Multidisciplinary Management of Malignant Phyllodes Tumours of the Breast: A Case-Based Illustration and Systematic Review

Phyllodes tumours (PTs) of the breast are rare fibroepithelial neoplasms with potentially aggressive behaviour, characterised by rapid growth, a significant risk of local recurrence, and occasional metastatic spread. Optimal management remains controversial, particularly regarding surgical margins, adjuvant radiotherapy, and the relevance of molecular markers in predicting tumour behaviour. A PRISMA 2020-guided qualitative systematic review was conducted of studies published between January 2000 and December 2024 in PubMed/MEDLINE, Scopus, and Web of Science. Eligible studies included malignant PTs of the breast and addressed at least one of the following domains: molecular pathology, surgical margins and local recurrence, adjuvant radiotherapy, or predictors of recurrence and metastasis. A clinical case of malignant PT treated at our institution is presented as an illustrative study. Thirty-four studies met the inclusion criteria. Evidence suggests that margin status, stromal proliferative activity, and selected molecular markers influence recurrence risk. Several retrospective studies suggest that adjuvant radiotherapy may improve local control in selected high-risk malignant PTs, although the evidence remains heterogeneous, retrospective, and potentially affected by treatment-selection bias, and no consistent survival benefit has been demonstrated. Molecular alterations, including MED12 mutations, TERT promoter mutations, TP53 alterations, and increased Ki-67 expression, have been associated with tumour progression and aggressive behaviour. A 44-year-old woman presented with a 2.4 cm left breast mass on radiological examination. Lumpectomy revealed a malignant PT with stromal hypercellularity, nuclear atypia, and a mitotic index of 20/10 HPF with close margins. Immunohistochemistry showed positivity for CD99, Bcl-2, and CD34 with a Ki-67 proliferation index of 20%. The patient underwent wide local re-excision followed by adjuvant radiotherapy (60 Gy), and at 24-month follow-up, the patient remained disease-free. Evidence synthesis highlights the importance of complete surgical excision, multidisciplinary management, and consideration of adjuvant radiotherapy in selected malignant PTs. Emerging molecular profiling may contribute to improved biological understanding and future risk stratification of malignant PTs, although its routine clinical utility remains to be validated in prospective studies.