What are Phylloides tumors in adult women?

What Are Phyllodes Tumors?

Phyllodes tumors are rare fibroepithelial breast neoplasms that account for less than 1% of all breast cancers, occurring predominantly in women in their 40s, and are classified into benign, borderline, and malignant subtypes based on stromal histologic features. 1, 2

Clinical Characteristics

• Mean age at presentation is in the 40s, which is older than fibroadenomas but younger than typical invasive breast cancers 1

• The hallmark presentation is a rapidly enlarging, usually painless breast mass that can grow quickly over weeks to months 1, 3

• These tumors are composed of a benign epithelial component and cellular spindle cell stroma forming a characteristic leaf-like architecture 4

• Most commonly occur in the upper outer quadrant of the breast with equal propensity for either breast 4

Diagnostic Challenges

• Phyllodes tumors often appear identical to fibroadenomas on ultrasound and mammography, making preoperative distinction extremely difficult 1

• In the setting of a large (>2 cm) or rapidly enlarging clinical "fibroadenoma," excisional biopsy should be performed to pathologically exclude phyllodes tumor 1

• Core needle biopsy is superior to fine-needle aspiration but can still miss the diagnosis, particularly when the characteristic leaf-like architecture is not sampled 1, 5

• Frozen section has limited value (only 41.6% accuracy) 4

Classification and Prognosis

• Classified into three histologic subtypes based on stromal features:

  • Benign: 5-year disease-free survival of 95.7% 1, 6
  • Borderline: 5-year disease-free survival of 73.7% 1, 6
  • Malignant: 5-year disease-free survival of 66.1% 1, 6

• All subtypes can recur locally (approximately 11-15% overall recurrence rate), but only borderline and malignant tumors can metastasize 3, 4, 2

• Distant metastases occur in approximately 20% of malignant phyllodes tumors, most commonly to the lungs 6, 2

Risk Factors

• Patients with Li-Fraumeni syndrome (germline p53 mutation) have increased risk 1

Biological Behavior

• These tumors are locally aggressive with inherent potential for local recurrence even after adequate surgical treatment 7

• Axillary lymph node metastases are extremely rare (<1% have positive nodes), which fundamentally distinguishes them from epithelial breast cancers 6, 4

• Despite 58% containing estrogen receptors and 75% containing progesterone receptors, hormone receptor status has no therapeutic implications 1

Key Clinical Pitfall

• The most critical error is dismissing a rapidly growing breast mass as a simple fibroadenoma without tissue diagnosis, particularly in women over age 35 1, 2