Phyllodes Tumor. – Histopathology.guru

Derived from Greek word Phyllos, meaning “leaf”
In 1838 Muller first described this tumor as “Cystosarcoma phyllodes”
It is fibroepithelial neoplasm composed of epithelial and stromal elements
It has a predilection to affect women in 6th decade although any age may be affected
Pathological findings:
- Gross
  - Variable size with average around 4 – 5cms
  - Rapidly growing tumors
  - Well circumscribed tumors with lobulated surface
  - Cut section shows characteristic cleft spaces with grey brown stroma in whorling pattern presenting as bulbous protrusions (leaf like)
- Microscopy
  - Cleft like spaces are lined by bilayered epithelium along with myoepithelial cells
  - Stroma is composed of spindle cells which are neoplastic in this lesion
  - Stromal proliferation produces bulbous protrusions into the ductal spaces giving it leaf like architecture

Depending on the mitotic activity in the stroma, phyllodes can be
- Benign- < 5 per 10 high power fields
- Borderline – 5 – 10 per 10 high – power fields
- Malignant – >10 per 10 high power fields
Malignant tumors can show secondary changes like necrosis, hemorrhage and heterologous/ mesenchymal elements. Majority of them show EGFR amplification

- Tumor is known for local recurrence
- `Metastasis occurs through hematogenous route in malignant tumors
Treatment – Complete local excision with wide margins is recommended for all phyllodes tumors
Phyllodes tumor differs from fibroadenoma by
- stromal cellularity
- Nuclear pleomorphism and mitotic rate
- Infiltrative margins