoma of the breast - A case report.

Spindle cell carcinoma (SpCC) of the breast is quite a rare modality classified to the metaplastic carcinoma of the breast. Regarding its biological behavior and the prognosis of the patients with this rare tumor, it has been remaining controversial. We herein report an 88 year-old woman who had a huge bleeding tumor on the right breast. She was a high-aged woman with low activities of daily life, even with some suspicion of distant organ metastasis. While the tumor proved to drastically bleed due to the tumor disintegration, a right simple mastectomy was performed. According to the histopathologic examinations, sarcomatoid spindle cells with severe atypia were observed. By an immunohistochemical examination, the tumor had proved to express neither estrogen receptor, progesterone receptor nor HER2 receptor. Moreover an immunohistochemical expression of AE1/3 and CAM5.2, defining an epithelial neoplasm were observed in addition to an expression of vimentin. From these findings, this bleeding tumor was diagnosed as spindle cell carcinoma of the breast. J. Med. Invest. 67 : 365-367, August, 2020.