MONDO_0021047 (breast phyllodes tumor) is a benign, malignant, or borderline circumscribed biphasic neoplasm that arises from the breast. It usually affects middle-aged women. It is characterized by the presence of a double layer of epithelial cells that are arranged in clefts, surrounded by a spindle cell mesenchymal (stromal) component. Also known as: breast cystosarcoma phyllodes, breast phyllodes neoplasm, cystosarcoma phyllodes of breast, cystosarcoma phyllodes of the breast, cystosarcoma phylloides - breast, cystosarcoma phylloides of the breast, phyllodes breast neoplasm, phyllodes breast tumor.