Phyllodes Tumor of the Breast

Definition

Mixed epithelial and stromal/mesenchymal proliferation of breast characterized by increased stromal cellularity and characteristic broad "leaf-like" papillae inserted into cleft-like spaces

Usually large and grossly circumscribed
Fibroepithelial proliferation with broad "leaf-like" papillae inserting into slit-lilke or cleft-like spaces
- Exaggerated intracanalicular pattern
Cellular stroma
- Periductal stromal condensation may be seen
Frankly sarcomatous stroma may be seen in malignant phyllodes tumor
- Heterologous differentiation may occur in malignant phyllodes tumor
  - Liposarcoma
  - Osteosarcoma
  - Chondrosarcoma
  - Rhabdomyosarcoma
Grading determined by presence or absence of atypical stromal features

Kristin C Jensen MD
Richard L Kempson MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting:: January 10, 2007