Phyllodes Tumour

Phyllodes Tumour is also known as cystosarcoma phylloides. It is usually benign but 10-20% may be malignant.

Basic Pathology

These are special tumours of the stroma of the glandular breast as opposed to soft tissue sarcomas. They can be benign, borderline or malignant; most are benign. The tumour is characterised by proliferation of stromal tissue which form leaf like projections into a lumen lined by benign epithelium (containing epithelial and myoepithelial cells). Mitotic rate is the main distinction for malignancy; benign tumours have < 4 mitoses per 10 hpf whereas malignant tumours have > 10 per 10 hpf. They can be differentiated from benign fibroadenoma by increased cellularity in the stroma; malignant cases have a highly cellular stroma with marked pleomorphism. Margins are pushing in benign cases but infiltrative in malignant cases.


Phyllodes tumour presents in a similar method to adenocarcinomas of the breast; it often occurs in younger women and may be confused for a fibroadenoma. They are usually rounded, firm and painless. On average, tumours are about 5 cm at detection.


Surgical excision is usually curative. Axillary dissection is only indicated if nodal involvement is found clinically. There is minimal evidence supporting or refuting adjuvant radiotherapy; it is often given lesions with involved margins or when malignant disease is present and margins are < 1 cm. When margins are > 1 cm, there is minimal evidence to support radiotherapy but it is commonly given regardless. Most studies are retrospective case series.
Cytotoxic therapy has no established role except in metastatic disease, which usually occurs to the lungs. Hormonal therapy is ineffective.