Phyllodes tumor

Phyllodes tumor is a rare fibroepithelial breast tumor that typically manifests in individuals between 40–50 years of age as a painless, multinodular breast mass. Unlike fibroadenomas, phyllodes tumors tend to increase in size more rapidly over time. On breast ultrasound, phyllodes tumors appear as a hypoechoic solid mass containing cysts; on mammography, they appear as a hyperdense mass. Biopsy is required for diagnostic confirmation. Histological findings of stromal cellularity and leaf-like architecture distinguish phyllodes from fibroadenoma. Phyllodes tumors are categorized as benign, borderline, and malignant according to the following features: border infiltration, mitotic activity, stromal atypia, and hypercellularity. Malignant or borderline phyllodes tumors can metastasize hematogenously. Surgical excision is recommended for nonmetastatic disease. Metastatic phyllodes tumors carry a poor prognosis; management (e.g., palliative surgery, chemotherapy) should be tailored to the individual. Phyllodes tumors have a high rate of recurrence after surgical excision.

• Account for < 1% of breast lesions
• Peak incidence: 40–50 years

Epidemiological data refers to the US, unless otherwise specified.

• Painless, multinodular lump in the breast, with an average size of 4–7 cm
• Variable growth rate: may grow slowly over many years, rapidly, or have a biphasic growth pattern

Compared to phyllodes tumors, fibroadenomas tend to be smaller in size, remain the same size or grow slowly, and usually occur in younger (20–30 years) women. ^[2]

Follow age-appropriate diagnostic workup for a palpable breast mass. The findings specific to phyllodes tumor are described here.

Phyllodes tumors and fibroadenomas have similar clinical presentations and imaging features. If phyllodes tumor is suspected, a biopsy is necessary to confirm the diagnosis. ^[2]

Imaging findings

• Breast ultrasound: hypoechoic solid mass that may contain cysts ^[3][4]
• Mammography: hyperdense mass ^[2][4]

Phyllodes tumors may be indistinguishable from fibroadenomas on imaging, but features such as larger size, the presence of cysts, or a hyperdense mass on mammography should raise concern for phyllodes tumor. ^[2]

Biopsy

• Indications: all patients with suspected phyllodes tumor ^[2]
• Modalities ^[1][2][5]
  • Core needle biopsy
  • Excisional biopsy
• Findings ^[5]
  • Leaf-like architecture with papillary projections ; of epithelium-lined stroma (connective tissue) ^[6]
  • Phyllodes tumors are histologically categorized as benign, borderline, or malignant. ^[2][5]

Stromal cellularity and leaf-like architecture are key histological findings that distinguish phyllodes tumors from fibroadenomas. ^[2]

While phyllodes tumors are typically benign, some are malignant and have the potential to metastasize. Phyllodes tumors should be considered malignant until proven otherwise. ^[2][3]

Refer all patients with phyllodes tumors to a breast surgeon or surgical oncologist for management.

• Benign phyllodes tumor: surgical excision
• Borderline or malignant phyllodes tumor: Assess for metastases (e.g., CT chest).
  • Nonmetastatic disease:
    • Wide excision (1 cm margin), if feasible
    • Adjuvant radiation may be considered to minimize the risk of recurrence.
  • Metastatic disease:
    • Palliative surgery
    • Chemotherapy may be considered on an individual basis.

• High risk of recurrence after excision ^[2]
• Borderline and malignant phyllodes can metastasize hematogenously.
• Metastatic phyllodes tumor has a poor prognosis.