Cystosarcoma phyllodes is an older name for rare types of benign (non-cancerous) and malignant (cancerous) breast tumors that develop in the connective (i.e., stromal) tissue of the breast. Currently, both benign and malignant custosarcoma phyllodes are called Phyllodes (or Phylloides) tumors. Although Phyllodes tumors usually are benign, they occasionally can be malignant.
Phyllodes tumors cannot be treated with hormone therapy, and they seldom respond to either chemotherapy or radiation therapy. However, both benign and malignant Phylloides tumors are treated surgically.
Benign phyllodes tumors are treated by surgical removal of the mass and a small portion of the surrounding normal breast tissue.
Malignant phyllodes tumors are treated by either surgical removal of the tumor and a wider margin of the normal breast tissue, or mastectomy (surgical removal of the affected breast).