Cystosarcoma phyllodes metastatic to a brenner tumor of the ovary

A patient had cytosarcoma phyllodes that developed metastases to bone and to a Brenner tumor of the ovary. The original breast tumor was reported as benign, but the patient died of metastases four months following mastectomy. The rapid growth in the ovary may have been due to estrogenic stroma in the Brenner tumor. This is the first report, to our knowledge, of cystosarcoma phyllodes metastasizing to another tumor.