Primary Treatment for Cellular Fibroepithelial Neoplasm
Surgical excision is the primary treatment for cellular fibroepithelial neoplasms to definitively distinguish between fibroadenoma and phyllodes tumor, as core needle biopsy alone cannot reliably make this distinction. 1
Rationale for Surgical Excision
The fundamental challenge with cellular fibroepithelial lesions is that core needle biopsy (CNB) cannot reliably differentiate between benign fibroadenoma and phyllodes tumor, which have vastly different clinical implications. 1, 2
- Upgrade risk: When cellular fibroepithelial lesions are diagnosed on CNB and subsequently excised, approximately 60% prove to be phyllodes tumors rather than fibroadenomas. 1
- Sampling error: Core biopsy samples only a small portion of the lesion, potentially missing areas of stromal overgrowth or increased cellularity that would indicate phyllodes tumor. 3
Surgical Approach
Wide local excision with negative margins is the treatment of choice for all cellular fibroepithelial neoplasms. 4
- The goal is complete removal with clear margins to prevent local recurrence, particularly if the lesion proves to be a phyllodes tumor. 4
- Margins of at least 1 cm are typically recommended for phyllodes tumors, though this is determined at final pathology. 4
Risk Stratification for Phyllodes Tumor
Certain features on CNB increase the likelihood that a cellular fibroepithelial lesion will prove to be a phyllodes tumor: 1
- Patient age ≥40 years (independent predictor)
- Stromal overgrowth on CNB specimen (independent predictor)
- Increased stromal cellularity (independent predictor)
- Larger lesion size (particularly >3 cm on imaging) 2, 5
Alternative Management: Active Surveillance
Active surveillance may be considered only in highly select cases where all of the following criteria are met: 5
- Small lesion size (<2 cm on ultrasound) 5
- Benign imaging characteristics with complete concordance between clinical, radiologic, and pathologic findings 3, 2
- Patient preference after informed discussion of risks 5
- Ability to comply with close follow-up (ultrasound every 6 months initially) 5
However, this approach carries risk: even with careful selection, 2% of excised lesions prove to be borderline or malignant phyllodes tumors. 5
Common Pitfalls to Avoid
- Do not rely on size criteria alone for deciding on excision—98% of fibroadenomas excised solely for size >3 cm remain benign at final pathology. 3
- Do not assume benignity based on CNB showing "cellular fibroepithelial lesion"—60% upgrade to phyllodes tumor. 1
- Do not perform inadequate excision—positive margins in phyllodes tumors lead to high local recurrence rates. 4
- Do not dismiss patient age—women ≥40 years have significantly higher risk of phyllodes tumor. 1
Post-Excision Management
Final pathology determines subsequent management: 4
- Benign fibroadenoma: No further treatment required; return to routine screening
- Benign phyllodes tumor: If margins negative, surveillance only
- Borderline/malignant phyllodes tumor: Re-excision if margins positive; consider adjuvant therapy for malignant variants (though evidence is limited) 4