11.4 Phyllodes Tumors & Breast Angiosarcoma

Phyllodes Tumors

What They Are

Phyllodes tumors are fibroepithelial neoplasms, like fibroadenomas, but with a hypercellular stroma that forms leaf-like (phyllodes) projections into cystic spaces. They make up less than 1% of breast tumors. Key contrasts with fibroadenoma:

Clinically, a phyllodes tumor is a smooth, mobile, painless mass that may enlarge quickly; large tumors stretch the skin, cause visible veins, or ulcerate. Imaging often looks like a fibroadenoma, and core biopsy may not distinguish them. A "fibroadenoma" that grows rapidly or is larger than about 3 cm should be excised.

Grading

The WHO classifies phyllodes tumors as benign, borderline, or malignant based on stromal cellularity, nuclear atypia, mitotic activity, stromal overgrowth, and margin appearance (pushing or infiltrative). Most are benign.

Treatment

• Wide local excision aiming for margins of about 1 cm is the standard. For benign tumors, narrower negative margins may be acceptable if re-excision would cause significant deformity. Mastectomy is needed only when negative margins cannot be achieved with acceptable cosmesis.
• No axillary staging. Lymph node metastases occur in well under 1% of cases, so sentinel node biopsy and axillary dissection are not recommended.
• Radiation may be considered after excision of malignant or borderline tumors, especially with close margins, to reduce local recurrence.
• Chemotherapy is not standard; metastatic malignant phyllodes tumors are treated like soft tissue sarcomas.
• Endocrine therapy has no role, even though the epithelial component may express hormone receptors.

Malignant phyllodes tumors spread hematogenously, most often to the lungs and bone. Local recurrence can occur even after benign tumors, so surveillance includes clinical examination and breast imaging every 6 to 12 months for several years. Very young patients or those with a family history of sarcoma may warrant consideration of Li-Fraumeni syndrome.

Breast Angiosarcoma

Two Forms

Angiosarcoma is a malignant tumor of endothelial (vascular) cells and makes up less than 1% of breast malignancies.

• Primary angiosarcoma arises in the breast parenchyma of young women (often 20s to 40s) without prior radiation and presents as a deep mass, sometimes with bluish overlying skin.
• Secondary (radiation-associated) angiosarcoma arises in the skin of the treated breast or chest wall a median of about 6 years after radiation, usually in older women treated with lumpectomy and radiation. It occurs in roughly 0.05% to 0.3% of irradiated patients, so it is rare but increasingly seen as more patients survive breast cancer.
• Stewart-Treves syndrome is angiosarcoma arising in a chronically lymphedematous arm, classically after radical mastectomy.

The Easily Missed Presentation

Secondary angiosarcoma looks like a painless bruise, purple or red discoloration, violaceous papules or nodules, or skin thickening within the radiation field. It is often mistaken for radiation changes, a hematoma, or a benign vascular lesion, and delays are common. Any new purple or bruise-like lesion on a previously irradiated breast without trauma needs a punch biopsy. Pathology shows endothelial markers (CD31, ERG), and radiation-associated tumors typically show MYC amplification.

Treatment and Prognosis

• Surgery: wide resection to negative margins, usually mastectomy with removal of all irradiated skin when feasible, sometimes requiring flap coverage. Lymph node dissection is not routine.
• Radiation: hyperfractionated re-irradiation is used in some centers to reduce local recurrence.
• Systemic therapy: taxanes (especially weekly paclitaxel) and anthracyclines are active for unresectable, recurrent, or metastatic disease.
• Prognosis: local recurrence is frequent and survival is poor compared with breast carcinoma, particularly for secondary angiosarcoma.

Nursing Priorities

• Teach survivors who had breast radiation to report any new purple, red, or bruise-like skin changes in the treated area, even many years later.
• For phyllodes tumors, explain that no lymph node surgery is needed and why surveillance continues after a "benign" diagnosis.
• Prepare patients with angiosarcoma for extensive surgery and possible reconstruction with flaps, and address the psychological weight of a second cancer caused by treatment of the first.

Imaging and Biopsy Clues

• Phyllodes tumors on ultrasound tend to be large, lobulated, and heterogeneous, sometimes with internal cystic spaces or clefts. Core biopsy that shows increased stromal cellularity, stromal overgrowth, or mitoses should prompt excision rather than surveillance. A growing "fibroadenoma" is excised even when the core biopsy looked benign.
• Angiosarcoma may look normal or show only skin thickening on mammography; MRI better defines extent. Because skin involvement can extend beyond what is visible, surgeons often remove wide areas of irradiated skin.

Comparing the Two Rare Tumors

Survivorship Teaching

Patients treated for either tumor need clear explanations of why their care differs from "usual" breast cancer: no endocrine therapy for phyllodes tumors, and no sentinel node biopsy for either. Regular clinical examinations and imaging continue because local recurrence is the main risk.