Breast: Phyllodes Tumor

Phyllodes Tumor

Basics

  • Definition: Fibroepithelial Breast Tumor
  • 15% Risk for Recurrence (Local or Contralateral)
  • Rare Hematogenous Spread
    • Most Common Site of Mets: Lung

Presentation

  • Smooth Multinodular Mass
  • Firm & Mobile
  • Generally Painless
  • Often Large (Average 4-7 cm) – Generally Larger than Fibroadenomas
  • Can Ulcerate
  • Many (Up to 20%) Have Palpable Axillary Lymphadenopathy Although Most are Reactive
    • Metastatic Lymph Node Involvement is Rare

Diagnosis

  • Initial Evaluation: Imaging (Mammogram/US)
    • May Also Consider MRI
  • Diagnosis: Core Needle Biopsy (CNB)
    • Pathology: Stromal Hypercellularity with Leaf-Like Projections
      • Vimentin & Actin Stain Positive
  • May Be Difficult to Distinguish from Fibroadenoma
    • Imaging for Both May Show Smooth Multinodular Mass
    • Biopsy for Both May Show Cellular Fibroepithelial Lesion
  • *See Breast: Breast Mass Evaluation

Histologic Classification

  • Classifications:
    • Indeterminate
    • Benign
    • Borderline
    • Malignant
  • Based On:
    • Degree of Stromal Cellular Atypia
    • Mitotic Activity
    • Infiltrative Margins
    • Presence of Stromal Overgrowth – The Most Consistently Associated with Aggressive/Metastatic Behavior

Treatment

  • Primary Treatment (Borderline or Malignant): Wide Local Excision (WLE)
    • Margin: ≥ 1 cm
    • Mastectomy May Be Required if Large or Comprising the Majority of Breast Volume
  • Does Not Require SLNB or XRT
  • Consider Excisional Biopsy Alone (Without Intent of Obtaining Surgical Margins) for Indeterminate or Benign Phyllodes Tumors

Phyllodes Tumor 1

References

  1. Nephron. Wikimedia Commons. (License: CC BY-SA-4.0)