Phyllodes tumors: Understanding types, risks and treatment

Updated December 7, 2023

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Phyllodes tumor in a 52-year-old woman.

By Professor Dr See Mee Hoong
Consultant Oncoplastic Breast Surgeon,
UM Specialist Centre

Phyllodes tumors, a distinctive type of tumor with unique characteristics, encompass three categories: phyllodes tumor, cystosarcoma phyllodes, and benign cystosarcoma, presenting as a serocystic disease of Brodie. These tumors exhibit leaf-like projections in pathology specimens, aiding in their diagnosis.

Originating from diverse cell types within the breast including dark cells, lobules and the surrounding supporting tissues, phyllodes tumors arise primarily in the connective stromal tissue, diverging from the usual sites of breast cancer formation. Most cases are benign, with only a fraction progressing to malignancy.

Predominantly affecting women in their 40s but potentially occurring at any age, these tumors manifest in three histological types:

Benign tumors: These account for more than half of all phyllodes tumors. They are the least likely to grow quickly or spread.
Borderline tumors: These exhibit features between benign and malignant tumors.
Malignant tumors: Accounting for about 1 in 4 phyllodes tumors, these tend to grow rapidly and are more likely to spread or recur after treatment.

Differential diagnosis involves evaluating mitotic rate, stromal cellularity, and tissue abnormalities, impacting the required surgical or therapeutic approach.

Symptomatically, phyllodes tumors present as firm, often painless breast lumps, rapidly enlarging and occasionally causing skin distension. Diagnosis typically involves imaging tests or core needle biopsies, although complete tumor removal via excisional biopsy might be necessary for conclusive identification.

While benign phyllodes tumors do not increase breast cancer risk, malignant cases might require vigilant monitoring post-treatment due to potential recurrence.

Treatment predominantly involves surgical removal, varying from excisional biopsies for benign tumors to wider resections and possible mastectomies for malignant variants, often supplemented by radiation therapy.

However, malignant phyllodes tumors pose challenges in treatment response compared to conventional breast cancers, necessitating a different therapeutic approach resembling soft tissue cancer management.

Close post-treatment monitoring, including regular breast exams and imaging, is crucial due to the propensity for local recurrence. Understanding these tumors' distinct features and their impact on breast health aids in tailoring effective management strategies for improved outcomes.