What is cystosarcoma phylloides breast lump, variant of fibroadenoma?

Big lump: A phyllodes is similar to a fibroadenoma but it can get really large. In most cases they are noncancerous (benign) but there are rare malignant types. The treatment is to have it removed. If it is really large, then a breast surgeon should work with a plastic surgeon to remove it to prevent horrible defects (dents) and keep the breasts symmetrical.

No; rare cancer: Cystosarcoma phyllodes is a cancerous variant of a tumor that is uncommon but usually benign (phyllodes tumors). They can be confused with fibroadenomas, BENIGN common tumors. Can grow to be quite large, usually painless; are best completely removed after diagnosis made. Unlike other breast cancer, don't spread to lymph nodes, but spread in blood. Chemo/radiation offered. They tend to recur.