Breast - nonmalignant
Benign tumors / changes
Phyllodes tumor - general

Author: Hind Nassar, M.D. (see Authors page)

Revised: 10 August 2017, last major update April 2010

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Phyllodes tumor of the breast [title]

See also: Phyllodes - benignPhyllodes - borderlinePhyllodes - malignant

Cite this page: Nassar, H. Phyllodes tumor - general. PathologyOutlines.com website. http://pathologyoutlines.com/topic/breastphyllodesgeneral.html. Accessed September 20th, 2017.
Definition / general
  • Biphasic tumor resembling fibroadenoma but with hypercellular mesenchymal component organized in leaf-like pattern around benign epithelial / myoepithelial lined spaces
Terminology
  • Also called cystosarcoma phyllodes (coined by Johannes Müller but not a good term since usually benign)
  • Also spelled phylloides
  • Means "leaf" in Greek
Epidemiology
  • 1% of breast tumors
  • Average age 45 years (age 25 - 30 years in Asians, Aust N Z J Surg 1988;58:301)
  • Rare in children or men (gynecomastia is more likely)
  • More common in Hispanics, particularly if born in Latin America (Cancer 1993;71:3020)
Etiology
  • A fibroepithelial tumor, like fibroadenoma; that arises from intralobular stroma
  • Rosai considers it a stromal tumor with the capacity to induce glandular formation
Clinical features
  • Tumors in young girls / women have similar morphology and behavior as older women (Am J Surg Pathol 1998;22:64)
  • Either discrete palpable mass that rapidly enlarges or nonpalpable mass identified on screening mammogram
  • Axillary nodal enlargement is present in 17% but usually reactive and not due to metastatic disease
  • Rarely secretes insulin-like growth factor II causing hypoglycemia (Breast J 2007;13:189)
Prognostic factors
Case reports
Treatment
  • Wide local excision with a rim of uninvolved breast tissue
  • Axillary nodal dissection is not necessary
Gross description
  • Well circumscribed, firm, bulging mass; often received as a shelled out specimen
  • Cut surface is tan pink gray
  • Large lesions have whorled pattern with curved clefts resembling leaf buds
  • Variable hemorrhage or necrosis in large lesions
Microscopic (histologic) description
  • Must take sufficient sections (at least one per cm of diameter) and classify based on area of highest cellular activity and most florid architectural pattern
  • Important histologic features for classification as benign, borderline or malignant:
    1. Character of tumor normal interface
    2. Proportion of neoplastic stroma to epithelial structures
    3. Mitotic figures/10 high power fields
    4. Anaplastic cytology
  • Should report presence of tumor at margin, a major determinant of local recurrence
Cytology description
  • Epithelial cell clusters, naked nuclei, atypical cells, myxoid changes
  • Background of mitotic active stromal cells
  • Fibromyxoid stromal fragments with spindled nuclei, fibroblastic pavements (Cancer Cytopathol 2010;118:33)
Positive stains
Negative stains
Electron microscopy description
  • Features of fibroblasts - myofibroblasts
Differential diagnosis