[A Case of Noninvasive Ductal Carcinoma Arising in Benign Phyllodes Tumor].

A 70-year-old woman underwent a partial mastectomy with preoperative diagnosis of phyllodes tumor. Histopathological examination of the resected specimen revealed noninvasive ductal carcinoma of up to 20 mm in the phyllodes tumor. We note the possibility of a situation in which a phyllodes tumor is accompanied by cancer, and detailed pathological examination is necessary.