Slide 85.Phyllodes tumor, Breast

A. Brief Descriptions

  1. Arise from intralobular stroma; previously known as “cystosarcoma phyllodes”.

  2. Classification: benign, low-grade malignant and high-grade malignant.

  3. Changes suggesting malignant potential: increased cellularity, high mitotic rate, nuclear pleomorphism, stromal overgrowth, and infiltrative borders.

B. Gross Findings

1.   Well-circumscribed tumors with leaf-like pattern and fleshy appearance.

C. Micro Findings

  1. Leaf-like projection of stroma.

  2. Stromal hypercellularity and presence of benign glandular elements.

  3. Increased mitotic figures.

D. Others:

  1. Compare with slide 84, fibroadenoma of breast.

E. Reference

  1. Robbins Pathologic Basis of Disease, 6th ed.  P.1103-1104.



Fig. 85-1 (LP)Circumscribed  tumor with leaf-like projection.




Fig. 85-2 (LP)Leaf-like pattern.Proliferating stroma covered by benign ductal epithelium.



Fig. 85-3 (LP)Stromal hypercellularity and presence of benign ductal element (right upper).



Fig. 85-4 (HP)Increased stromal cellularity with mitotic figures.