Breast: 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