Phyllodes tumours are rare tumours of the connective tissue (stroma) of the breast, occurring most often between ages 40 and 50. They are large and fast-growing. They can be benign (~50%), borderline (~25%) or malignant (~25%). Malignant phyllodes tumours can metastasise.

Treatment involves surgical removal of the tumour and the surrounding tissue (“wide excision”). They can reoccur after removal.

Chemotherapy may be used in malignant or metastatic tumours.