Giant Metastatic Breast Phyllodes Tumour with an Elusive Diagnosis: A Case Report and Literature Review.

BACKGROUND: The term phyllodes tumours, which account for less than 1% of breast neoplasms, describes a spectrum of heterogenous tumours with different clinical behaviours. Less than 30% present as metastatic disease. Complete surgical resection is the standard of care so that recurrence rates are reduced. The role of adjuvant chemotherapy or radiation therapy is controversial. Patients with metastatic disease have a median overall survival of around 30 months. CASE DESCRIPTION: The authors present the case of a 57-year-old woman with an exuberant left malignant phyllodes tumour with bilateral involvement, as well as lung and axillar metastasis. The patient underwent haemostatic radiation therapy and started palliative chemotherapy with doxorubicin, achieving partial response with significant improvement in quality of life. A posterior simple mastectomy revealed a small residual tumour. DISCUSSION: Metastatic malignant phyllodes tumours are rare, so therapeutic strategies rely on small retrospective studies and guidelines for soft tissue sarcoma. Palliative chemotherapy protocols include anthracycline-based regimens, either as monotherapy with doxorubicin or doxorubicin together with ifosfamide. With few treatment options, management of these patients must rely on a continuum of care. LEARNING POINTS: Phyllodes tumours are a rare type of breast neoplasm.The differential diagnosis of breast cancer should include phyllodes tumours.Accurate and rapid diagnosis is required. © EFIM 2021.